# Lathe Bed Restoration



## earthbound

Hello folks, 
I've found a lot of good information on this forum so I though't I'd pick the brains of the experienced machinists here about restoring the bed of my lathe.  I have an Atlas 12 inch lathe, and like many who own one, it's seen better days.  I've done a lot of work on the thing (and had a blast doing so) and I'm having trying to weigh my options with refinishing the bed.  For those of you who aren't familiar with the Atlas lathes, they have flat ways instead of the inverted v ways and this seems like a simple enough thing to fix up.  Would it be worth having a machine shop surface grind these?  Or heck, maybe even fly cut the ways and I'll take a stab at scraping them after?  Is scraping then flaking something very hard to do?  I've never tried to scrape metal but I've been working with wooodworking hand tools for about a decade and a half now and I have a decent touch with this sort of thing.  I realize I'd need access to a master surface of an appropriate size.  Has anyone ever reconditioned an Atlas lathe bed that turned out really good?  Thanks for the input!

Drew


----------



## Bob Korves

First, welcome to the forum.  

Please define how worn out it really is.  Report back with real numbers.  If you want to find out how to do that, and how to do scraping, read Machine Tool Reconditioning:
http://www.hobby-machinist.com/threads/connelly-on-machine-tool-reconditioning.41802/
it is a free download in our files section, around 500 pages or around $100 to buy in hardcover.  Restoring a lathe by scraping is in no way a trivial project.  Just learning to scrape well enough and understanding how to rework the geometry of the lathe so you can start the project will take considerable time and effort.  I am not trying to scare you off, scraping is a great way to get excellent results in restoring a lathe.  It might take at least 100 hours for a competent scraper hand to do the job, probably way more for a beginner.  If you try to cut corners the project will never come out correctly and will probably be sold disassembled, from what I have often seen.

The flat ways do not make the job much easier, and the other surfaces of the lathe should be made flat, parallel, and square, with the proper geometry, as well.  Intuition will lead you down the wrong paths.

Typical machine shops cannot handle grinding lathe beds.  It takes a large grinder, in excellent condition, and a skilled machinist who has done lots of that work.  Few shops will touch it, and it is expensive.  Milling is not accurate enough, and considerable scraping would still be required afterwards.
Again, not trying to scare you off, just a reality check.  The only quick and easy way to get a reconditioned lathe is to buy one in nice shape and then sell (or keep) what you have now.

Well worn lathes do lots of very nice work.  That is why I asked for numbers on how bad it really is.  Machinists make accurate parts, the lathe is just a tool.


----------



## MozamPete

My thoughts, and I'm no expert but I also have a lathe with flat ways (Myford ML7) which could use a little work so I have been giving it some thought with a view to a mid life spruce up of my 57 year old lathe.

While the top horizontal surfaces of the ways are the most obvious and visible, they are the least important.  Any wear here will cause the tool to rise and fall which would result in only a fraction of the wear's difference in the diameter of the work being turned.
Any wear on the vertical guide surface however will cause the tool to move towards and away from the work resulting in a change in diameter equal to twice the wear.

As an example (in the extreme to demonstrate):
For wear on the vertical guide surfaces of the ways:
D2 = D1 + (2 x Tool Horizontal Movement)  i.e. if the original diameter is 25mm and the tool moves 1mm back then the new diameter is 27mm

For the same wear on top horizontal surface of the ways:
D2 = Sqrt( D1^2 + (2 x Tool Vertical Movement)^2)  i.e. if the original diameter is 25mm and the tool moves 1mm down then the new diameter is 25.08mm

So my thought is to concentrate on the vertical surfaces of the ways.  This wear also causes my problem that when the saddle gib is adjusted to be nice and firm at the chuck end of the bed it binds up as you move to the tailstock end, so you end up adjusting it for the unworn tailstock end and living with it being looser than ideal at the chuck end.  To fix this I need to remove some material from the width of the way at the tailstock end to bring it in line with the narrowest (most worn) area's width.

I'm not familiar with the Atlas, but when the Myford was manufactured all four vertical surfaces of the ways were machined, however on mine only two are used for guiding the saddle (only the front way).  The two inner vertical surface are used for guiding the tailstock.  So the back surface of the back way is untouched and a virgin reference surface. Some lathes are 'wide guide' (including the later model ML7s) and use the two outer ways to guide the saddle so it would be one of the inner vertical way surfaces that was the best reference surface.

Figure out what is your least worn surface and measure everything with reference to that surface to determine how much material you would need to remove to bring then all back to straight and parallel.  I have mic'ed mine and I would need to take a maximum of 0.05mm off each side of the front way.

