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View Full Version : Way lapping, Scraping, Gib adjustment and Lock screws



haysys
07-16-2005, 01:04 PM
Hello All,

I too have an IH mill. Got it the first part of March, lapped the ways and am using it manually until I have the coin to acquire Aaron's CNC kit. The mill is a real chunk-of-a-machine, and I like it alot.

Two points here. Lapping the ways went fine, though it is work--my bursitic shoulders complained for a week. Well, I was fortunate to attend the CNC Workshop at Cardinal Engineering where they retrofitted one of the Grizzly round-column mills. One thing I took real notice of was the out-of-the-box quality of the ways: nice looking hand scraping and smooth travel (I don't know how to guage it other than by looks and quality of travel) all with NO LAPPING. This made an impression on me.

Now, my travel is fine, but it is fine because I lapped the ways. And it's not as pretty as the scraped ways, but that's no big deal.

My second point: The gibs in the Grizzly unit were adjusted to their working position with the locking screws REMOVED. Well, the gibs in my mill REQUIRE the lock screws to be adjusted to engage the gib in order to be in the working position. If the lock screws are not engaged, the table can be slightly swiveled or rocked in the the X-Y plane with the gib adjustment screws fully screwed to the extent of the adjustment range.

The significance of this did not become apparent to me until after I returned from the workshop and was thinking about what I had observed. That is, that the locking screws are being used for a purpose not intended, and the wear is going to be concentrated on two points rather than over the full range of the gibs.

What do you folks think about this???

MikeAber
07-16-2005, 07:53 PM
David,

I think you lapped your ways a lot or you also lapped the dovetails or a combination of both. I had this same problem with my Y axis. The gibb strip is tapered, and notched. Inserting some shim stock behind the nonmovement side of the gibb strip will actually improve the fit better than original as the shimstock will be more uniform than the surface. Cut a notch in the gibb strip shim to match the gibb strip as in the picture below and see if you can get the gibb strip to go in enough to eliminate the play. My shim is 0.005" thick.

Here's a trick to make it easier - use a carbide point scribe to scribe an outline of the gibb strip on the shimstock including the notch in the strip and you can flex the stock to breakout the shim from the stock.

These aren't $15,000 machines and a little shim stock here and there doesn't hurt anything.

I also was disappointed with the condition of the ways on my machine and a few other blemishes on the table. I hope current machines are improved in this regard. Having said that, I am willing to work around those issues for the advantages of the large table, long column, inch lead screws and the hardened gearset. Another advantage is Aaron, he's honest, and willing to tell you the good and bad of things with no bull.

Let us know how things work out David.

Welcome to the world of the "Big Mill".

Mike

mxtras
07-16-2005, 08:11 PM
Bursitis sucks. I race motocross and have separated each shoulder more times than I can count - each time I have a shoulder injury, bursitis kicks in.

Sleep with a heating pad wrapped around your shoulder for three or four nights - it's the only think I have found that eliminates it and it works very well.

...and that's about all I have to contribute to this thread....

Scott

haysys
07-16-2005, 09:45 PM
MIke,

That's a good idea, and precisely how I'll move forward. I concur on all counts about the mill and Aaron.

Scott,

Heat is what I use on my shoulders as well... I've walked with a cain for years, and using your arms for legs puts stress on the wrists and shoulders they were never designed for.

Regards to all!!

ChrisJ
07-16-2005, 11:55 PM
Hi Mike and Dave,

Thanks for enlightening me on the gib adjustment. I have the same issue so far on the Z slide. Gib is all the way in. I would need to use the locking screws to tighten the gibs further.
I haven't assembled the X and Y far enough yet to know if I will have the same problem on those gibs as well.
Thanks for the tip Mike.

Regards,
Chris

MikeAber
07-17-2005, 03:27 AM
It seems that we have been taught since birth that if a little is good, then more is better. Lapping your ways is one of those exceptions, Less is better!

To everyone without experience lapping the ways:
Just take the tops off of the rough (high) spots, you do not want 100% contact. I recommend you skip the coarse grades of grit entirely and start with 320 (#77) grit. Do not worry about how the ways look - just that they are smooth in operation. The low spots hold the oil to keep the ways lubricated.

The type of media you use also has a profound effect on how fast and how long the surfaces are smoothed. Silicon Carbide does not break down into smaller pieces as you continue the smoothing process. Clover Compounds are formulated from silicon carbide and other special-purpose abrasives. Silicon Carbide compounds will make the process go faster, not necessarily better. Any Silicon Carbide abrasive left behind will continue to cut until it is removed. Aluminum Oxide compounds left behind will continue to break down slowly into smaller pieces until they no longer cut anything. Timesaver media is my favorite lapping media as it does not embed itself into the metal as Silicon Carbide and Aluminum Oxide do.

"Timesaver Lapping Compound does not contain emery, aluminum oxide, silicon-carbide or similar charging abrasives. They are unconditionally guaranteed not to imbed into any metal surface. Prepared in powder form, to be mixed with oil as used. Timesaver first acts as an abrasive, then the particles diminish to a polish, and finally to inert material. TIMESAVER can be used on any hard metal friction surfaces where accurate fits are required, such as valve seats, machine tool ways, tool room applications, etc."

This is the right stuff to lap ways with: http://www.newmantools.com/lapping/time.htm#green
TIMESAVER GREEN LABEL GRADES FOR HARD METALS
(Steel, Cast Iron, Hard Bronze and Stainless Steel)
#55 Coarse #77 Medium #111 Fine #333 Very Fine

I would not lap the dovetails unless they are noticeably rough. If you find the dovetails to be rough - a few strokes with 600 or 800 (#111) grit with the gibb strips in place should make them noticeably smoother and a gentle stoning of the gibb strips is fine. While you are at this stage with everything apart take a moment to remove those razor sharp edges with a fine mill file or india oil stone - don't get carried away with large radiuses, just break the sharp edge so it can't cut you or someone else.

This should clear up some of the confusion and common mistakes made lapping ways.

If you decide to lap your ways, you are responsible for the results. No one at CNC Zone including myself, the site owner and site provider are responsible for the results.


Mike

ESjaavik
07-17-2005, 04:20 AM
Do not worry about how the ways look - just that they are smooth in operation. The low spots hold the oil to keep the ways lubricated.

That's why I'm scraping instead of lapping them. The small pockets you get when scraping are acts as oil reservoirs.

MikeAber
07-17-2005, 05:05 AM
Hi Einar,

If you have the skills to scrape the ways your method is superior to lapping and the prefered method.

haysys
07-17-2005, 03:55 PM
... While you are at this stage with everything apart take a moment to remove those razor sharp edges with a fine mill file or india oil stone - don't get carried away with large radiuses, just break the sharp edge so it can't cut you or someone else.

This should clear up some of the confusion and common mistakes made lapping ways.

If you decide to lap your ways, you are responsible for the results. No one at CNC Zone including myself, the site owner and site provider are responsible for the results.

Mike


Mike, thanks for the input. While I followed Aaron's instructions quite closely, it is certainly possible that I over-did the lapping, though I truly doubt that I removed enough material to cause the current condition. Rather I suspect the Asian folks responsible for that particular function missed the target. But who knows for sure?? Not me.

I would add one further comment on the "sharp corners" point. It is important to leave the sharp corners on the ends of the sliding way edge untouched. Reason being is to have that sharp corner plough all chips from the way surface. A less-than-sharp corner can allow small chips to be "ridden over" and cause binding and/or wear.

MikeAber
07-18-2005, 04:31 PM
Hi Don,

I exercised great caution lapping the ways on my machine and I am sure you did as well. The fact that so many have lapped the ways indicates that there is room for improvement in this area. I would have gladly paid an extra $100.00 to have an acceptable set of ways in the crate when I opened it. My $1,000.00 Harbor Freight gearhead mill didn't have this problem.

You are right, it is important to leave the sharp corners on the ends of the sliding way edge untouched.

Mike

wizard
07-21-2005, 02:49 AM
Twenty five years ago when I was throughly involved in machine tool rebuilds scrapping was considered the only valid way to fit a machine together. Though I see mention of lapping ways all over the internet, it is not something I care to suggest. The reality is the more you do it the more the surface deviates from an ideal plane.

The only time a stone gets near a set of ways being reworked is right after a scrapping session. That is only to remove burrs or high spots.

So I'm with ES take the time to scrap the surfaces in correctly if needed.

Thanks
dave




That's why I'm scraping instead of lapping them. The small pockets you get when scraping are acts as oil reservoirs.

MikeAber
07-21-2005, 03:43 AM
Wizzard,

Unfortunately, some of these Chinese mills don't have an Ideal plane on them (like mine) and most of us (hobbyists) don't have the skills to correct the situation with the prefered method (scrapeing). If I had the money for a Bridgeport or other fine machine in the same class I would agree with you 1000%.
It's difficult for some to rationalize the difference between a $15,000 commercial machine and a $1,700 Hobby Machine. The hobby machine is as huge a compromise in quality, fit and finish as lapping the ways is a compromise to scrapeing the ways.

You and ESjaavik are both right. Would you come and fix my ways for me the correct way? Please! :rolleyes:

Mike

JRouche
07-28-2005, 10:58 PM
I have an Enco version of this mill. I am converting the mill to CNC via IH goodies. I lapped the ways slightly, mostly just to clean it up slightly.

As for the tapered gib strips. I had the problem of not being able to tighten them down enough to take up excess movement. After examining the adjusting screw with the gib out I determined the screw was too long. It was bottoming in the threaded hole before bottoming at the head. I shortened the screw enough to be able to bottom out the head and still able to grab the slot on the gib while installing it. I did this on Z and X axis and can now lock the travel up if I wanted too.

On a side note. The two locking screws are not for applying gib friction or tension. They are to be used as axis locking screws as on a Bridgeport. For example: while milling along the X axis only lock the Y axis.

JRouche

MikeAber
07-29-2005, 01:52 AM
I cut another notch in my gib strip so it would go in further.

I discussed this subject with Aaron this week and his method is to push the gib strip all the way in without the screw until you lock up the axis, then mark the strip with a pencil or sharpie then pull the strip back out to the place where the screw engages the threads three or four turns and make another mark on the gib strip. Pull the gib strip out and measure the thickness with a mic at the two marks - the difference between the two is the thickness of the shim you need. By using a shim you will have a full range of adjustment to compensate for wear in the future. So far, I like the gib strip shim method best.

Mike

Mcgyver
08-02-2005, 11:14 PM
Please please please don't let lapping compound near any way/dovetail/etc or any other bearing surface - doing so makes as much sense as pouring the compound into you crankcase - there's little difference; you are voluntarily putting grit into a bearing that will wear metal away in an uncontrolled manner. Sorry if that’s harsh, but it would a real shame someone reading this thinking that lapping the ways was ok to do.

MikeAber seemed carefull to point out it was used sparingly and with fine grit, but regardless, as others have mentioned, lapping is not a substitute for scraping. if there is something wrong with the ways, you've got to identify exactly what is wrong and correct that. something not straight, not parallel, not flat etc. This is done by scraping as scraping is very localized - material is removed from exactly where you want to remove it from to solve the problem whereas lapping is wholesale material removal from everywhere. Scraping is not hard to learn (hard on the arms though).

lapping two parts together will not produce either flat, aligned or parallel parts. In a machine, all it will do is produce slop. If its a poor finish or burrs you are concerned about, break off a 3 inch piece of a worn, very fine file and skim over the surface with this. If the ways just aren’t as true as you’d like, you can ether live with it, hire it out or learn to scrape – lapping will only add to the problem. It may seem like it moves more smoothly, but only because you’ve increased the clearance (slop) between the mating surfaces; you have not made said surfaces flatter, straighter, etc. Ideally what you want is a very small clearance because the surfaces are perfectly flat and parallel, you fine tune or restore that alignment by scraping

If you have tried to lap, first thing you need to do is get all the compound out if it’s not already. this means complete disassembly and several washes/scrubs with kerosene. If you have possibly gone too far, to tell if you’ve damage it, you need a reference flat. Unfortunately they aren’t cheap but you could make one by scraping a piece of cast iron using a surface plate. any metal will do, but cast iron is less likely to move over time. using a surface plate. and you'll need it anyway if you're going to scrape :D

wizard
08-04-2005, 01:14 AM
Wizzard,

Unfortunately, some of these Chinese mills don't have an Ideal plane on them (like mine) and most of us (hobbyists) don't have the skills to correct the situation with the prefered method (scrapeing). If I had the money for a Bridgeport or other fine machine in the same class I would agree with you 1000%.

My issue is that you run a very real risk of making your machine worst, much worst in fact. It really doesn't matter if the mill is a Bridgeport or a chinese mill the problem is the same. Also even though it is described as a hobbiest machine thses small mills have a great potential when operated within their desgin limits. The key here is to keep the machine in good shape or even improve it a bit.


It's difficult for some to rationalize the difference between a $15,000 commercial machine and a $1,700 Hobby Machine. The hobby machine is as huge a compromise in quality, fit and finish as lapping the ways is a compromise to scrapeing the ways.

I disagree here, anybody that has been around machine tools can see the differrences between a hobby machine and a commercial machine. Do realize though that the machines in this forum often straddle the line between the two uses.

The hobby machine is certainly limited in many respects but the reality is that lapping ways is not an improvement at all. The point is if you want it to work better, it has the potential. That requires a bit of fine tuning, the only way to achive that at the hobbiest price point is to scrape the ways.



You and ESjaavik are both right. Would you come and fix my ways for me the correct way? Please! :rolleyes:

Mike

Mike you can do the job yourself with an old file and a flat surface and a beveled straight edge. Surface plates are pretty cheap now a days and is likely to be something that you will appreciate in the future. There are a couple books that describe how.

Thanks
Dave

MikeAber
08-04-2005, 04:52 AM
This is an endless debate and you guys are still right!

To have this job done by a professional could cost more than the machine. I own several scrapers, a surface plate, Prussian blue, and a book on the subject and I'm still not comfortable with my skills. If I had a skilled craftsman here to confirm my skills and provide guidance I probably would have gone the other way.

There's a big difference between reading something in a book and doing it correctly, or even understanding why it is or is not correct. It may be that you have years and years of experience and training to guide your hands. I have no experience or training to guide my hand. I'm a computer and electronics guy, I could tell you that installing DNS or DHCP Servers for 4,000 clients is easy and Active Directory is a piece of cake. There are books on those subjects. You may not be that confident without classroom or personalized training.

I have no experience at how to determine if the ways are true, twisted, offset, upset, mad or lying. I do know they were very rough in comparison to the ways on my other mill and lathe. I swept the table with a DTI and determined that the before and after readings are within a couple of tenths and the table is just as lousy after the job as it was before the lap job. The table runs flat within +/- .0005" in 20" on the X axis with a .005" rise on the left side in the last 5" and a .007" rise on the right side in the last 5" of travel due to the weight of the table hanging out there. The Y axis is +/- .0005" in 10" with .001 from the front to the back of the table, the same as before. Movement is smooth and predictable, my gibbs are run tight, the power feed isn't complaining any more and I'm not complaining either.

I agree with your position; however I also feel there is room for another solution if done in moderation. If I could do this all over again, I would do so, just a little less than before. If I had the skills and confidence in those skills, I would scrape the ways. Will I lap the ways on my other mill or lathe? Absolutely not! They aren't broken. Am I going to continue to discuss this issue? - I don't think so - foolish; or not, it's already been done.

I appreciate your comments and advice. I believe everyone has learned from this discussion. You are still right; scraping is the preferred method if you have the skills, I don't.

ty1295
08-04-2005, 08:31 AM
Where did you find the book and tools to scrape ways?

I have seen people do it, and have an older lathe I would like to see how much damage (well hopefully improve it) I can do.

Anybody got any good tips, websites, videos, ?? on scrapping ways? It seems like a quickly dieing art.

