Way lapping, Scraping, Gib adjustment and Lock screws

[MIKE JEFFERS]

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]

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]

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]

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]

WOW! I missed a lot while I was out! I feel left out....

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]

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 . 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]

Originally Posted by MikeAber 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

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]

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]

It's been interesting.

[MikeAber]

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]

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]

Geez, copyright 1954? By now someone should be able to just scan and upload that book I would think!

-niko