[Mcgyver]

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]

Thanks again Mcgyver,

I ordered the Connelly book this morning.

[DieGuy]

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.

[mxtras]

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]

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]

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



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



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



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 )





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



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.



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!



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



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

[DieGuy]

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-...QQcmdZViewItem

[MikeAber]

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]

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]

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]

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]

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]

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]

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]

[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]

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]

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.