Mcgyver
08-04-2005, 11:13 AM
For everything you ever wanted to know about machine tool reconditioning, this is the tome
http://www.powells.com/cgi-bin/biblio?inkey=4-1114266612-0

One day I’ll buy, haven’t bothered yet.

Scrapping is a bit of a funny thing in that the way many react to it it’s like a black art or that several generations of English metal workers were of uncommonly high intelligence (well that may be). The reality is you could compare it to tapping; kind of neat and no big deal once you’ve done it. Just like tapping there are fancy things you can acquire and sometimes its challenge (like 1mm into stainless), but like tapping, for the average application its not beyond anyone’s ability – heck I’m a week warrior and have successful used scraping many times.

Here are the basics. You need a flat reference (surface plate will do), a work piece (piece of AL or cast iron if you have it) a scraper (made from old file, see fig 2254 2252 attached) and Prussian blue (old paint that doesn’t dry, available form msc etc).

Get a section of your work somewhat flat by filing/milling, whatever. Smear a thin coat of blue onto the reference. Rub the work on the reference. Pick it up and look where you rubbed it - notice the blue marks in the piece. Place the work in a vice and use the scraper, held sort of like a large wood chisel using two hands (see attachment), repeat repeat and repeat until the entire surface picks up the blue, or until your wrist falls off. You can get fancy, for example certain wrist movements can produce the gull wing shape, but it doesn’t do anything and sprung the boredom and tedium of someone scraping for months on end.

You now know how to scrape. It’s a valuable shop technique and is not just for machine tool reconditioning. Tooling can be scraped (i.e. angle plates, etc) to perfection and you can develop a surface on a casting or part so that clamping to a table for other operations won’t distort it (even a surface grinders magnetic chuck will distort things) etc. You can scrape round shapes as well so now all your plain bearings will be smooth as silk.

Btw the attachment was taken from Modern Machine Shop Practice, New York: C. Scribner's Sons, 1887-88. you can DL it at http://digital.lib.msu.edu/collections/index.cfm?AuthorID=138
Beautiful illustrations, and although 120 years old, a lot of good content.

I’ll try to take some pictures of some scrapers tonight and post them if there is interest. Sorry to be verbose, just want to encourage those interested to give it a try, its not that hard and is a valuable technique in the shop

MikeAber
08-04-2005, 01:30 PM
Finally; Someone willing to help the situation.

Thanks for taking the time to get envolved Mcgyver!

Please continue to give us guidance and enlightenment.

My Book: http://www.lindsaybks.com/bks9/hscrape/

Mcgyver
08-04-2005, 02:20 PM
like most here, glad to help....just remember the difference between an expert and lay person is only 5% but what knowledge I have i'll gladely contribute

hey just checked out your link - the illustrations are right out of the attachment I posted! I guess once its past copyright everyone's on board. 1888 content all over the cnc board

MikeAber
08-04-2005, 02:36 PM
Thanks again Mcgyver,

I ordered the Connelly book this morning.

DieGuy
08-04-2005, 03:11 PM
I have done some scraping and it isn't that tough. You know if you are going to lap then you want a straight lap, well just use that plain surface as you guide. The most difficult thing to scrape is 2 surfaces in releationship to each other and the Rubbing tool for the prussian blue is the key.

ps, we used to play tricks with the prussian blue, just put a dab on the bottom of the tool box pull of you buddy and see what happens. :D

mxtras
08-04-2005, 03:35 PM
I would suggest grinding a very subtle radius on the entire end of your scraper - this will create a more predictable and controllable tool. It will also keep the corners from digging. This creates smaller pockets depending on the radius. On a 1" wide scraper you would want the center 'high' and the ends maybe .030" 'low' - this is about a 5" radius I would guess and is typical of my favorite hand scraper.

Scraping is really easy. BUT you can screw up the initial alignment if you are not careful. If you blue up a surface against a master and it only picks up on two distinct points then you are likely getting ready to screw something up, but minimal harm can be done beacuse it is likely already giving poor results....unless you lapped it in that way in which case both of your surfaces are no longer flat. Get one surface flat, then match scrape the mating part paying attention to maintaining parallelism, flatness and squareness where necessary.

Scraping is the easy part - just relax - think of it as manual, precision machining. It's very manual...:)

Alignment, however can be a nightmare if it gets too far away, so take a good look at the alignment of the parts before you begin - you can likely make some pretty decent corrections if you can envision what needs to happen. Mark up the parts with a Sharpie before hand to show motion inflicted trends, out of squareness etc - this will help you make decisions early in the scraping process.

I don't really have the time to go into the alignment issues and techiniques but if there are specific questions, fire away - I will try. I can't say I am familiar with your individual machines, though.

Sorry to be so short - I am at work, just killing a few minutes. I felt compelled to chime in as I worked at an Austrian machine tool builder for 15 years and have substantial scraping/fitting/aligning experience on large milling and forging machines.

Scott

MikeAber
08-04-2005, 04:37 PM
This is great feedback! :cheers:

This is the kind of information you can't get in any book. You guys are great! Please continue with the tips and tricks!

I gave up before as I kept digging the corner of the scraper into the work causing more problems than I was correcting. The tip about the slight radius makes sense.

I am not comfortable at all with working on the ways of my machine until I gain some proficiency at this. Although I don't have any alignment problems I am aware of with my machines, I ordered the Connelly book today to gain some perspective on alignment issues.

Would a 90 degree angle reference plate be a good project to get started with this? I have a few cheap cast iron angle plates and would like to have a precision angle plate to use with my surface plate. Maybe a simple cast iron flat plate is the place to start and then the precision angle plate.

Mcgyver
08-04-2005, 08:03 PM
Mike, you are a serious dude. just by ordering the Connelly book you will no doubt wear the hat of board expert! As promised, i snapped pictures tonight – I hope this isn’t too much stuff.

I should emphasize that scraping and machine tool reconditioning are somewhat separate subjects, but you do need scraping to recondition. Scraping gets one surface to match a reference, presumably flat. Doing thing things like truing up an angle plate definitely uses scraping – it will get the two planes flat but to get them at 90 degrees takes a bit more to do so at exactly 90 degrees.

To do this you need either 1) an accurate master (really good toolmakers block, good angle plate etc) and a surface plate. That’s the easy route. If you don’t have a good master, you have to generate the 90 degree reference and for that you need to work in threes, angle plates A, B, C. same for creating a reference flat. There’s a process you go through, but I’d have to look it up – it’s a lot like monks flogging themselves!

Anyway, my point is that you can take the basic skill of scraping and get fancy with it using generation techniques, master squares, indicators, etc etc. but to start, just worry about, and acquire the very basic stuff to get a surface flat (my earlier post)

Here’s some basic hand scrapers – two bearing and two straight. My favorite straight is the one made from an old file, its just the nicest to use. Teeth were ground off and a fan-tail forged on the end

http://i20.photobucket.com/albums/b201/michael0100/scraping/handscrapers.jpg

Here’s a close of up the two – you can see the radii on the end as pointed out by mxtras.

http://i20.photobucket.com/albums/b201/michael0100/scraping/straightscrapercloseup1.jpg

Here’s another close up show the end – it’s not a knife edge, but square. The scraping is done with what on a lathe we’d call negative rake

http://i20.photobucket.com/albums/b201/michael0100/scraping/straightscrapercloseup.jpg

Here’s one I found on the web – nice job from an old file, no forging – that’s the cheapest/easiest way to get at it
http://easyweb.easynet.co.uk/~chrish/scrape1.jpg

Since you have to sharpen then frequently (whenever your arm needs a rest), here’s how you sharpen – mostly on the end, but clean up burrs on the side (no, I’m not using an expense water stone dry, it’s a mock up )

http://i20.photobucket.com/albums/b201/michael0100/scraping/flatsharpening2.jpg

http://i20.photobucket.com/albums/b201/michael0100/scraping/flatsharpening.jpg

Here’s an example of scraped tooling. Its an adjustable angle plate, probably could of surface ground it (I did that on the other side) but this was early on and I want to see what I could do with scraping

http://i20.photobucket.com/albums/b201/michael0100/scraping/scrapedadjustableangleplate.jpg

Here’s the ways on my full size mill, they were badly scored and had a noticeable wear in the middle. Fortunately the Dovetails were ok…it’s the flat that takes all the weight. I scraped both sides. Did one side first. then with an indicator on a scribing block base got the second one scraped into the exact same plane as the first one.

http://i20.photobucket.com/albums/b201/michael0100/scraping/scrapedmillways.jpg

Here is a beautiful set of homemade dovetail references. They were made by a friend of mine and the 24 inch monsters had been sitting around for years. When I first got them home, I blued one up and checked them – perfect – these blue out completely (a tenth or so) over their entire length on all surfaces! Amazing workmanship and testimony to the value of using the right material (cast iron). You don’t need stuff like this to do great work, for the most part they sit under my bench, just included them as part of the scraping photo essay!

http://i20.photobucket.com/albums/b201/michael0100/scraping/homemadereferences.jpg

Here’s another gem I picked up – a Brown & Sharpe camel back. Again not something that you have to have, but in interesting part of scraping lore. Here’s where you can get a casting for $200 (their’s is set up for dovetails) or the finished thing for $1,250 :O they have some books and videos as well. http://easyweb.easynet.co.uk/~chrish/scrape1.jpg

http://i20.photobucket.com/albums/b201/michael0100/scraping/BScamelback.jpg

Now I’m just going to be plain mean, when you arm is about to fall off you’ll hate me for showing you this :D

http://i20.photobucket.com/albums/b201/michael0100/scraping/powerscraper.jpg

DieGuy
08-04-2005, 08:35 PM
Ah the power scraper, Nice if you have to move lots of material, but you still need to "touch it up" by hand!

Now here is something for a first project
http://cgi.ebay.com/3-x-2-CAST-IRON-SURFACE-PLATE_W0QQitemZ7534893272QQcategoryZ58247QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

MikeAber
08-05-2005, 01:51 AM
Well, I'm very impressed with you guys, and grateful.

It seems to me that if you're going to take some of your time to educate me on this subject I would be a fool not to spend some of my time to learn a skill that I value. I knew about the book, I have read books and articles with reference to it before this and dismissed it as too expensive until now.

Mcgyver, the pictures are great, thank you for the 40,000,000 words, not too long at all.
I recognize the camel back as a reference flat. I have heard about it but this is the first time I have seen the mill file turned into a scraper. Nothing like pictures to clarify a description and an acurate description of the process.
I can relate to the tapping analogy. Before I made my mini gantry mill my tapping skills were mediocre at best and 200+ threaded holes later it is no big deal, not an expert mind you, but competent and no longer intimidated by threads in AL, CRS or HRS. SS is another story, it can be mean stuff sometimes.

DieGuy, you still have too much time on your hands! Talk about the never ending project! Shipping on that 500+ pound surface plate would be obscene.

Mxtras, your description of how to make the scraper more controllable was great and your cautionary notes are appreciated. Your experience with machine tool repair is evident and may be called upon in the future. Thanks, Scott!

Many thanks to everyone supporting this thread; your efforts here will serve hundreds more like myself who care to learn. (group)

Everyone, please feel free to continue posting questions, tips, tricks and information on on the subject of scraping in this thread!

You meet the best people here on the CNC ZONE!

IndHobby
08-05-2005, 01:51 AM
It’s funny, when I started my web site awhile back I figured people would read it, comment occasionally, blah, blah, blah…

Seem I’ve started some hotly debated topic. Lap or Scrape. That is the question.

First of all let me tell you how I thought this up.

I needed a way to improve the ways on the machines I was CNC’ing and it had to be reproducible by customers. A few years before I had hand ground an 8” telescope mirror by hand, so I figured the “average guy” can lap a mill. On the other hand I think the “average guy” will have a hard time scraping a mill. So I chose to the lesser of two evils and did a write up. That simple.

If you are up to the task so scraping, go for it. If you have never scraped a machine before and are looking to do this for the first time, God be with you. I’m not saying that I will not be with you in spirit, but insofar as being able to offer scraping advice…Well, God be with you.

Insofar as accuracy. You can get accurate results both ways if you take your time. Rushing gets you nowhere. If you wanted to lap then put some oil groves it, go for it.

If you want to get really trick, lap it, put down a negative pattern on the ways, then use ferric chloride (radio shack) and ETCH a pattern into the ways. That would be REALLY cool. (I’m not being sarcastic, it will work, and it will be cool).

Now, if you decide to lap your mill some diehard machine builders will sometime give you a little ribbing, so here is a little ribbing to give back.

Lapping (done properly) is MORE accurate.

A scraped surface is accurate to a few tenths. (0.0001) or so.

A lapped surface is accurate to MILLIONTHS. (0.000001).

Let’s look at some other surfaces that are lapped

Good telescope mirrors and lenses are hand lapped, including the Hubble.
Granite surface plates are hand lapped to a true flat state.
The flats we use to measure if a surface is flat, are usually hand lapped.

What about the trapping oil part?
It is true that scraping creates many small pockets to hold oil, but….

Similar results can be had by cutting a big Z on the smaller way and putting an oil cup to feed it. A thin layer of oil will be deposited.

Lets get even scarier than that and say that the because of the reduced viscosity of the lubri-coolant used today and the reduced surface tension of these coolants it may be BETTER to lap the ways because a micro thin layer lubri-coolant works better than a thick layer.

With all honesty, I’m just stirring the pot. If you choose to lap or scrape is fine with me. And to see people continue to scrape is an HONOR to a time tested way to build machines and the MEN who built them. It is a sign of RESPECT and CRAFTSMANSHIP that you should be PROUD of.

And if you don’t want to spend 5 years learning to scrape…I got grit.

To those who have contributed to this thread, excellent, absolutely excellent.

BTW. The pictures are first rate.

Mcgyver
08-05-2005, 09:09 AM
Aaron, if this makes an otherwise useless machine nice to use that's great. I just wanted to dispel the myth that its that hard to scrape - its not. its also not a question of lap vs. scrape, I do both, but they are not interchangeable.

The points you make about lapping are absolutely true – but not applicable. Lapping is done using a lap and the condition, treatment and monitoring of the lap is critical. Its not really fair to compare lapping using a lap to applying lapping compound between to bearing surfaces - there is no lap so there is no control point, it's just compound being used to create slop.

I have done and do flat and cylindrical lapping both using homemade and commercial laps. To get the performance you talking about with lapping requires imo a great deal of skill (would take at least 6 years to acquire).

if it works in this situation for you and your customers, peace. Given the resources at hand it may be the most expeditious way to make it usable. Then again I don't see it as a debate, it’s just not the right technique, not because I say so or tradition, but because you have no control of where material is removed. as I said its just creating slop, which might be the a practical way out of the bind but isn't really the best solution and the best solution (involves scraping) isn't as hard as many make it out to be – didn’t’ take you five years to learn how to tap did it ? :)

MikeAber
08-05-2005, 01:56 PM
Now I understand the difference between the methods under discussion here. Mxtras’s short description of alignment issues and Mcgyver’s description of control in the lapping process finally lit the light bulb for me. I can now visualize in my mind (pea brain) the methodology.

I understand Aaron’s point of view as well, he was right to develop a workaround that an “average guy” like me (hobbyist) could do to improve the ways. Not that it’s the right or wrong way to do it, but the most expedient.

As I see it now, anyone messing with the ways that doesn’t understand the methodology has the potential to cause more harm than good with any method.

wizard
08-05-2005, 04:33 PM
It’s funny, when I started my web site awhile back I figured people would read it, comment occasionally, blah, blah, blah…

Seem I’ve started some hotly debated topic. Lap or Scrape. That is the question.

It is not really a question in my mind. Lapping has its uses but certainly is not a starting point for repairs to a machines bearing surfaces.



First of all let me tell you how I thought this up.