In my case I'm considering following a method I have read about where a jig is made up to run on the reference surface and grind the worn vertical surfaces back to parallel - I'm not looking for perfect, but it should be able to make an improvement (and there is no way I can justify spending the sort of money it would take for a professional regrind).  Still in the pondering stage so not fully committed to this idea yet.


----------



## 4GSR

Drew,

There's bound to be grinding shops in the Chicago area that can surface grind the top of the ways for you.  And probable touch up the sides too, without getting too carried away.  There's a couple of machinery rebuilders west of you in Rockford, but I doubt they would touch it without you paying the price of a new lathe.
I guess the question is, how much are you willing to spend on reconditioning your lathe?
If the wear is minimal, less than .005", scraping the bed might be the way to go.  You will need a fairly large surface plate and or straight edge to start the project off.


----------



## earthbound

Gents, I measured a .008 dip on the ways...  That seems like a lot in my novice opinion. I have to measure the difference in the width of the ways. I can see how that gib riding on the outer vertical surface can act like a taper attachment. Ive found myself offsetting my tailstock frequently mid project depending on how far I am from the headstock.


----------



## MozamPete

Myford used to say more than 0.005" variation in way thickness or 0.003" in way width was time for a regrind - back when the used to offer a factory regrind service.



From the Myford guide "_Pre-owned Lathes - A Guide to Inspecting before you Buy_", Sept 2010.


----------



## earthbound

Looks like I may contact a shop to grind it and then I'll try scraping it myself. Obviously id practice scraping something like a steel plate first. Has anyone ever made a home made straight edge? Is it dumb to try to scrape a face of an I-beam with a master reference surface? It seems like that's all a camelback edge really is. An iron or steel face with a structural spine.


----------



## Kernbigo

There is no point of scraping it after it was ground, that is good enough, don't even flake it just something to collect direct. Scraping is a art if you don't know how don't even attempt it on something like that . I did machine repair for 25 years and plenty of scraping, on thread grinders. In order to make a straight edge you have to use cast iron steel is to un stable, it will change from the heat of your hand when you  are scraping it in to a granite block.


----------



## MozamPete

Was just going to say the same thing - if you get it professionally ground you wouldn't need to scrape the bed.  I doubt it would of been when originally manufactured. 

You may need to scrape the saddle to make good contact with the newly ground bed - but ideally you would get the contact surfaces of the saddle reground at the same time so you shouldn't need much scraping.


----------



## Kernbigo

As far as the saddle goes it can be milled, and after that turcite can be applied, just keep track of the stock removal


----------



## MozamPete

Kernbigo said:


> As far as the saddle goes it can be milled, and after that turcite can be applied



If you're only taking 0.008" off the bed I wouldn't think there was any need to build the saddle up again with Trucite (at least there wouldn't be on my lathe).  The half nuts should be able to handle the small misalignment with the leadscrew.  I understand it can be more sensitive if you have a power feed on the cross-slide.
Or were you just proposing trucite as an alternative to grinding/scrapping?


----------



## Kernbigo

The way it works you grind the bed and mill the saddle and only turcite  the saddle. You never turcite both surfaces


----------



## 4GSR

If you have determined that the bed has worn around .008", that usually means the saddle wear can be 2 to 4 times or more, in wear than the bed.  That being said, you may have to take off close to .016" to .020" of material off of the saddle for near 100% cleanup.  So to make up for that, you will need a material thickness of about .025"-.030" thick, not including glue, to add in to bring it up to standard.  Then you still have to scrape in the new material, Turcite or equivalent, to get the proper bearing you need.


----------



## george wilson

Actually,it is the REAR vertical surface of the bed that guides the carriage along. And it is that surface which becomes worn the most over time. In fact,there is no reason why the front edge would get worn since the carriage is pushed AWAY from it under cutting pressure. A machinist modified his Myford lathe so that the carriage also used the inside of the FRONT flat way. He finally convinced Myford of the superiority of his plan,and they adopted it. It should not really have taken much convincing,as anyone with common sense would have seen the advantage at once. More likely,the modification added cost to the making of the lathe. But,fortunately,it made use of the existing parts with just an extra bit of machining and an extra gib.

As to the Atlas lathe bed: I'd remove AS LITTLE metal as possible since the bed is already TOO THIN. Scraping ONLY,no machining should be done. Grinding should only remove just enough to do the job. Getting a machine shop to remove only just enough is the neat trick here! If it were mine,I'd not trust them,and would scrape. But,that takes equipment you might not have,of course: a precision straight edge,and the scraping tools.

