Way lapping, Scraping, Gib adjustment and Lock screws - Page 7


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Thread: Way lapping, Scraping, Gib adjustment and Lock screws

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    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.



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    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.



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    Quote Originally Posted by rowbare View Post
    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. 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.



    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



    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!

    Last edited by Mcgyver; 10-09-2010 at 11:40 AM.


  4. #124
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    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,

    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!



    Cheers,

    BW

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    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.

    Don
    IH v-3 early model owner


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    Quote Originally Posted by BobWarfield View Post
    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.



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    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!



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    Quote Originally Posted by Mcgyver View Post
    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

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    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



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    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.

    Don
    IH v-3 early model owner


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    Quote Originally Posted by Mcgyver View Post
    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!
    Were you still working on a writeup? I'm sure some of us are interested, even if we haven't posted about it.



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    Default writeup

    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.

    Cheers,

    Rob



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    Quote Originally Posted by spoiledbrat View Post
    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.

    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!



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    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



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    Quote Originally Posted by Mcgyver View Post
    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?



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    Quote Originally Posted by skullworks View Post
    Could you post contact info to order those back issues as well as getting a current subscription?
    here you go

    http://www.homeshopmachinist.net/hom...oredirect=true



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    Sweet! Thanks!



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    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



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    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.



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    Quote Originally Posted by DavidJSwanson View Post
    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.



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