I needed a way to improve the ways on the machines I was CNC’ing and it had to be reproducible by customers. A few years before I had hand ground an 8” telescope mirror by hand, so I figured the “average guy” can lap a mill. On the other hand I think the “average guy” will have a hard time scraping a mill. So I chose to the lesser of two evils and did a write up. That simple.

there are a couple of things that are worth noting here. first is that when you grind and lap an optical surface you have ways to check your progress through out the process. Admittedly some of the tools to check you progress are fairly simple but the fact remains you can measure the results of your lapping to within a few tenths of a wavelength.

As to scraping I would have to say that is is an easier task than mirror grinding to learn.



If you are up to the task so scraping, go for it. If you have never scraped a machine before and are looking to do this for the first time, God be with you. I’m not saying that I will not be with you in spirit, but insofar as being able to offer scraping advice…Well, God be with you.

Insofar as accuracy. You can get accurate results both ways if you take your time. Rushing gets you nowhere. If you wanted to lap then put some oil groves it, go for it.

The whole problem with lapping in a home / small shop environment is how do you check your resuts? With scrapping you can at least check your worki agianst the reference surface. Sure there are some optical methods to check a surface for flatness but that means nothing really if you don't have the equipment.



If you want to get really trick, lap it, put down a negative pattern on the ways, then use ferric chloride (radio shack) and ETCH a pattern into the ways. That would be REALLY cool. (I’m not being sarcastic, it will work, and it will be cool).

Now, if you decide to lap your mill some diehard machine builders will sometime give you a little ribbing, so here is a little ribbing to give back.

Lapping (done properly) is MORE accurate.

A scraped surface is accurate to a few tenths. (0.0001) or so.

A lapped surface is accurate to MILLIONTHS. (0.000001).

ahh but you don't want to be that accurate on a castiron to castiron bearing. A perfect match up would lead to stiction at the least an a wrung joint at the worst. It is very possible to end up with a fit that is to good. Scrapping is a valid way to achieve a surface finish that works well without resorting to rebuiliding the bearings with exotic materials. A well married saddle sould be able to sit on a castiron set of ways with little play over the entire length of travel.

In any event I fail to see how one could possibly do an accurate job of lapping ways without some sort of reference. If you are going to blue agianst a surface plate you might as well scrape.



Let’s look at some other surfaces that are lapped

Good telescope mirrors and lenses are hand lapped, including the Hubble.

yep and the often go beyone lapping to polishing. The thing is that they have the metrology equipment in place to check the figure of the mirror and to guide localized polsihing. Actually in the case of the Hubble they didn't have their metrology systems squared away, thus the mission to fix the mirror.

The question remains is what sort of optical system can one implement to do lapping on a set of ways that lets say 3 fet long to keep them flat and coplanar? I know it can be done, but not in the context we are talking about here. Now if we where to turn the discusion to methods of doing so then lapping might have a chance. I would suggest though that hand scrapping is far easier to do.



Granite surface plates are hand lapped to a true flat state.

Yes they are in some cases, though shop plates are often scraped. However the technician will map the surface plate first, optically in most cases, and rationally remove the high spots. For the home / small shop the only way to check for flatness is against a known surface such as a surface plate.


The flats we use to measure if a surface is flat, are usually hand lapped.

I'm not to sure about that nowadays but given the posibility that they still are does it matter? An optical flat is expensive plus there is the accessories that go with it. further you are not likely to find one that would be usefull on 3 feet of ways.

Even if you did you don't want the ways so flat and so perectly matted up that they won't work. For all practical purposes it isn't even worth discussing optical flatness with repsect to machine tools that the majority of us are using.



What about the trapping oil part?
It is true that scraping creates many small pockets to hold oil, but….

Similar results can be had by cutting a big Z on the smaller way and putting an oil cup to feed it. A thin layer of oil will be deposited.

The big Z is there on hand scrapped ways also. That is just there to spread oil from the distribution system. That won't be a big help on a laped surface though. Even ground ways are known to have issues with stiction and lubrication issues. Thus one often finds ground ways matted to scraped surfaces or synthetics.



Lets get even scarier than that and say that the because of the reduced viscosity of the lubri-coolant used today and the reduced surface tension of these coolants it may be BETTER to lap the ways because a micro thin layer lubri-coolant works better than a thick layer.

I would hope that lubricaiton of the ways and coolants / cutting lubs would be seen as two different things.



With all honesty, I’m just stirring the pot. If you choose to lap or scrape is fine with me. And to see people continue to scrape is an HONOR to a time tested way to build machines and the MEN who built them. It is a sign of RESPECT and CRAFTSMANSHIP that you should be PROUD of.

And if you don’t want to spend 5 years learning to scrape…I got grit.

To those who have contributed to this thread, excellent, absolutely excellent.

BTW. The pictures are first rate.
I'm not sure what to say with respect to crafftsmanship, it isn't a matter of honoring anybody. Rather I see it as the only practical approach at the price point we are talking about.

dave

ty1295
08-05-2005, 05:43 PM
Very good pros/cons for lapping.

From a practical side here is an application for the scraping guru's.

My cross slide on my lathe is 40+yrs old. If I tighten the gibs for smooth operation in center, at the ends it gets stiff. IF I adjust at ends, center is loose. Obviously from years of use, in the center position.

Now where do you start, on the flat section on one side, reference that side to the other hoping to keep it perp. to the bed way?

What if the dovetails need work?

I will be honest I thought about putting lapping compound on the machine and slide it past the high spots. Mainly I couldn't find info on scraping until now.

Mcgyver
08-05-2005, 09:54 PM
ty, what you are proposing isn't really lapping as i know it - because the accuracy (partially) in lapping comes from design,condition, shape etc of the lap! in the case you would NOT be using a lap, just two parts of the machine.....as to how to scrape it....

Oh man this is going to take awhile, but I suppose I can’t tell everyone scrape scrape scrape without being prepared to follow through. With the hedge that I know a just a little more than you and don't want to sound like an authority, I’ll give it a shot.

Scraping lets you get one surface flat as per above descriptions. The puzzle is once you get one surface flat, what tricks can one deploy to get the others flat and in their correct relative positions - no unlike constraining things with a cad program

The first thing you need is a reference (there’s a photo I took of mine in an earlier post), this needs to be this profile to fit in the dovetail. You could easily spend over a thousand but why not make it? It will teach you to scrape before you going at the machine. Get a piece of ductile cast iron (Ringball in missassauga or http://www.aia-versabar.com/ ), maybe 1.5 x2” x however long your dovetail is. Mill to a profile like:

/---------!
/ !
/_________!

Doing some googling I was reminded it’s a good idea to age it (credit to Forrest), cycle between the oven at 500 overnight then the freezer for a few days a couple of times. This works out the stresses and makes it more stable – you’ll be putting a lot into this piece so it’s worth it – it will be a precision instrument as good as anything Starrett puts out

The acute angle above is less than 60 degrees. You can’t count on the machine being at 60, and if it’s a little less it won’t fit. NOTE: you only need 1 surface on this reference! The dovetail is NOT scraped in by referencing to two surfaces at once (more on that later). It would be very difficult to scrape a perfect angle on this reference relative to each other – so from the above ASCII diagram, plan on scraping the _____ surface or the / surface. Oh, yeah, make sure the profile is wide enough to cover the widest surface you need to scrape.

Make your reference by milling the profile then scrape using the surface plate as a reference (get a cheapo composite, they’re only $100).

Now you’re ready to get started. First is a thorough inspection with the reference and blue. Actually I'd start with the Connelly book (although I don’t have it, everyone who does rave about it) because what I know only scratches the surface (pun intended). Spend a lot time figuring out what’s wrong and how to fix it. This is extremely sequential work so have a plan!

Assuming everything is messed, here’s how I’d fix it. NOTE think this through and read Connelly – you don’t want to mess up.

I’d start on the horizontal plane of the top piece as this is one plane all exposed – just reference it to the surface plate and scrape away.

To do the bottom horizontal surfaces, you could either use the top as a reference or …scrape one side, say the side without the gib flat…lets call it Right. The scrape the other side flat, using both your reference AND an indicator. The indicator stand base is on the Right side with the indicator arm touch on the Left side (after first touching the Right side for a reference reading). Therefore via the indicator, and moving it around with the base on the Right and the arm on the Left, you can scrape the left into the same plane as the Right.

You’ve got the flats on the upper and bottom pieces beautifully scraped and lying exactly in the same plane. When you check the mating with blue, it shows complete contact on both left and right side. A few drops of oil and you’ve got the big grin over how nicely it works.

Next, you’ve got to fix the dovetail. You need to make another reference, but this one’s easy. It’s the roughly the same profile as above, but say only ½” long. First scrape the ____ surface flat and then, using a part of the slide with the least wear as a reference, scrape the / surface. We now have an angle block customer made to your dovetail.

Now to scrape the dovetail. Start with the non-gib side. This is tougher to access to scrape but hopefully as it doesn’t take the weight it’s not as worn. As you scrape, check three things 1) is it flat (against your reference, 2) is it at the right angle (check either end with your angle gauge block) and 3) is it 90 degrees to the lathe axis. For number 3, lay a piece of ground rod or drill rod into the dovetail and slide the indicator base along it with the arm against a face place…..or better still, mount the indicator to the spindle on a bent arm and rotate it 180 degrees, checking each end of the ground rod. Following me? Tougher to explain than do.

Note that the angle should not actually be 90. You want the cross fee to cut a very slight concave, maybe a thou from periphery to centre.

Now for the gib side (I’m assuming the more complicated tapered gib, figuring out to do a plain gib will be child’s play if you’ve bothered to read this far). More than one way to skin the cat, but I’d get the two dovetails perfectly parallel then fit the gib. To scrape the second dove tail, use your reference to get it flat, and two pieces of ground rod (one in each side the indicator comparing the difference between them over their lengths) and your angle gauge blocks.

The surface where the gib rested against but didn’t move against should obviously be fine. Blue the dovetail surface the gib slides against, place the top piece on and insert the gib – and then scrape the gib in. It may be that so much material has been removed that the gib will need some packing behind it or make a new gib (now that’s a PITA).

While it’s apart, fit wipers or better yet some fancy pressure oil feed system!

It’s not a small job to do (or even to describe!) but it is the right way to fix it and you are at a fundamental level engineering a higher level of accuracy and performance. You will have, at least as far as that part goes, a world class machine. This is why so many advocate reconditioning old North American iron – you end up with an incredible machine for pennies on the dollar.

Reconditioning is mostly a lot of elbow grease. There are many approaches….I tired to minimize special tooling and break it into simple steps to show it’s just a process to dispel the notion that it’s beyond anyone, and much easier than electronics or cnc controllers. Just ask if some of this is not clear.

Have fun

Geof
08-05-2005, 11:41 PM
[QUOTE=Mcgyver] ... the difference between an expert and lay person is only 5% ...

Best definition for expert I ever heard is:

"An expert is a drip - under pressure".

Stops me ever claiming to be an expert.

ty1295
08-06-2005, 02:24 AM
Thanks for posting that information. That is exactly the info I was looking for, granted I have not soaked it all in yet, I do plan to read it several times, soak it up, and at some point give it a shot.

I do appreciate the time it took to type that. i am sure others will benefit also.

MIKE JEFFERS
08-06-2005, 08:59 AM
Has this post galloped of into the distance ?
the purpose of lapping the ways on these mills is to bed them in, artificialy age if you like . Arons advice concerning lapping is safe advice
if he told you to scrape the ways he would be inundated with folks complaning they'd
followed his pointers and gouged hell out of the mill.
lapping is easy for people to do,scraping is not.

nikolatesla20
08-06-2005, 09:40 AM
Thanks for the info on scraping. I you google it you will find hardly NOTHING about scraping on the web. At least nothing useful or free. There's videos for sale out there.

I'm actually surprised that such a basic machinery technique is not more well documented on the internet. It leads me to truly believe that ppl simply do not want to share the information so they can be superior.

In that regard I appreciate the info you shared with us :)

-niko

Mcgyver
08-06-2005, 10:03 AM
the purpose of lapping the ways on these mills is to bed them in, artificialy age if you like.
don't know of aging or bedding in as a machine tool technique, but i may be wrong


Arons advice concerning lapping is safe advice
I acknowledged that if it works for some people, peace, however it is still a incorrect technique for many reasons, not these least of which its not really lapping (you need a lap and ensueing control to lap). In fact if someone tried to do this via lapping tackle it would be far more challenging than scrapping


Arons advice concerning lapping is safe advice
if he told you to scrape the ways he would be inundated with folks complaning they'd followed his pointers and gouged hell out of the mill.

or they create so much slop it damages the mill.


lapping is easy for people to do,scraping is not.
Not true imo - you are propagating the myth! skill or knowledge wise it’s no more challenging than other shop activities although it takes elbow grease. Wizard and I have both tried to point out that doing this is not really lapping, lapping is difficult to learn and do properly, and by breaking it down into little steps I've tried to show it is easy and accessible to most people.

Applying lapping compound between bearing surfaces is easy to do, but I suggest is not really relevant to the correctly creating accurate bearing surfaces. Part of the problem is that using the lapping compound holds the (false) promise of a quick fix, whereas scraping is more.


Has this post galloped of into the distance ?
I can't judge that :) The use of the compound its not the correct technique and for someone interested in the right way to do it, I took a lot time on the content, hopefully it helps some – it is the right way to do it. Others may decide pursuing scraping isn't worth the bother (that's very different from finding it too difficult) and that's fine to – ultimately what someone does with their machine is their concern.

MikeAber
08-06-2005, 08:29 PM
I submit that when Haysys started this thread I didn't have the knowledge to know the difference. Thru this thread I have gained perspective and understanding of the concepts and purpose of scraping and up to now the process I have called "lapping".

The pros are right! Smoothing the ways by the application of abrasive compounds and rubbing the bearing surfaces together to make them "smoother" is not lapping, it’s smoothing or polishing the surfaces without an accurate way to control the process. This is not the application of skills that take many, many years to learn.

I concede that scraping is not a difficult skill to learn, how to use scraping to resolve an issue of smoothing some raw machined ways is another matter entirely! As a hobbyist, enthusiast, chip sweeper or any other description you like (don't know much about machine repair), the odds of me correcting my machine's ways by scraping are not good without considerable effort on my part to learn the methodology. Learning how to do this on my machine is not an acceptable option for me.

You could compare this dilemma to the repair of your auto. If you had some problems with your motor that required repairs there could be a low cost, quick fix we can do it today option and the expensive (skilled labor) best way, 2 week repair option. Not everyone will want the expensive option (most of the pros probably would). If the low cost option was done adequately, the repair may serve the individual well, or the individual may need extensive repairs later. If the low cost or expensive repairs were done poorly, the extensive repair later scenario would prevail. If a DIY approach is taken, the results will be all over the place.

For many, smoothing or polishing the ways with abrasive compounds is the low cost, quick fix we can do today option to resolve the problem. If done adequately to rough surfaces that were otherwise machined acurately, it may serve the individual well.

For some of us, the reliability of our engine is our livelihood and a quick fix is inappropriate.
For some of us it’s just a hobby, and if it blows up, we’ll buy another.
Some of us still don’t know or want to know the difference.

I don’t have the right to tell anyone a quick fix is or is not unacceptable, it’s a personal decision.

If you, as the repairman, are told to fix it the right way, you better get out your scrappers, references and skill.

Let’s call the quick fix “smoothing” or “polishing” or something else so everyone can get back to work.

mxtras
08-07-2005, 03:09 AM
WOW! I missed a lot while I was out! I feel left out.... :violin:

I guess the only thing that has not been brought up that really should be mentioned is that 'lapping' as described in this thread will not create a flat surface.

Lapping will match surfaces by removing high spots, but it can not magically make a surface flat. It can, however, magically destroy an accurate surface. Of course, so can scraping!

Lapping is a blending and/or matching process which indicates that the parts' irregularities will be generalized into each other - assuming both are made from similar materials at similar harnesses (again – as it applies to this thread). If one surface is flat and the other has a slight cup for example, when you are done match lapping you will have lessened the cup and ruined the flat surface. You will also have likely changed the running alignment of the component but if one component was cupped to begin with, you likely gained something – they will likely run smoother with slightly less of the greatest prior error and slightly more of the least prior error…does that make sense?

As mentioned before - scraping forces you to compare to a known surface to gauge and guide the result. So if what you are looking for is flat, then you should precision grind then scrape (if it’s even necessary to scrape). If you are looking to improve the running fit and nothing else, then lap. Lapping will offer a surface which looks more uniform and smooth when compared to hand scraping. No argument there.

The end to this mystery would be to blue out a set of components against a known good master and document the results with photos and measurements. Then lap them together as discussed and re-blue and re-measure the same points and compare the results. Has anybody done this?

Scott

Mcgyver
08-07-2005, 12:36 PM
Scott, the flatness was brought up, but you had to see past my verbosity to pick up on it. I agree with most of your post, except the grinding part. scraping is superior because it holds the oil better, its my understanding that the high class machines that have one surface ground (hardened) will have the other scraped. Also, a scraped surface (after you knock off the high spots with the ground down piece of file trick) will be very smooth - the rough, frosted look is optical, although as mention you don't want a way perfectly smooth.

This is an interesting thread. I'm no way bothered or testy about the subject, heck fix your machine with a great big sledge hammer if it makes you happy :D. What surprised me was that scraping vs lapping in this context was considered a debate, like what colour to paint the living room. My background (in the hobby, i'm a finance guy by trade) is traditional machining, and if you posted something about lapping ways in one of the traditional machining forums, I don't think you'd see much diversion of opinion. I may try it for fun, get the asbestos suit on!

Anyway, its all good, just trying to help those that are interested :)

wizard
08-08-2005, 02:58 PM
I concede that scraping is not a difficult skill to learn, how to use scraping to resolve an issue of smoothing some raw machined ways is another matter entirely! As a hobbyist, enthusiast, chip sweeper or any other description you like (don't know much about machine repair), the odds of me correcting my machine's ways by scraping are not good without considerable effort on my part to learn the methodology. Learning how to do this on my machine is not an acceptable option for me.

I think the argument that considerable effort is required to scrap a surface is the one thing I object to in this thread. There are certainly things to learn but it isn't that bad.

I'm sure if you have seen this done in person the light bulbs would shine brightly in your head. Some things are just difficult to describe in text.


You could compare this dilemma to the repair of your auto. If you had some problems with your motor that required repairs there could be a low cost, quick fix we can do it today option and the expensive (skilled labor) best way, 2 week repair option. Not everyone will want the expensive option (most of the pros probably would). If the low cost option was done adequately, the repair may serve the individual well, or the individual may need extensive repairs later. If the low cost or expensive repairs were done poorly, the extensive repair later scenario would prevail. If a DIY approach is taken, the results will be all over the place.

Well if we are to talk about autos, here my perspective is that the lapping of ways is a lot like throwing lapping compound into an engines oil supply and expecting (hopeing) that it will fix a main bearing problem. Not many people would do that but yet we are doing the same thing with our machines?



For many, smoothing or polishing the ways with abrasive compounds is the low cost, quick fix we can do today option to resolve the problem. If done adequately to rough surfaces that were otherwise machined acurately, it may serve the individual well.

No the whole reason for my comments here is that it won't serve the individual well or atleast his machine. There are ways to improve those surfaces but running them together with lapping compound is not one of them.



For some of us, the reliability of our engine is our livelihood and a quick fix is inappropriate.
For some of us it’s just a hobby, and if it blows up, we’ll buy another.
Some of us still don’t know or want to know the difference.

Those that don't know or don't want to know are not likely to even be concerned. Those that want to improve their machine for any reason are likely to want an approach that does not have a negative on the machines performance.



Let’s call the quick fix “smoothing” or “polishing” or something else so everyone can get back to work.

Not so fast i have the whole week off :banana: :p

I still have a huge problem describing this activity as even a quick fix. Even when a quick fix is called for this isn't how it is done.

Twenty five some odd years ago I had the good fortune to work with a machine tool builder that frankly knew more than I'm ever likely to know about machine tool maintenance. He could take a machine apart and tell you what the last guy that worked on the machine did with it and where all the short cuts where taken. It was a very enlightening two years for me. Still with everything pointed out to me, the idea of running lapping compound between bearing surfaces was to abhorrent for even production repairs. There are things done to keep a machine running and things done to rebuild it properly, sometimes the two are at odds with each other.

Thanks

Dave

mxtras
08-08-2005, 03:01 PM
Oh, no doubt - I agree 110%, Mcgyver. I should have elaborated. I also should have read every thread carefully, but I had been away from The Zone for 5 days - I was out of practice....sorry.

During motion the ways should be running on a film of lube - not metal to metal.

Scott

MikeAber
08-08-2005, 04:07 PM
It's been interesting.

MikeAber
08-09-2005, 03:47 AM
Wizzard, ?
Maxtras, thanks for your help, your perspective is refreshing.
Mcgyver, thanks for the great photo essay and the book reference.

MACHINE TOOL RECONDITIONING by Edward F. Connelly Copyright 1954
This book is much more than I expected. - Priceless! -

Once you've read the first two chapters of this book (7 pages) you'll understand why all other methods are inferior to scraping and that everyone is not up to the task.

Read the book!

ChrisJ
08-09-2005, 07:44 AM
Hi Mike,

I did a quick search on Amazon and it did not come up with anything. Do you know if this book is still in print?

Chris

nikolatesla20
08-09-2005, 08:48 AM
Geez, copyright 1954? By now someone should be able to just scan and upload that book I would think!

-niko

nikolatesla20
08-09-2005, 11:14 AM
I do have one question though about making parts straight

I've read the notes on how they originally made straightedges and flat surfaces by using three surfaces all mated together in round-robin style. It makes sense of course.

But my belief has always been that yes, if you took two edges of something and worked them together, the friction would over time cause those two edges to completely match up. I'm not talking about machine accuracy here; I'm talking about just trying to make one edge straight along with another. For example, say you just wanted to make a straight edge on something. Say that one edge was the only edge you cared about (you aren't trying to align it with anything else on the part, maybe say you just want a straight edge to use for marking or something). Why couldn't you simply take two pieces of that material, and basically mechanically fasten them so they rub together using a reciporicating mechanism, and then put in some lapping compound? Over time any high spots between the two surfaces would be "sanded" down until both surfaces almost had full contact. Hence, making the edges perfectly straight and flat. Of course they would not be flat to some reference point, but only flat in their own right (And they would be flat to each other).

I keep thinking this should work fine, but obviously in the past they chose to use three surfaces.

What am I missing?

I know that ball bearing making machines use a technique similar to this; they have two rotating grinder discs, and the balls drop down in between them, and then rotate and get ground at the same time. Then they move around because a disc inside forces them side to side (or something like that) so eventually the whole outside surface it round and accurate to the width of the grinding discs.

-niko

MikeAber
08-09-2005, 11:17 AM
I purchased a used book (9th edition 1974) in very good condition on Amazon.com.

No fancy color pictures, excellent illustrations and descriptions of everything in terms I can understand. This is a repair manual that assumes you are an apprentice. Very technical, yet not intimidating - does that make sense?
Don't bother buying any other book on scraping or machine tool repair, as Mcgyver said this is the tome.
Powell’s has new reprints of this book.
http://www.powells.com/cgi-bin/biblio?inkey=4-1114266612-0

Mcgyver
08-09-2005, 04:02 PM
niko, I think what you are missing that in generating a flat or square, A, B & C are compared to each other, not worn against each other. Guy Lautard in one of the bedside readers describes the process. Lets say you could wear two pieces away until there was complete contact, there would be no reason for it to be flat, ie. convex/concave.

the idea of wearing two pieces until they are a perfect mate I assume requires them to be the same length. In this case lapping would tend to remove more material from the middle as it tough to avoid there being more contact there per stroke.

for the original generation of flats or squares, the A, B & C thingy wasn't a choice that was made, its the only way to do it. Mike's probably finished that book by now and can pipe in and give the master mechanic explanation :)

MikeAber
08-09-2005, 04:07 PM
Mike's probably finished that book by now and can pipe in and give the master mechanic explanation :)

OUCH!

Geof
08-09-2005, 04:50 PM
An example of generating conves/concave surfaces by lapping two parts together is the preparation of mirror blanks for small astronomical telescopes When two glass discs are lapped together you generate perfectly matching convex/concave surfaces which is why astronomical telescopes could be made long before sophisticated machinery.

I think the one time you do actually lap flat things against each other in threes and generate a flat surface is the preparation of optical flats in glass. Also ball bearing manufacture where the balls are lapped between two large discs is more or less three surfaces lapping against each other. In this case the surface of the discs become flat and the balls all the same size.

nikolatesla20
08-09-2005, 04:58 PM
niko, I think what you are missing that in generating a flat or square, A, B & C are compared to each other, not worn against each other. Guy Lautard in one of the bedside readers describes the process. Lets say you could wear two pieces away until there was complete contact, there would be no reason for it to be flat, ie. convex/concave.

the idea of wearing two pieces until they are a perfect mate I assume requires them to be the same length. In this case lapping would tend to remove more material from the middle as it tough to avoid there being more contact there per stroke.

for the original generation of flats or squares, the A, B & C thingy wasn't a choice that was made, its the only way to do it. Mike's probably finished that book by now and can pipe in and give the master mechanic explanation :)


Thanks, 'tis what I wanted to know! Yep I knew that they didn't rub the things together for A B and C I was just wondering why rubbing two parts together wouldnt make them flat.

-niko

sblack
12-27-2005, 10:08 AM
I am looking seriously into the IH mill and have discovered this discussion in my research. I have read through enough of the Connelly book to understand the principles behind scraping and I have had some precision grinding done on an old lathe so I think I have some idea about what is (was) being discussed but I have a question: What is the issue with the ways on this mill? Are the ways simply milled or are they ground? If they are ground is it simply a question of knocking off some burrs? Or are there fundamental alignment problems?

While scraping in theory does not seem that hard, there is an initial investment required that could be substantial i.e. surface plate, indicators etc. If there were ways that were not parallel or planar I think it would be an intimidating thing for a guy to do on a new machine. But if the overall alignment is good and it is just a question of knocking off some high spots to get good contact I would not be too apprehensive about it.

So if anyone can accurately describe to me the real problem with the ways as they come out of the box it would be very helpful. Thanks

wizard
12-27-2005, 01:02 PM
I am looking seriously into the IH mill and have discovered this discussion in my research.

The IH mill is a nice mill there is no doubt about it. I'd have to say it is the ideal machine to CNC at the low end. One shouldn't confuse it with an industrial machining center but I don't think that is an issue on these boards.


I have read through enough of the Connelly book to understand the principles behind scraping and I have had some precision grinding done on an old lathe so I think I have some idea about what is (was) being discussed but I have a question: What is the issue with the ways on this mill?

I'm not sure the ways are as much of an issue as the suggestion to lap them to increase performance or ease of axis movement. Lets face it, the mill is Chinese and built at a price point to support a cdertain market segment. It is a good machine for the money but it is not something to get excessively excited about either.


Are the ways simply milled or are they ground? If they are ground is it simply a question of knocking off some burrs? Or are there fundamental alignment problems?

Having no familiarity with the manufacture and only having a brief glipse of the ways at one of the shows I suspect that they are milled or roughly ground.



While scraping in theory does not seem that hard, there is an initial investment required that could be substantial i.e. surface plate, indicators etc. If there were ways that were not parallel or planar I think it would be an intimidating thing for a guy to do on a new machine.

Everybody has their first time. The thing with scraping is that you get better at it as you age. Well atleast until your eyesight and back give out.



But if the overall alignment is good and it is just a question of knocking off some high spots to get good contact I would not be too apprehensive about it.

I can only give an impression here and that is that overall the machine is not that bad.



So if anyone can accurately describe to me the real problem with the ways as they come out of the box it would be very helpful. Thanks

Rough - I think that about wraps it up in a nut shell. The reality is this thread got away from discussion of the ways and drifted into what was the right way to work on the ways. The reality is one needs to look at what you are buying for the money. Even with Chinese rates one can not expect to get $10000 dollars worth of machine tools new for one tenth the price,

Thanks
Dave

MikeAber
12-27-2005, 06:15 PM
I owned two of the gear head mills, a Harbor Freight round column and the Industrial Hobbies Mill. Both of them had MILLED ways and accuracy of the ways was not an issue for me. The HF mill's ways were OK; the IH's ways were very rough. Both of them also have issues with flatness of the tables and many other issues compared to an industrial quality machine. I consider these machines stepping stones and for some these will be all they need. It is possible to do nice work with this level of equipment but not easily. The biggest problem is the rigidity between the column and the base. I still have the IH mill and am using it for manual operations. If I could do this all over again, I would purchase a turret head Bridgeport style mill for manual operations.

MikeAber

jderou
05-02-2006, 06:06 PM
Been reading intently, good reading! I still don't understand a couple of things. Number one, how do you scrape the saddle way such that it is perfectly perpendicular to the knee/column way? I haven't heard anyone mention scraping a right angle reference tool yet. If a right angle tool does need to be scraped, how the heck do you reference it? and if I had bought a right angle reference, why wouldn't I use that for a way scraping reference instead of scraping a reference tool. And the biggest question in my mind, is why you cant grind a flat reference tool on a surface grinder? I would think this would be plenty accurate place to start.
I am preparing to scrape my BP ways, and I am trying to get as much info as possible before I start. I have wear in the center of my y-axis. I know I can get it flat, but getting it horizontal is the hard part.
Joe

ZipSnipe
05-02-2006, 06:29 PM
No Doubt this is absolutely the best post on this forum.... BRavo gentlemen, Bravo

Mcgyver
05-02-2006, 08:39 PM
Zip, its a good subject that doesn't seem to get much coverage on the net, maybe it's getting bumped will bring in some more perseptive from some of the pro's here. Joe those questions so staccato, not sure where one starts and one stops. :) here's the verbose response….

Getting things square. Lautard in one of the bedside readers gives a good description of generating a square - interesting but not something I'd considered doing so until your question of getting the knee square to the column. Highly accurate (to say a tenth) 6” squares are reasonably priced, but how do you come up with a 18 or 24 inch square - commercially it might cost as much as the restoration project (like the big starrett granite square). I’d probably give generation a shot, will it looks daunting, you are making the square out of thin stuff so it shouldn’t be that bad. Restoring that mill is both a major undertaking and the quality of the work you do on it is the foundation to accracy thereafter- so it may be worth going the distance.

I’ve not done it, but if I were facing the task I’d scrape the column with a reference and indicator, then the knee to the column. Then using a combo of reference, indicator and big 18” home made square get one of the saddles dovetails perpendicular to the column. It doesn’t sound like an easy job because the parts are heavy, but in approach it’s the same as most scraping – pick a reference, bring things into relation to the reference. Better yet, buy Connelly’s book and learn it from a pro, although as Robert Bastow said, Connelly's probably the only guy that was every able to stay awake through the entire book.

As to why you scrape a reference vs grinding, lots of reasons. Most grinders don’t have the capacity and the magnetic chuck itself distorts the work are two obvious ones. You are holding a tenth or so over maybe 24” or longer, even a big cross section of cast iron gets pulled out of shape on the chuck, and that’s if you have a big enough grinder. For example, put a tenths indicator on your lathe and lean heavily on the end of the bed and watch it move – and the reference is a lot more “flimsy” than the lathe bed. I would guess commercial ones are done on a grinder then finished by scraping to surface plate, but hey if you got a 24” grinder, go to it :D and check it with blue and the surface plate.

A lot of talk so far on reference has been dovetail ways which have an angle less than 60, not square – so don’t’ really understand the “why wouldn’t I use the 90 reference I bought” question. You can buy a way reference, just not sure where and they’re expensive. When I say reference, I’m talking about something like the pair in the grey box on page 2 or the camelback, not common items at the local tool store.

Also just for clarity, when scraping, the part being scraped is compared to a reference – that reference may be a surface plate, precision square, precision flat, camelback or the matching machine part that you just scraped flat. Point is, if you bought a right angle reference, and you’re using it for scraping, it’s a scraping reference in this context. It’s just given very high precision is very expensive to buy, and the reference needed in are large (even more expensive) but they can be very accurately home made.

take lots of photos of the bport job

jderou
05-03-2006, 08:37 AM
Here is a pic of my current situation. Wear in the centers, more so on the right side. After looking at it last night I came up with a game plan. I think I can assume that the very front of the ways and the very back are in good shape. So I can start scraping the right hand side using a flat reference and using a dial indicator set up on the front and back of the left hand way to compare the front and back of the right hand. Then once I get that flat and parallel to the left hand 'corners', I can start on the left side.
What do you think?

jderou
05-03-2006, 02:31 PM
I grabbed a couple pieces of ~ 2' pieces of ground bar stock and checked it on a granite surface, and now I know why you can't just use a ground piece of bar stock. So I guess I will be scraping a straight edge. Iron is not an easy (or cheap) thing to come by, is it acceptable to use steel?. I am thinking about taking a piece of 1 x 3 x 24 cold rolled, machining it to fit in the dovetail as was mentioned earlier, then bolting to another piece of stock to make a T-shape, then scraping the top of the T.

Geof
05-03-2006, 02:46 PM
If you machine cold rolled bar you will find it distorts into all sorts of wonderful shapes because it has a lot of internal stress from the rolling operation. Hot rolled bar does not distort as much but even this would probably distort far too much for what you plan on doing. To use steel you will be faced with stress relieving or normalizing after a preliminary machining followed by a finish machining or grinding and even then it may be no better than the ground bar stock you checked on a surface plate. Cast iron is used for straight edges and surface plates for the reason that it does not move as much as steel.

MikeAber
05-03-2006, 06:08 PM
Hi Joe,

Do yourself a favor, purchase a copy of this book: MACHINE TOOL RECONDITIONING by Edward F. Connelly Copyright 1954.

It explains the procedural steps necessary to accomplish this task, what references are necessary, and how to setup and use the references to monitor your progress.

MikeAber

jderou
05-04-2006, 08:53 AM
Out of curiosity last night, I took a sharpened file to the way to see how hard it was going to be. I put my weight into it, pushed, nothing happened! A quick look at my owners manual confirmed it has chromed ways. So now what? It appears that it isn't worn through the chrome anywhere, so in theory the metal underneath should be in good shape. Is their a way to strip chrome?

mxtras
05-04-2006, 10:22 AM
.....Is their a way to strip chrome?

With a grinder. There is an electrolisis method also but my guess is that you don't have the equipment to do that and it is my understanding that it is increasingly difficult to find folks that do.

Scott

nikolatesla20
06-26-2006, 02:17 PM
Quote from Wikipedia:



The man who scrapes is called a "hand". It is done by using a precision surface such as a surface plate or a straight edge as a standard (a straight edge in this context is not a ruler it is a miniature surface plate of extreme accuracy). A professional scraping tool will be a special made tool, not an old file. The standard is coated with a very thin coating of some material such as Prussian blue. The work piece and standard are touched together by gravity alone and the high spots on the work piece will be colored by the dye on the standard. These high spots are scraped off and the process repeated until there is an even spread of high spots which total about 60% or more of the surface area. If desired the surface can then be “Frosted”. A surface prepared in this way is superior to any machining or grinding operation, although lapping can equal it. Grinding and machining stresses the metal thermally and
mechanically, scraping and lapping do not.

-niko

Mcgyver
06-26-2006, 04:34 PM
niki,

the problem with that quote is its out of context - what is being called lapping in this thread is a misnomer, it's NOT lapping as it relates to its commonly understood meaning and what author in your quote is comparing scraping to. Lapping uses a lap against the workpiece. It can be an exceptionally accurate technique. There is however a lap, and the shape of the lap however is controlled. applying compound between two pieces of work is not lapping, as the word/technique is generally understood amongst people skilled in metalworking, or at in minimum it is not a correct lapping technique. so while the wiki is fairly accurate (not a given with wiki's) that quote is out of context to the thread imo.

I've done both flat and cylindrical lapping as well as scraping. One of the themes of this thread I think is that lapping or scraping are not competitors, they are different processes, mostly used in different situations.

Kipper
08-11-2006, 05:02 PM
http://img162.imageshack.us/img162/9959/dawningmm4.th.jpg (http://img162.imageshack.us/my.php?image=dawningmm4.jpg)

That description Mcgyver gave earlier helped a lot :beer: I often wondered and once I saw that (in my head) it made complete sense. Thankyou bud!

Cruiser
08-12-2006, 10:48 AM
Jderou, Cast iron moves around some and is somewhat plastic, if your bed is chrome then i'd suspect more of a settle or sag than wear. even the largest of machines with a huge cast iron body must be leveled and aligned and kept that way as they can and will sag settle and move with warming and cooling and gravity. If it is some settling then you may be able to coax the casting back to where it should be. when i set up my new IH mill, to the table, the first check was the bed for twist and it was close to .018 maybe more, i pulled it into tension the oposite way and let it rest for a few days then in several sessions got it true to within half a line on my sterret machine level, it is staying put for now but subject to change. what would i have had i started scraping or lapping or grinding or ......!

Nic Scheepers
07-07-2007, 03:04 AM
Hi there,

This thread has most probably been forgotten already but I tell you one that learned me the most. I have read more or less this whole thread and could not get myself to decide what to do .

My machine(ZAY7045FG) came with very rough gibb strips and one was buckled a bit. This told me I had to do something to improve my machine a bit. Now, learning scraping is going to take a whiile and I cannot get hold of any lapping compound so what to do now.

I decided that lapping with very fine grit sandpaper flat on a piece of glass would do the trick as I woulkd not take off too much, and if I did the gibb strip would be easier to replace than the machine.

I started to take apart the whole machine to prepare for the operation and then started my lapping(sanding) of the gibbstrips. I did not take of too much as I still needed the pockets for the oil. What I did thought when reading the thread was that if I could lapp the strip untill it is very flat, the suggestion of etching some grooves in a diamond pattern was very tempting.

I then washed the whole machine thoroughly and started putting it together again. Now here is where the actual lessons I learned happened. I got to know my whole machine from back to front to the finest detail. I learned I should tram my mill after putting it together, and by the way how to set up my lathe properly, through my wanderings on the net. This was the most learning experience I got. Do not just see this excersize as a mere lapping of the ways or gibbstrips but as a very good learning experience. I now know why they say it is the operator who is good or bad and not the machine you are working with:)

So do this just for the experience. I did not have any experience in chipping metal before but now a whole new world has opened up.

Now that the blabber is past us I have a question. Nowhere in my wanderings I could find a thread which could tell me how much slack or backlash is permissable in a machine. I know you are going to say "none" but the fact is with a hobby machine there is always a bit of slack. I do have a setting screw that I can set the slack of the feedscew but after tightening it a lot I discovered I still have a bit of slack on the bearings(0.03mm). Looks to me I am going to sit with the 0.03 mm backlash, how much is it on your machine?

Regards

Nic

mxtras
07-13-2007, 02:31 PM
This question requires a long answer, but in a nutshell, in any gib arrangement you will have some backlash - you have to unless you want to wear out the ways quickly.

.03MM (.0012") for a precision mill would be a football field, but for a hobbiest it is extremely acceptable in my opinion.

I have more than that in the middles of travel on my second-hand Bridgeport, so I run my machine at the ends instead of setting up in the middle (most of my parts are only a few inches long). I will run for a few weeks at one end, then move the set up to the other end in attempt to wear the machine evenly. I do the same for the saddle - I run near the back, then near the front. I have a central lubricator and I lube the ways almost every cycle. The ways on my BP are worn in the centers but they are chrome, so I chose to deal with it until/unless they get worse. I work around the "sloppy" regions of the machine.

Scott

SMW Precision
07-15-2007, 11:43 PM
Hi there,

I do have a setting screw that I can set the slack of the feedscew but after tightening it a lot I discovered I still have a bit of slack on the bearings(0.03mm). Looks to me I am going to sit with the 0.03 mm backlash, how much is it on your machine?

Regards

Nic

Nic,

Yours is at the bottom range of normal in backlash. Most machines will have between 0.002 to 0.006" of backlash. It is not possible to eliminate, with standard lead screws.

Nic Scheepers
07-16-2007, 12:13 AM
Thanks MXtras,

I just wanted to get the feel of what is acceptable and what is way out. Your answer tells me precisely what I needed to know.

Thyanks a lot.

Regards

Nic

Oldmanandhistoy
09-03-2007, 06:04 PM
Hi all,

I came across this thread quite a while ago now and read some very interesting posts by some obviously experienced scrapers. I added it to my favourite cnczone threads so I could easily find it and use it as reference. To cut a long story short I recently bought a Chinese bench top mill which was in need of some serious scraping. Many years ago now I was given a demonstration by my grandfather who actually did scraping for a living before he retired so I had a good idea of the basic technique. Because I have not read much about the method to scrape a mill I decided to use my initiative and gave a lot of thought as to how I would get the job done. Anyway in another thread I was asked how I would proceed and gave a basic description of how I am doing things. I was kind of hoping some one with the necessary experience might notice and jump in if anything needed correcting. I’m adding the post from that thread here and I hope that some of the posters in this thread will come back and give their opinion on my method. I’ve added some pictures of my effort for your scrutiny also they are from as came, first blue, about half way and the finished part (I was aiming to only remove as much metal as was necessary so as not to need new gib strips for all axes).


DISCLAIMER: I will describe how I did my scraping but I am FAR from being an expert so the methods I used may not be correct. I did think carefully about how I would accomplish the task before I touched anything. It would be nice if someone with experience could read this and correct things if necessary.

In brief how I did my X and Y was to start by bluing up both sides of my saddle using the surface plate as a reference. I then scraped the flattest side of the two sides. Then I placed the saddle back onto the surface plate with the scraped side down. With my DTI I found the lowest point on the four corners, set my DTI to zero and then went back to the other three corners and scraped a reference mark to zero with my DTI. Using my reference marks and the surface plate I scraped the other side. Now I had a reference for my table and the base of the machine.

I did the table next; first checking the table surface for flatness. To do this I used my DTI set to zero on the surface plate with about a 150mm reach. I moved the DTI base to various points on the table and swept an arc watching for any deviations from zero. I am pleased to report that my table was within 0.05mm. I double checked the table with my camel back, from end to end and then across the corners but if you are careful with the DTI this is not absolutely necessary imho. I then placed my table upside down on the surface plate. Again using the DTI I found the lowest point on both ways and set it to zero. Then I scraped reference marks to zero every 100mm on both ways. Using the saddle for bluing the ways and the scraped reference marks I scraped in the table. I again used my camel back a couple of times on the ways to check full length of the table to make sure they were straight but again imho this is not absolutely necessary.

The ways on the base of the machine I did in a similar way to the table again using the saddle to blue the ways and the DTI set to zero on the surface plate to check overall flatness and that both ways were on the same plane to each other.

I hope all that made sense but if not please feel free to ask me to clarify a point if needed.

All this scraping take a considerable amount of time and effort but imho is well worth it; how are you going to make accurate parts on an inaccurate machine. Don’t get me wrong I am not saying that the machine is not accurate enough as it came out of the box but like I said in an earlier post I am a perfectionist by nature so wanted it to be as accurate as I could possibly get it. Also I gave a brief description of how I did it; there is more to it than I described.

One last point; by scraping the ways there is a possibility that the gib’s will no longer be wide enough and may need replacing.

John

While spending the hrs I have so far and with a few more to go I was wondering how much difference all this work would make to my new mill and am I being too fussy taking the surfaces to within +/- 0.005mm (0.0001968498”) (some were +/- 0.03mm (0.001181099”) before I touched them) and the table ways were a milled finish. :eek:

If you are interested you can go here http://www.cnczone.com/forums/showthread.php?t=40213&page=4 and see the other posts about scraping that I and another member have exchanged. It would be interesting to know what you folks make of them.

John

Yrrab
09-04-2008, 03:46 PM
Have just read the thread on lapping and scraping and am overawed by the knowledge displayed. What I have learned is not to even attempt the exercise but rather to look for a professional. I have an old Graziano 180 with all its bells and whistles still working but would like to improve its accuracy. First steps have been to fit a new chuck and to have the screw on the crossfeed reconditioned (needed polishing and burr taken off the nuts). What is the recommended way to check for wear on the bed? Maybe it may only need adjustment to the gibs and adjusting screws. Any advice will be most welcome!

Yrrab
09-04-2008, 04:10 PM
I have read much of the thread describing scraping and lapping. I now conclude that scraping is the physical removal of highspots revealed by bluing using a highly accurate straight edge whereas lapping is the rubbing of the bed ways with a shaped block of something. My questions are: in the case of scraping what implement/substance is used and in lapping is some form of grinding paste used?

Oldmanandhistoy
09-04-2008, 04:30 PM
My questions are: in the case of scraping what implement/substance is used and in lapping is some form of grinding paste used?

Hi,
For scraping tools look here. http://www.cnczone.com/forums/showpost.php?p=95535&postcount=26

For lapping paste here. http://www.newmantools.com/lapping/time.htm#green

John

Yrrab
09-04-2008, 05:50 PM
Very greatful to John "oldmanandhistory" for the requested information. Slowly the cloud of mystery around the topic of scraping and lapping is lifting.

However now that I am starting to understand could someone explain the teqniques involved with "V" beds? My old Graziano has seperate bedways for the saddle and tailstock - one side is a "V" and the other is flat. I suspect that the bedways of the tailstock have little wear.

Barry (South Africa)

IHCNC
09-08-2008, 03:09 PM
Hi Folks;
Although in the last year and a half we have only sold our mills with ground ways it might be interesting to know how to scrape V bed ways on a lathe.

skullworks
09-28-2008, 12:30 AM
I wish MY IH mill had ground ways. :confused:

That IS the way they are advertised on the IH website, it appears however that the asian supplier never got the memo. Mine arrived with just crude machining of the ways, nothing ground but the table top and side. :mad:

Had I seen it that way on the truck it would have never been off loaded, but I was not there when it was delivered. ( The Y axis ways were visable thru the missing portion of the shipping crate. The DRO box only made it because its tape stuck to some of the crates tar paper lining - 1/3 of the crates floor was missing. )

IHCNC
09-28-2008, 07:35 PM
Hi Greg;
You bought the mill and DRO in 03/17/2007. At the time you told me about the crate, but said everything was fine and that you loved the mill. After a year and a half of owning the mill if you are not happy with something please feel free to call. As always we will try to help our customers out any way we can.

Dr Not
11-25-2008, 12:10 AM
Well I have to say that this is one of the more interesting, and certainly information packed threads that I have read on CNC Zone.

Now I will pick my New IH Mill up tomorrow morning and I am expecting the ways to be ground as is advertised on the IH website. However, after reading some of the posts here it makes me wonder if ways that are ground are ready to begin work. If it is necessary to scrap the machine or lap the ways before even putting it into service.

If Gene or Tommy from IH could comment about this it may give me clearer direction. Well for that matter if anyone could clear up the question about ground ways either needing improvement by lapping or by scrapping before putting the machine into service then I would be very appreciative.

LUCKY13
11-25-2008, 04:51 AM
You want have anything to worry with on the new mills. Clean it (all the shipping grease/wax) and lube/oil it.



Scraping is someth8ing that should be done by a profesional anyway. Although many have went through the trouble to learn how to scrape a machine, it is something that if not done right can/will ruin a good machine. Now after you wear your machine out (many years of hard work), scraping would be a good way to repair it.



With the hardened and ground ways of todays IH mill it is ready to rock when you get it (except for cleaning & oiling & ajustments).

Lapping is something that helped the older machines. And although many statements are correct in this thread, when done right, lapping/polishing the ways on the "older machines" was something that helped, and was not a danger when done right. The ways on the newer machines are good enough they dont need anything in the order of reworking.

Get it, clean it, set it up, and enjoy it.


Jess

MikeAber
11-26-2008, 02:06 PM
[QUOTE=Dr Not;530938]Well I have to say that this is one of the more interesting, and certainly information packed threads that I have read on CNC Zone.

Now I will pick my New IH Mill up tomorrow morning and I am expecting the ways to be ground as is advertised on the IH website. However, after reading some of the posts here it makes me wonder if ways that are ground are ready to begin work. If it is necessary to scrap the machine or lap the ways before even putting it into service. QUOTE]

New machines are much improved compared to my 8 year old machine and shouldn't require anything other than proper maintenance.

Enjoy,

MikeAber

Cruiser
11-28-2008, 11:33 AM
RELAX DR ! Most of this stuff is old mat'l and obsolite with the new machines. My understanding is the new machine was ground on a new machine and that the work on them was up to par at least.
I am refering to the new 12"z model, mine is the 10"z ver 3 and it needed lapping to make up for a machine that milled it allong with many thousands of other parts and never had any maintanance. I would venture a guess that the operators also ran the cutters till they glowed in the daylight ~ and quality control was two words they have had to learn but they didn't know why.
there are lots of old machines floating around and many people have been looking here and asking questions so this was brought to the header for them. It should be trimmed of all the excess chat and just leave a solid info base with bold titles so non of this is confused with the new machine. I WISH I HAD ONE OF THE NEW 12"Z's !

Freddy Warbird
09-08-2009, 06:29 AM
I don't see how a man could maintain his sanity if this was his life. Damm.. that is a big area to cover, then move on to the next one. :eek: Maybe this is an apprenticeship, and this fellow will move on to other tasks after some time..Interesting skill though.
YouTube - Kitamura Machinery - Hand Scraping Techniques on a Horizontal Machining Center

BlackMoon
09-10-2009, 12:08 PM
Amazeing video I allways wanted to see how its done! so thats how that pattren is made I thought it was like the grain of the cast iron or something.

LUCKY13: I don't believe (or heard anyone else say anything about) the ways being hardened. only the gears are hardened

Also, I discovered that the *bottom* way of the table itself is NOT ground.
All other ways are however. the *cough* person who got me my IH clone mill is seeing if he can get me a fully ground table however, and is asking the company to fully grind his tables for the future.

pete from TN
09-11-2009, 02:08 PM
So is that long odd looking block he slides across the surface applying some kinda layout fluid to show the high spots? I see obviously how he is scraping to the blue areas I think but that video makes it seem simpler than I thought it was. There must be some master guage that they use to verify flatness no? neat to see someone actually doing it tho... peace

ihavenofish
09-11-2009, 03:12 PM
So is that long odd looking block he slides across the surface applying some kinda layout fluid to show the high spots? I see obviously how he is scraping to the blue areas I think but that video makes it seem simpler than I thought it was. There must be some master guage that they use to verify flatness no? neat to see someone actually doing it tho... peace

the block he rubs accross the surface is the master guage. its coated with blue, and it rubs off onto the high spots on the bed.

its a somewhat localized method, so they probably use something to guage overall flatness.. perhaps lasers.

Cruiser
09-11-2009, 09:28 PM
I'd bet this machine had been ground, and the scraping is for oil retention. There would be a standard off the side somewhere that had a thin coat of prushion or high spot blue rolled out fine, The blue is non drying and stays for as long as needed, then the Hand (person doing scraping) applies his straight edge (tool in hand) to standard to pick up a fine smear of blue. It is then run on machine to blue the highlites, then the highlites are scraped off for the pattern. When done the blue should be very even and show pattern in a very uniform spread over the whole of surface. I doubt that what this person is doing would satisfy an old school master Hand. but it gets the job done.

http://en.wikipedia.org/wiki/Hand_scraper

Javerh
12-21-2009, 07:07 AM
This is a very interesting thread.


the block he rubs accross the surface is the master guage. its coated with blue, and it rubs off onto the high spots on the bed.

its a somewhat localized method, so they probably use something to guage overall flatness.. perhaps lasers.

I ran across this interesting site:
http://www.yasda.co.jp/la_English/takumi/takumi02.htm

The pictures are in a strange order, but I think I understood the process. They start by grinding the way guide. It is then lapped with diamond paste. Then it is scraped flat. Finally, the angle of the surface relative to other surfaces is checked with an autocollimator. If the angle is sub par, the scraping is redone to improve perpendicularity.

A quick check on ebay shows that autocollimators cost something like $200 to $1000. It seems this kind of an instrument could be extremely useful in inspecting the ways on a mill or even tramming the head! Has anybody got experience in using these?

Mcgyver
12-21-2009, 07:37 PM
I'd bet this machine had been ground, and the scraping is for oil retention. There would be a standard off the side somewhere that had a thin coat of prushion or high spot blue rolled out fine, ]

no way that is oil retention or what's called frosting, its too deep. Prussian blue is what you thinking of. What would satisfy an old master was the number of bearing points per square inch. The only thing I argue is that the spotting tool is a small...should be most of the size of area being scraped

reading these last few pages, I'm struck by the number of comments and opinions proffered on lapping and scraping done so without the benefit of experience :D.

I've a a surface grinder but will often do gauge work by hand via scraping - i'll go so far as to say it is often easier achieve a higher level of accuracy with scraping. So far as machine tools are concerned, i think you're deluding yourself that because the surface is ground its either accurate of better than scraped. There is no guarantee a ground surface is flat and besides, flat is the easy part....its getting all the surfaces in the correct relative relationship to one another that is difficult....that doesn't rely on the accuracy of the grinder that relies the accuracy of the set up and operator.

Scraping is a simple skill that will greatly increase your capabilities; well worth learning. for fun, here's a few recent projects.

This is a toolmakers cube square and parallel all over to a tenth. Do you know how to grind it that with just a mag chuck? I do and i've got the grinder....but I can get it as good or better with scraping....and probably faster

http://i785.photobucket.com/albums/yy132/michael01000/scraping/finishedscrapedcube.jpg

http://i785.photobucket.com/albums/yy132/michael01000/scraping/squarenesscopyright.jpg

Here are some V gauges...gauges instead of blocks :). yeah we've all got tons on V blocks but these were made to fit a specific V way and are matched such that 10ths indicator doesn't move on any of the 4 sides with its sitting at 45 on a sine bar. Custom size is one reason for making and scraped vs grind has the advantage that grind surfaces make terrible spotting tools

http://i785.photobucket.com/albums/yy132/michael01000/scraping/DSC_1671Large.jpg

ground up T&CG restoration...scraping the saddle. this Taiwan Chevalier was out over 2thou on the long saddle V ways....thats not wear its poor construction. You can grind one side of one V flat....and then start puzzling on how your going to get the 2nd 3rd and 4th in the perfect relationship to the first. That's up the operator or set up man and will have nothing to do with the accuracy of the grinder. Like any form of fine bench fitting, tough for Chinese/Taiwan low cost production to compete with what i can do at that bench so far as accuracy and quality is concerned. Perhaps accuracy has improved, but its nonsense to conclude that because the surface is ground, the bearing surfaces are accurate and well fit to one another

http://i785.photobucket.com/albums/yy132/michael01000/DSC_1619Large.jpg


double V ways are tricky. The matched blocks are used to check the angle on each V and then used in pairs with a master precision level to make sure one isn't going up hill to the other, and then on each V with indicator set up to measure the distance between the V's, ie no converging

http://i785.photobucket.com/albums/yy132/michael01000/DSC_1622Large.jpg

Set up for measuring distance between V's. that's a tenths indicator, took lots of practice to get consistent readings with such a flimsy set up

http://i785.photobucket.com/albums/yy132/michael01000/DSC_1644Large.jpg


Anyway, I threw those up to give some ideas and comments from one who actually has done a lot of scraping :D

ViperTX
12-21-2009, 08:10 PM
Thanks McGyver....that was very educational.

You should think about doing a video on a small project. I think that it would be quite educational, you might also be able to make a few bucks from it.

Thanks,
Paul

grf
12-29-2009, 04:21 AM
i am new in the forum and also in the machining hobby. i recently bought a machine (bigger than i should) and try to find my way around.

i never thought that even today things would be done in such a traditional way (scraping). i would imagine that by today some sort of hitech solution would be found to deal with these things. it is at least amazing that a flat surface is constructed in such a way.

i have a question though if it is not out of topic. since there is a lot of talking about bearing surfaces wouldnt it be easier or better or maintenance free (or easier) to convert to linear bearings? where i work there is a big cnc (for woodwork) and everything on it moves on linear bearings so it make me wonder. is there a reason that they are not used (apart from cost maybe)?

again great thread highly educative.

Javerh
12-30-2009, 02:33 AM
grf, telescope mirrors and lenses can be polished and squared on atomic level. The resulting surface is near perfect. However, the cost of the operation is mind boggling. Furthermore, a guideway made in this fashion would require further work to improve oil retention. Scraping is the cheapest, fastest way to straighten a surface without ruining the oil pockets. I read somewhere, that there have been attempts at making a CNC scraping machine. It would use machine vision and dye applicator to replace the hand. I doubt such a machine would be very versatile.

Linear bearings are superior to box ways in almost every way. They are easier to implement and allow the use of higher speeds. Apparently, their greatest weakness is their dynamic stiffness. On linear bearing surfaces the loads are carried by very small portions of the rolling elements. There is very little oil between the load bearing parts. The rolling elements are very rigid and have only minuscule deflection. On box ways the contact area is larger and the oil layer is thicker. The result is similar amount of deflection. When the ways start to vibrate, a thicker layer of oil can dampen the vibrations faster. Linear bearings will ring out longer. Vibration can shorten tool life, reduce surface accuracy and increase surface roughness.

grf
12-30-2009, 04:22 AM
so if i go it correct linear bearings would make the trick but they would fail sooner under lets say heavy loads or during a crash or something like that compared to a dovetail or boxway. what is the difference between the boxways and the dovetail ones? i searched the net but the results are not very clear they look like a square (a plane surface and two parallel for alignment)is this correct?

thank you for your replies. this forum is very helpful

Mcgyver
12-30-2009, 07:57 AM
i never thought that even today things would be done in such a traditional way (scraping). i would imagine that by today some sort of hitech solution would be found to deal with these things. it is at least amazing that a flat surface is constructed in such a way.
.

That premise is flawed - that somehow if it hasn't been developed in the last 50 years its no good. There are other ways of getting this flat, some old, some new....in eveluating them or observing their merits there is no best before date. Turning's traditional but is still used, right? It works. the advantage scraping has is that's its comparative; distribute one known quality master and hundreds almost-as-flat copies can be made....all from a low tech, low cost reference flat.

the other thing to appreciate is that getting something quite flat is not trivial, for a given flatness, the bigger/longer the area the more difficult it becomes. Maybe there is a cheap, better high tech way of going about it.... waiting for you to invent it :)



i have a question though if it is not out of topic. since there is a lot of talking about bearing surfaces wouldn't it be easier or better or maintenance free (or easier) to convert to linear bearings?


On what do the linear bearings sit on? Does that surface not need to be exceptionally flat? how are you going to get it so?

I lack expertise to do a decent treatment of comparing the two, however a few obvious things must be: cost (creating precision bearing surfaces is far from free, I'm not sure which way wins the cost war). Probably more important is loading and rigidity. Other things being equal, I'd think there is an advantage in the large bearing surface a box/dovetail/V way offers vs the very small area of contact recirculating balls offer. Anecdotally I see things like high end jig borers (is there a more expensive/exact machine tool?) with scraped ways not linear bearings....like all design, it depends on what the machine is called upon to do

BobWarfield
12-30-2009, 12:14 PM
On what do the linear bearings sit on? Does that surface not need to be exceptionally flat? how are you going to get it so?

I lack expertise to do a decent treatment of comparing the two, however a few obvious things must be: cost (creating precision bearing surfaces is far from free, I'm not sure which way wins the cost war). Probably more important is loading and rigidity. Other things being equal, I'd think there is an advantage in the large bearing surface a box/dovetail/V way offers vs the very small area of contact recirculating balls offer. Anecdotally I see things like high end jig borers (is there a more expensive/exact machine tool?) with scraped ways not linear bearings....like all design, it depends on what the machine is called upon to do

Linear bearings don't have to sit on scraped surfaces. They will perform well enough even on milled surfaces though ground would be better.

If greater accuracy is desired for their mounting (or for creation of any precision surface), there are methods involving poured confections that also work as an alternative to scraping. The issue will be wear, so even though you see machines with Turcite ways, there are disadvantages. OTOH, the Kitamura video looks like he is scraping a column mounting point, so wear issues would be minimal to use the technology there, just as it would to mount linear guide rails.

For really heavy hogging, the box ways are still unequaled by linear bearings. However, most of the lower end of the market has gone to linear bearings, which tells you where the lower costs lie.

It's interesting just how much technology and effort has been expended to help overcome the limitations. High Speed Machining in some sense is all about making lighter machines with linear ways perform at material removal rates more similar to the old school hogging counterparts. For the most part, the battle was won, though the religious arguments still rage, and there is a scale where the linears still can't compete.

Not clear the high end jig borers of old have much on CNC of today. It's one reason they're not very prevalent any more.

Cheers,

BW

grf
12-30-2009, 04:03 PM
i am not trying to open another "war", never said it is not a good technique (i am in new in this field in total). i am truly surprised that this technique is still here and from what i see even in mass produced machines. usually most things now days change for the sake of change. i understood the significance of the process but if you saw to someone(without knowledge) the video and you say this is very expensive and precise machine they would look at you strange. people would expect lasers and other fancy stuff.

i think i should stop before the tread gets out of topic because of me.
thank you all for your input to my questions.

ps
Happy new year to everybody

Mcgyver
12-30-2009, 06:58 PM
....that's the opportunity and challenge of the internet, so much content but how to tell whats credible? its the old "If you say with enough authority it will be believed"....even if you've never ground or scraped a bloody thing.

a war? naw, I refuse in engage in a battle of wits with an unarmed man :D


i understood the significance of the process but if you saw to someone(without knowledge) the video and you say this is very expensive and precise machine they would look at you strange. people would expect lasers and other fancy stuff.

as you say, without knowledge, not to one who knows machines. Scraping is expensive, very time consuming and don't mean to imply its being done everywhere...its probably rare overall because it take so much labour (that's scraping, not frosting which is quick an does not add to accuracy). I don't think in terms of whether a technique is good or bad, or champion one or the other like its a sports team. The goal should be knowledge, understanding each techniques merits and drawbacks and when a particular technique might be the best to use. Mind you my filter is whats applicable to lighter sized industrial stuff, i pretend no expertise on larger production stuff.

Mcgyver
08-16-2010, 05:40 PM
I can offer cast iron lapping plates for your requirement.


STOP SPAMMING EVERY thread that mentions surface plates or scraping with your CRAP.

:mad:

is there someone watching who can ban this guy, he's just spamming his ads into threads. Of course i'm sure its top quality stuff :rolleyes:

rowbare
08-17-2010, 09:42 AM
STOP SPAMMING EVERY thread that mentions surface plates or scraping with your CRAP.

:mad:

is there someone watching who can ban this guy, he's just spamming his ads into threads. Of course i'm sure its top quality stuff :rolleyes:

There is a read and white triangle icon in the header for each post. You can use that to report spams and inappropriate posts.

bob

Mcgyver
08-17-2010, 12:53 PM
thanks, these commerical guys should get a room, I mean buy an ad....feel free to delete these post of mine as well and i'll use the triangle from now on

Capone0017
09-15-2010, 07:02 AM
thanks, these commerical guys should get a room, I mean buy an ad....feel free to delete these post of mine as well and i'll use the triangle from now on



You're telling someone else to buy an ad when you have "McGyver's Workshop Copyright 2009" watermarked into the photos you've posted?

rowbare
09-15-2010, 08:30 AM
You're telling someone else to buy an ad when you have "McGyver's Workshop Copyright 2009" watermarked into the photos you've posted?
Let's see now, you have 4 posts, McGyver has 1100+. I think that buys him a bit of slack. And to set the record straight, only two of over a dozen images McGyver posted to this thread were watermarked.

I am not a big fan of obtrusive watermarks on images, but sometimes that is what gets posted. :violin: In the grander scheme of things, it's no big deal.

bob

Chris D
09-16-2010, 06:34 PM
I may have already posted about this topic before, probably in a different thread about the same subject - lapping ways.

I cannot believe this missinformation is still being spread by these people. No one in the machine tool industry laps ways - you simply do not do that! Yes, it can make ways look "pretty", smoother, more shiny, whatever. It does nothing, absolutly nothing to improve accuracy of the machine!

Lapping is an indiscriminate process and the way these people promote it with lapping a saddle to the bed is even more insane! If you had a qualified straight surface to begin with, you might be able to improve flatness a bit, but even with a qualified flat surface, it is still hit or miss.

I build machine tools for a living. Really expensive, very accurate machine tools. The last one I built was an OD grinder. It uses linear ways (profile bearing ways). The Z axis length of the machine is 3 meters - over that 3 meter distance I have the rails straight within 12 microns (vertical and horizontal deviation measured with a laser). You do not achieve that sort of accuracy by using a hap-hazard process such as lapping an entire surface!

The base for this particular machine tool was machined in MI by a company that knows how to machine a base for straightness and flatness. Interestingly, this is the first time I have ever seen rail mounting surfaces milled rather than ground. More interesting is the accuracy achieved. The locating surfaces were more than 3 times more accurate than any base we have had ground!

So, please take my advice (advice from a guy who actually builds industrial machine tools), do not lap your ways. Yes, they may look pretty, but other than that you probably did more damage than good.

Don't always expect grinding to be more accurate than machining, I too was very surprised by the accuracy of milling on that particular machine base.

Chris

Cruiser
09-22-2010, 11:36 AM
Lapping of any slide way is only for one reason and one reason only !
It is to reduce friction !
Many of the low cost machines from Asia are coming in with machining tool marks left on the slides and doves which when put face to face and made to slide have an extremely high coefficient of friction. To make it a mating surface we have lapped them with a compound so that the surfaces were of a bearing quality and would hold an oil film and bringing the coefficient of friction down to a level which is acceptable. The trick is to use a motion which is even over the extent of the job and knowing when to quit. The end result is very similar to a scraped or ground finish, which the home or small shop people can't obtain. It is not intended to increase precision in any way or accuracy but just make it usable. Putting a two machined surfaces together, of cast iron or any material, would require a very long breakin period and may be too much for the drive to accomplish. Also, it is akin to a phonographic finish used in valve seal faces in order to cut one finish into another finish for the purpose of creating a high pressure seal

BobWarfield
09-22-2010, 11:46 AM
Cruiser is right, and it can improve the accuracy of the machine because it allows you to run the gibs more tightly.

Chris D, we're not talking about lapping a machine hand scraped to precision. We're talking about machines usually just milled and sometimes that not very well. The amount of lapping involved is not sufficient to remove enough material to reduce the accuracy, but it is sufficient to allow the ways to run more smoothly and hence to let you adjust the gibs tighter, which results in more accuracy.

Such are the compromises on these cheap machines. Yeah, it's horrifying to "professional machine tool builders." But in the end, go with what works.

Cheers,

BW

MrWild
09-22-2010, 02:03 PM
I disagree. Lapping ways by sliding the saddle back and forth induces more wear to the middle of the traveled portion than the out side areas. This depression ends up causing a looser fit in the middle and tightness at the ends. Premature wear is the result of lapping. Hand scraping is HARD. it takes real effort on top of craftsman diligence at checking and rechecking progress. I don't have the strength for it. Being disabled I chose a different method of bringing the ways on my X2 to a better finish than the raw machined surfaces it came with. I used a knife profile second cut mill file.

The smooth flat surface of a second cut mill file lets you lay it across the entire surface for a full engagement. The knife edged profile allows the file to get right into the root of the dove tail so you can scrape/file the entire surface. Indiscriminant filing will cause worse damage to your ways than using lapping compound, so you don't go crazy and just file away. You want to check the surface just like you would when hand scraping. I like that an 8" double cut knife edge mill has a little flex to it. You can lay it flat, raise the handle just a little bit, then use your other hand to apply downward pressure as you slide the file. Because of this slight flexibility you can address problem high spot areas without over filing a lower area. Yes, it takes craftsmanship to file in the right areas, constant checking to find those areas, and knowing when to stop, but it is more precise than lapping, and easier on my disabled hands than scraping. My X2 is very smooth across it's entire range of motion now with no tightness anywhere with properly adjusted gibs.

If I could, I'd hand scrape. I can't so I precision filed. Seeing the surfaces after lapping turns me off to the entire process of way lapping.

BobWarfield
09-22-2010, 02:15 PM
I disagree. Lapping ways by sliding the saddle back and forth induces more wear to the middle of the traveled portion than the out side areas. This depression ends up causing a looser fit in the middle and tightness at the ends. Premature wear is the result of lapping.

How do you know?

That certainly wasn't my experience, Cruiser's, or that of a lot of others who've lapped their ways.

If you're doing it right, you're not going to add enough wear to do anything but smooth the rough travel of the gibs and ways.

I would definitely lap before I'd take a file to the ways.

Sincerely,

BW

Cruiser
09-22-2010, 02:41 PM
Using WEAR as an argument is down right ridiculous. If you take a pair of machined surfaces and slide them to each other repeatedly then you have wear till the surfaces mate, and by mate I mean that the highs are abraded off till the surfaces average out and the surface area of contact increases to that of the equivalent which has been ground true. Even the scraped surfaces do the very same thing, the highs reduce till the surface area in contact bears the load and wear reduces to a minimum and longevity is seen as a benefit. Wear will be the highs when fresh surfaces are in friction. As the surfaces mate and the surface area averages in, the wear reduces to a minimum constant with the exception of contaminants abrading between the surfaces.
Lapping in of surfaces if done with long strokes will accelerate the wear of the highs till they flatten out. this is why lapping is so common and easy. this is why lapped in valves are so common with engine heads, It mates the two surfaces to each other to eliminate irregularities and bring them into the same plane.
any machine that is ground or hand lapped is going to be better than the low end units indead, NO ARGUMENT. But, a rookie Scraped machine or even a rookie ground machine would most probably be CRAP. The same holds true with lapping, but, lapping will be easier and much less technical to achieve a useable machine. And as with anything, If done correctly, it works.
Wear is not only a destructive element but also a tool to achieve perfection.

Chris D
09-22-2010, 07:35 PM
Perhaps I demand a bit more than the average guy - I am a machine tool builder by trade. I have been involved with CNC machine tools and conventional machine tools for over 3 decades. I worked as a tool maker, an applications engineer, service engineer and everything in between. I worked for Japanese machine tool builders, German machine tool builders, and Swiss machine tool builders.

I can say without question, no where in the world would a machine tool builder "Lap in the ways" of any machine tool. You will continue to believe what you think is 'right' and I will never change that. However, I will continue to communicate that it is wrong, that there is no justification for it, and if anyone cares to prove me wrong, show me a real machine tool builder that "laps their ways in" to either reduce friction or improve accuracy!

This is NOT an "old school" versus "New school" concept. If the "machine tool" is junk to start with, lapping the ways is not going to improve it or make it a "quality machine tool". If you think you are "reducing friction", okay, but if the damn thing has so much friction to begin with, it has more problems than lapping is going to cure.

Those that believe they are doing something good by lapping ways will always believe in what they believe. Those of us who have worked with machine tool over the years, rebuilt machine tools, serviced them, and built them, know the reality - lapping is nonsense and advocated by people who do not have the knowledge or experience to be voicing an educated opinion one way or the other!

Chris

grf
09-22-2010, 08:03 PM
i am no expert( not even experienced)

i do understand both points of view.
personally i would never lap the ways of my mill as i find it very uncontrollable process for my liking.
i understand why in theory it is wrong and why the proper tools are not laped but there are people out there that do not have proper machines and lapping improved their cheap machines. they never said that they transformed them to a Bridgeport or something but if someones machine was loosing steps and after lapping it stopped and the parts that he builds do not have tolerance problems compared to before lapping it is hard to argue.
if a machine has machining marks of .5mm that the surfaces grab to and you can feel they do not move maybe lapping makes the sharp edges smoother and tables start moving reasonably then why not. even if it creates an inaccuracy of .3mm on a machine that did not work at all it is an improvement.
at another thread i asked why dovetails or box ways and not linear bearings. to me i would not scrap or lap or do anything like that. if i wanted a real improvement for my mill i would trust skf or another proper company to give me the tools to do so. but that is me a not experienced machinist that does not know how to do one or the other.

at the end imo if you want a proper machine you find a way to save money for it.
if you cannot then you start compromising. a compromise is connected to every persons priorities-finances-needs-abilities-believes-likes-etc.
if you have the money you pay a tool maker to fix your cheap machine. if you do not you start looking at other options.
lapping is just one of them to do what you want.

it is highly unlikely to go around the world on bare foot but if you cannot afford flying on foot will get you two steps closer to the target.
cheers from down under

Cruiser
09-22-2010, 08:06 PM
Chris
When I put together my shop I did not have large money to buy the best of the best. I had to make do, as do many others. As for term of service, I have been around machinery all my life. All manner of machines including wrenching on F100 jet fighters in Viet Nam, and 30 yrs running a multitude of machines as a machinist. When it comes to top dollar machines, I agree with you whole heartedly. But, We are dealing with the Chinese who don't necessarily know what QC stands for or take Pride in what they do. If I had found the things I've found with my machine in a high dollar machine I'd be making some lawyer very rich from the legal matters.
When it comes down to being able to take a piece of crap and turn it into a silk purse, Well, that is what I do best.

MrWild
09-22-2010, 11:12 PM
A knife edged mill file is not going to break the bank. How about two word pictures. Looking at the front of the X2, lets admit that there are peaks and valleys running right to left on the Y axis saddle dove tail bearing surfaces. Pushing the saddle front and back while lapping takes some material off the peak, but the mating surface has a valley eroded to match the eroded peak. The valleys allow the mating surface to come down until there is full contact across the surface. It isn't flat, it's just kind of mated more or less.

Now look at the same surface from the side and note the stroke. More surface slides past the middle of the base, than the front and back surfaces see. Unless you are sliding the saddle right off the base, and keeping that saddle perfectly level, the front and back portions of the base will NEVER be level with the middle. Does it matter? Only if you are a craftsman. if you are just a hobbyist plunking around and playing, no, it will work just fine. For me, it's knowing it isn't as perfect as I can make it with my abilities. If your craftsmanship level of ability is smearing on a paste and stroking the saddle back and forth, hey it seems to work for a lot of people.

alex781
09-23-2010, 03:08 PM
This thread has left me with more questions than answers. I have an X2 mill which binds near the very end of the Y axis (at the handle end, before the saddle overhangs the base), no problems anywhere else and accuracy of the usable portion of the axis seems good. Whatever method I use I only want to remove metal from the 0.5" long trouble-spot, and it's clear that lapping will not do that.

I am trying to decide if it's worth attempting to scrape such a small area, or would I be better off just carefully filing or sanding it down. If I carry on as it is will it get worse? I am completely new to this so any advice is appreciated!

MrWild
09-23-2010, 09:31 PM
This problem could be caused by a bump. Not a bump in the part exactly, but bumping the part's way surface while everything was in pieces. The said bump might have raised a divot in that one area and the small imperfection causes a binding. A flat knife edged mill file is PERFECT for smoothing the divot down. A few strokes is all it probably needs. In fact, by lightly sliding the file on both right and left surfaces ALONG with the dove tail gib areas, you might even feel the roughness. (not all surfaces at the same time, but making sure you check/file all surfaces. Sometimes the problem isn't on the way, but the gib area.) You don't need to be aggressive to file it down, just some smooth strokes holding the file flat to the surface you want to bring into conformity. For your problem, I'd shy away from lapping the surfaces completely. You obviously don't want to wear more of the middle away.

alex781
09-27-2010, 02:46 PM
This problem could be caused by a bump. Not a bump in the part exactly, but bumping the part's way surface while everything was in pieces. The said bump might have raised a divot in that one area and the small imperfection causes a binding. A flat knife edged mill file is PERFECT for smoothing the divot down. A few strokes is all it probably needs. In fact, by lightly sliding the file on both right and left surfaces ALONG with the dove tail gib areas, you might even feel the roughness. (not all surfaces at the same time, but making sure you check/file all surfaces. Sometimes the problem isn't on the way, but the gib area.) You don't need to be aggressive to file it down, just some smooth strokes holding the file flat to the surface you want to bring into conformity. For your problem, I'd shy away from lapping the surfaces completely. You obviously don't want to wear more of the middle away.

Thanks for the tip. Can't feel a divot by hand but I do think filing will be the way to go, when I feel confident enough! Just need to work out which side or both needs filing.

Cruiser
09-27-2010, 09:15 PM
If one is going to file cast iron then there are a couple important things to do, one is to keep the file clean by brushing it every couple of strokes. two is get some white chalk and give the file a stroke with it to help keep the fine from loading in the files teeth. another is to never ever as in NEVER back drag the file as with any tool this will dull it in no time. Last is if the file is not new, hold it up with a strong light and see if light reflects from the cutting edge of the teeth of the file. If you don't know what i'm saying then take a known used abused file and try it ! A dull file is useless.
lastly, when filing insure there is no oil or grease on the base being filed. some carb and choke spray will degrease it pretty good.
one fine point is when done take a bit of leather and some moly lube and rub it into the degreased iron, don't leave residue but insure it is well stained with the moly. then oil and slide away.

MrWild
09-30-2010, 02:30 AM
Something I learned fast when I was a machinist trainee, was that just touching the surface left hand oils on the steel and the file would have a much different cut until the oil was either cleaned off, or cut away. I could actually feel the file slide across the surface instead of cutting it. This is with a new sharp file too. Any oils do make a difference in how a file will cut. Good point to bring up Cruiser.

That Moly trick is one I plan on trying. I brought my tube of engine assembly lube (moly) in from the shop just so I can try out that embedded trick.

MrWild
09-30-2010, 02:36 AM
Something I learned fast when I was a machinist trainee, was that just touching the surface left hand oils on the steel and the file would have a much different cut until the oil was either cleaned off, or cut away. I could actually feel the file slide across the surface instead of cutting it. This is with a new sharp file too. Any oils do make a difference in how a file will cut. Good point to bring up Cruiser.

That Moly trick is one I plan on trying. I brought my tube of engine assembly lube (moly) in from the shop just so I can try out that embedded trick.

Mcgyver
10-09-2010, 01:07 AM
Let's see now, you have 4 posts, McGyver has 1100+. I think that buys him a bit of slack. And to set the record straight, only two of over a dozen images McGyver posted to this thread were watermarked.

I am not a big fan of obtrusive watermarks on images, but sometimes that is what gets posted. :violin: In the grander scheme of things, it's no big deal.

bob

thanks Bob, the watermark was mainly put there to stop people from stealing the images or using them without permission. They, like anything else you or I create is copyright so is was a reminder to those who should know better

Capone, geez, all I can say is piss off. There is nothing commercial about those photos or my activities here. What value have you added?

Chris D, you guys wondering what to do, listen to Chris... .stunning to see advocates of a wrong and flawed process (lapping to machine tool parts) argue the point to one who's profession it is to properly create bearing surfaces. One is free to do whatever they wish in the privacy of their own shop, but when a beginners are promoting a quite destructive process, it should be noted. Its about as sound a practice as dumping abrasive in your crankcase to reduce engine friction.

If lapping ways is presented at a site more machining focused such as Practical Machinist or the Home Shop BBs .....there will be no debate or ambiguity in the responses.


Using WEAR as an argument is down right ridiculous. If you take a pair of machined surfaces and slide them to each other repeatedly then you have wear till the surfaces mate, and by mate I mean that the highs are abraded off till the surfaces average out and the surface area of contact increases to that of the equivalent which has been ground true. Even the scraped surfaces do the very same thing, the highs reduce till the surface area in contact bears the load and wear reduces to a minimum and longevity is seen as a benefit.

Hogwash. Wear is precisely the problem....because you're not lapping with a charged lap as a cutting tool, you are randomly wearing away at two mating pieces by stuffing abrasive between them; not really lapping in the accepted sense. The results will not be even and will not create a flat surfaces. you can end up with curves or even a roller coaster where bearing surface is reduced. Nor will it maintain parallelism or squareness. Scraping ways isn't willy - nilly, its a methodical process where small bits of material are taken of exactly where they are suppose to be take off to not only get the right bearing percentage, but the way also flat, square and parallel to the other elements as required.

Its not imo a matter of spending big bucks on a machine, a cheap Chinese mill can be made as good or maybe better than the best new mill out there using the right techniques. Toil and tears lets the poor man have the best mill. Here's a el cheapo mill table i recently scraped - things are within a tenth or two all over; I don't know that you could buy a better one...of course some would respond they don't need one this good. Fine, but scraping can be be done to different levels and what is for sure is that the indiscriminate use of abrasives in the bearing surfaces will create a machine with more slop and less accuracy; a worse off machine.

http://i785.photobucket.com/albums/yy132/michael01000/scraping/photo247-large.jpg

Your comment about QC struck a chord. On this mini mill x/y, they had carefully ground to a nice finish one of the surfaces adjacent to a way surfaces in an attempt I'm sure to overcome their current reputations...problem was it was the wrong surface! in the pic below the ground surface bears on nothing - the incredibly rough surface i've just started to scrape is the bearing surface. too funny

http://i785.photobucket.com/albums/yy132/michael01000/scraping/photo316-large.jpg

This picks are part of write up I'm working on describing how to scrape in these mills. So many inexperienced guys as witnessed here advocate lapping that I thought rather than just whining about it I'd try to create some tools so they could do the job properly.....after its done there'll be no more excuses! :D

BobWarfield
10-09-2010, 02:23 PM
ROFL, McGyver certainly does have a lot of posts, he’s a copyright law expert, a scraping expert, a critic on most fronts, and I am sure a legend in his own mind. His work is so fantastic I know I personally lie in bed awake until late at night scheming how to steal his photos but my evil plans are foiled by diabolical watermarks. Drat! Getting back to the real issue and point of the thread, :rolleyes:

Everyone is arguing about completely different things so of course they don't agree.

ChrisD's post is excellent, and should be read carefully by all concerned. He is mostly right, and frames exactly why the group's discussion is really about two completely different things:

- "I am a machine tool builder by trade"

Is everyone here also a machine tool builder? Well you're not, are you? Chris is, some others are, but most of those experts are not hanging around CNCZone wondering how to get their Asian mini-mill to perform better by scraping it in to a ten thousandth. They have skills, facilities, and budgets that are radically different than yours. If you have access to all that, you will get a better result too. If that doesn’t work for you, you need another plan.

Remember that there are all kinds of other things the builders can make the same argument for. They laugh at mills with 1600 rpm spindles, mills that use steppers instead of servos, mills without toolchangers or enclosures, and control software that can’t take feedback from a servo encoder into account just to name a few. The professionals live in a different world and are solving different problems. They are not trying to build CNC machines for a few thousand dollars. As I said, you need another plan because a lot of what you are going to be doing the Experts will shake their heads at.

We are not reconditioning machines that were once scraped to perfection by Hardinge. These machines have never seen a scraper, though they may have been scratched up by some other random piece of metal. Most have not been ground either. The ways are rough milled. The question is with limited skills and resouces, how do we make them "good enough?". Or perhaps not even that, "How do we make them better?"

- "If you think you are "reducing friction", okay, but if the damn thing has so much friction to begin with, it has more problems than lapping is going to cure."

Yes, absolutely, you are so right! These little imports do have a lot of problems, more than lapping will cure if we are honest. The average machine builder or professional machinist will throw up their hands, shake their heads, and ask why you are wasting your time on this junk! You can’t make these imports perform as well as a Mori Seiki by lapping the ways, nor by scraping either BTW. We are in violent agreement! But you can get a CNC mill that cuts to a thou or better very reliably. Not nearly as efficiently and quickly as a pro machine, but you don't care, because you're a hobbyist.

Here is the bottom line:

If you want to think like the professional, you wouldn't consider either lapping or scrapping. You wouldn't be fooling with these little imports. You'd buy a real machine, and likely one that is already running-- those same pros are also not dropping everything to learn how to scrape. There are pages of professionals posting about this, and you can go read that advice now if you like. Head over to PM and ask what they think about retrofitting a nice Bridgeport knee mill. Better, save the embarrassment and search—it’s been asked many times. They're going to tell you to forget about repairing or retrofitting. Plenty of CNC machines that still work great are for sale cheap in this economy. Go buy one and get on with your business.

If you’re not a professional, you are a hobbyist. It's all fine and well to have delusions of grandeur about scraping in your machine to a ten thousandth just like McGyver. Excellent! Maybe you are restoring some venerable old Monarch 10EE. Cool! If you've got the time and skill, go for it. But if you don't, you're going to need another plan. You are in search of shortcuts because you aren’t going to spend the time or money a professional would, and if you could you don’t have their skills. Get over it, there is no shame in that. You can still build a CNC machine accurate to a thousandth.

As for lapping, understand why we are lapping before you decide it can’t possibly work. It’s not about making anything straighter or crookeder whatsoever as Cruiser and I have both said. You don't do enough of it to “wear out” the straightness if you're doing it right. You're making 20 to 40 strokes with each grit and that's it. Experts should look up exactly how much material can be removed by abrasives with 20 to 40 strokes (hint, using machines, diamond grit, and optimal conditions you get 0.000029"/minute removal). You will find that the effect is not capable of moving a thousandth, or in most cases more than a couple tenths. I think we agree these machines were not accurate to tenths to start with?

Understand clearly why we lap and what the lapping process can and can’t do. Not all machines need it. Many don’t: no need to lap indiscriminately. But understand that if you're talking about an RF-45 of a vintage where the ways are really rough and you want to run the gibs very tight, then I will paraphrase Chris and suggest that you consider doing what someone who has the knowledge and experience of having done it has done. Lapping works. It is an improvement. If done properly, it does not destroy the accuracy of your machine, quite the opposite, it improves it.

In that case lapping is simply the moral equivalent of scrapers flaking just for better oil control and behavior. That’s all. If you’re a scraper, snowflake instead. It’s prettier and probably works better. Otherwise, look at it this way:

Lapping the ways takes a couple hours of an afternoon. If you succeed, your machine is better for it. If you fail, you spent 2 hours and now you need to scrape it in like the Experts suggest. That’s going to take a lot more than 2 hours, so what have you really lost? It’s probably taken longer than 2 hours to write all the posts in this silly thread. You will not suddenly make your machine more inaccurate if you don’t get crazy with too many strokes. The abrasive just can’t remove enough material for that to happen.

BTW, even if I wanted "professional results" on an RF-45, I wouldn't bother with the scraping. I would take the disassembled machine, fill all the cavities with epoxy granite, haul it to a machine shop, mill off the dovetails and put a precision guide surface, and then I'd mount a set of linear rails to it.

Scraping isn't the be all and end all either, but I'm sure that will ignite yet another controversy!

(nuts)

Cheers,

BW

Cruiser
10-09-2010, 02:57 PM
For the last several years now the IH mills have been GROUND and the lapping in process was for the previous mills which were straight off the mills, and showed it. The lapping in was more of a process of improving the surface finish and knocking off of high spots.
The new ground IH mills are much better than the older mills in many ways and even have added iron in the column for the doves to keep them from flexing.

Mcgyver
10-11-2010, 09:55 AM
ROFL, McGyver certainly does have a lot of posts, he’s a copyright law expert, a scraping expert, a critic on most fronts, and I am sure a legend in his own mind.

If it seems that way, well that's the difference between us....generally I try to only blabber forth on items where I'm experienced and knowledgeable and ask questions where I'm not. It is actually a striking difference in our approaches. Questions instead of statements until ignorance abates. Strange that that keeps you up at night though, were I in your shoes I'd have a a different set of priorities.

alex781
10-11-2010, 10:27 AM
I am going to apply a quick fix (light filing as described) in the meantime just to get things moving and because it can be improved on later.
But I hope to read the write up on the mini mill, it looks like a superb job to me!

BobWarfield
10-11-2010, 02:25 PM
If it seems that way, well that's the difference between us....generally I try to only blabber forth on items where I'm experienced and knowledgeable and ask questions where I'm not. It is actually a striking difference in our approaches. Questions instead of statements until ignorance abates. Strange that that keeps you up at night though, were I in your shoes I'd have a a different set of priorities.

McGyver, there are about 40,000 unique visitors a month to CNCCookbook, along with several thousand machinists using G-Wizard from 500 different manufacturing and machine shops. I correspond with a great many of them and have learned a lot from them. Many are associated with the tooling or machine manufacturers. These are not shy people about reminding me any time I fail to ask the right questions or get the right answers. But, like so many machinists, they are also very generous with their time and knowledge--it's a great crowd to deal with, for the most part.

For example, I called up Aaron Moss who developed this process of lapping the ways to solve a particular problem and asked him a great many questions before I undertook the process myself. I also did the research to see exactly how much material might be removed and considered just how much damage it might do if the job was totally botched. I then tried it on one IH mill and have a second without lapped ways so I'm pretty familiar with what the before and after look like.

Now of course you have a wealth of experience with RF-45 mills and way lapping or you never would have commented, at least by your own description of your style.

Yes, I am delighted to say there is a big difference between our approaches.

Sincerely,

BW

terminator
04-25-2011, 02:40 PM
HI EVERYONE.
I HAVE BEEN TRYING TO GET HOLD OF 1.2mm TURCITE B SLIDEWAY FOR 2 MONTH'S
NOW AND AM LOSING HOPE. IS THERE ANYONE WHO CAN HELP ME OUT WITH A SMALL
AMOUNT OR KNOW WHO WILL DEFFINATELY BE ABLE TO SUPPLY IT?
REGARDS
DANIEL
SOUTH AFRICA

Cruiser
04-26-2011, 12:13 AM
The exact slide way you ask for is probably going to be only available from the original manufacturer and financing is NOT available.
However, if you confine your search to turcite you will find many suppliers with it in stock. It comes in strips and you will need at least one. It is then cut to fit the recess or pocket, of your slide way and bonded in. I don't remember if it came in different thicknesses but should and I believe the glue is also available. You may be able to find it in your country, but might have to shop around.

DavidJSwanson
08-02-2011, 03:44 PM
This picks are part of write up I'm working on describing how to scrape in these mills. So many inexperienced guys as witnessed here advocate lapping that I thought rather than just whining about it I'd try to create some tools so they could do the job properly.....after its done there'll be no more excuses! :D

Were you still working on a writeup? I'm sure some of us are interested, even if we haven't posted about it.

spoiledbrat
08-08-2011, 11:40 AM
Indeed! We all want to see that writeup! I have a 10 x 54 import mill that would simply love this treatment. That is, once I practice my technique on the straightedge, and any thing else I see that needs to be flat. :D

Cheers,

Rob

Mcgyver
08-12-2011, 07:44 PM
Indeed! We all want to see that writeup! I have a 10 x 54 import mill that would simply love this treatment. That is, once I practice my technique on the straightedge, and any thing else I see that needs to be flat. :D

Cheers,

Rob

that's a man sized project! The scraping of the mini mill x/y you see above is covered in great detail in a series currently appearing in the Home Shop Machinist on scraping. It started with March/April '11 issue and will run for quite a while (no doubt to the delight of some and chagrin of others....its long but its what it took to cover it). Its fairly exhuastive, from basic equipment, techniques, making a scraper, making a rotary lap to keep it sharp and a hose of projects

I thought scraping the mini mill would be an excellent inclusion as its gives a bite sized example of scraping dovetails and also since there are so many out there, it gives everyone the resources to get them running like Swiss watches. This thread was partially a catalyst for that particular project. For the guys who realize there's no free lunch, either pay big bucks or roll up the sleeves, it hopefully brings understanding to how bearing surfaces are aligned and shows the way to fixing them properly.

thanks for the encouragement & interest!

LUCKY13
08-13-2011, 09:57 AM
I just seen the Turcite B somewhere in strips with different thicknesses and lenths ( they also had the glue). I cant rememeber where it was but if I find it I will post back. I think doing the search like someone already meantioned with google will find it for you. It is available if you look. ALso I think they call it Moglice or something like that is also out there.


JUst a thought, when glueing on metal of any kind using something like paint thinner to clean the surface real good should be done on used parts. Lacor thinner I think works best. Oils, grease will inbed in metal and it takes some work to get it out. SOmething as simple as Dawn dishwashing soap can help to get it clean first. Even something like a finger print on the metal can cause problems so use the thinnner last and use it right before doing the job.


Jess

skullworks
08-13-2011, 04:01 PM
that's a man sized project! The scraping of the mini mill x/y you see above is covered in great detail in a series currently appearing in the Home Shop Machinist on scraping. It started with March/April '11 issue and will run for quite a while (no doubt to the delight of some and chagrin of others....its long but its what it took to cover it). Its fairly exhuastive, from basic equipment, techniques, making a scraper, making a rotary lap to keep it sharp and a hose of projects

I thought scraping the mini mill would be an excellent inclusion as its gives a bite sized example of scraping dovetails and also since there are so many out there, it gives everyone the resources to get them running like Swiss watches. This thread was partially a catalyst for that particular project. For the guys who realize there's no free lunch, either pay big bucks or roll up the sleeves, it hopefully brings understanding to how bearing surfaces are aligned and shows the way to fixing them properly.

thanks for the encouragement & interest!

Could you post contact info to order those back issues as well as getting a current subscription?

Mcgyver
08-13-2011, 11:32 PM
Could you post contact info to order those back issues as well as getting a current subscription?

here you go :)

http://www.homeshopmachinist.net/home?noredirect=true&noredirect=true

skullworks
08-15-2011, 10:37 AM
Sweet! Thanks!

spoiledbrat
08-16-2011, 08:09 AM
Am I correct to think that in order to true up a 54" mill table, I would require at least a 54" straight edge?

I have found raw castings on machinerepair.com. I have yet to find any other provider of raw castings, especially in the length I require.

I have done a little pattern-making, and live near an excellent foundry. If it comes down to it, I will make my own pattern, and maybe sell a few cast iron blanks on ebay. I have never made anything on that shape before, but I can talk to the resident pattern-maker there to nail down the risers/auxiliary stuff required to get a good casting.

Either way, looks like I will be needing a larger surface plate than I thought.

Rob

whitewittock
07-15-2012, 10:04 AM
Sorry to revive a dead thread, just wanted to post my X2 mill workaround for a badly machined way:
1) Find an alu strip of the correct width and jbweld it on to the troublesome way.

While it is hardening:
2) slide the saddle to and fro a few times so that the alu side is parrallel to the good side.

You need a thinner gib once the strip is attached, and you may need repeat step 2 a few times after the jbweld sets (without any grit) but you can easily get it so wiggling of the saddle is impossible over the entire travel.

Mcgyver
07-28-2012, 11:03 AM
Were you still working on a writeup? I'm sure some of us are interested, even if we haven't posted about it.

Hi David, because of the recent post, I was reminding of this thread....the write up has been running as part of a long series in Home Shop Machinist on scraping. Part 8 is the current issue and begins detailed coverage of dovetail scraping - the x/y table shown in post 123 is the subject of dovetail part and the last major project of the series. The series began from the ground up; basic, making scrapers, sharpening them, techniques, controlling geometry etc.