Lastly,you'd be SURPRISED at how little material taken off the bed will cause the half nuts to rattle along the leadscrew! You'll have to shim it lower on both ends.


----------



## MozamPete

George, it was the other way around at Myford - the earlier ML7s  and Super 7s (pre 1972) were narrow guide and only used the two vertical shears of the front way to guide the carriage, they then changed to wide guide using the two outside shears (i.e. the front shear of the front way and the back shear of the back way).

The earlier design is the top section below, and post 1972 they changes to the lower section.



One justification for the change I have seen is as the carriage is 'U' shaped the front and back offer longer bearing surfaces and hence less pressure/wear than using inside of the front shear.  If fact on my ML7 (one of the earlier narrow guide style) I found it was the middle 'finger' on the carriage that had suffered the most wear and was causing the cross slide travel to not be perpendicular the lathe axis (hence my facing off was convex - http://www.hobby-machinist.com/threads/cross-slide-facing-adjustment.44572/)




I have seen articles about people changing both ways -  modifying a worn out older lathe to wide guide basically as an alternative to regrinding the worn front way, and modifying a *brand new* later model (post 1972)  lathe back to narrow guide as the owner considered it a superior arrangement.


----------



## martik777

Have you considered planing the bed? I am not familiar with the Atlas bed but possibly you could use the unworn inside vertical sections of the bed as a reference and build a sled to slide on these surfaces.

I recently planed my south bend v-way bed using a sled made with the tailstock base, sliding on the relatively unworn tailstock v-way with excellent results. I only did the front v-way since that was where most of the wear was. 

The whole operation took maybe 20 mins, after the sled was fabricated. With the flat ways you could get by without the compound on the sled. Stone or lightly file after the planing to debur and scrape in some 1/2 moons to complete.

Here's a video of the process (not mine):


----------



## 4GSR

martik777 said:


> Have you considered planing the bed? ..........


This only works if you have non-worn surfaces to work from.  I did this on my Lodge & Shipley when I rebuilt it. I had surfaces or datums that had not seen any wear and were not bearing surfaces to re-grind the ways by as well as replan the ways the tailstock rode on, too.


----------



## MozamPete

How exactly does the plane blade look? Are you cutting the full width of the way with each pass or is it a number of narrower overlapping passes?


----------



## Kernbigo

it has to be like a Rockford planer each pass is the width of the cutting tool


----------



## martik777

I made this as a prototype but ended up using it for the job. The angle of the compound was setup with an indicator to match the v-way angle.  I set the depth of cut to the full depth of the wear, approx .005. and made 20 or so passes to cover the width of the ways.  If you watch that video, you will see him turning the compound dial a few thou after each pass.


----------



## 4GSR

Kernbigo said:


> it has to be like a Rockford planer each pass is the width of the cutting tool


Not necessarily. 
 That's ideal if you have a real planer to mount the bed down to and plane.  Small cuts about .025 to .030" per pass is sufficient.  Depth of cut just enough to get 100% cleanup.  This may require making several passes to do.  The problem doing this method is, you have to come back and scrape out most of the tool marks and establish your bearing points per square inch.  This is where a scraped cast iron straight edge comes in handy.  The straight edge does on have to be the length of the bed for this method.  Just long enough to make good impressions and pay attention to the markings so you don't loose coplanarity of the surfaces involved.


----------



## tq60

That Atlas is not worth "real money" or time required to do what has been discussed but the top can look ugly and can be cleaned up relatively cheaply by stepping outside the usual places.

The lathe is about the same size as an auto engine head.

So check arround for engine machine shops as there are still some arround that have surface grinders for truing heads.

After locating some take the bed only to them and discuss your needs so they are clear to only remove enough material to have a consistent surface and also that the surface is parallel to the bottom end to end.

Have you checked this yourself to insure the bed is not bent?

Check thickness of bed and it should match your wear indication but if same thickness end to end the bad could be warped.


Sent from my SAMSUNG-SGH-I337Z using Tapatalk


----------



## kdtop

martik777 said:


> Have you considered planing the bed? I am not familiar with the Atlas bed but possibly you could use the unworn inside vertical sections of the bed as a reference and build a sled to slide on these surfaces.
> 
> I recently planed my south bend v-way bed using a sled made with the tailstock base, sliding on the relatively unworn tailstock v-way with excellent results. I only did the front v-way since that was where most of the wear was.
> 
> The whole operation took maybe 20 mins, after the sled was fabricated. With the flat ways you could get by without the compound on the sled. Stone or lightly file after the planing to debur and scrape in some 1/2 moons to complete.
> 
> Here's a video of the process (not mine):



I have been thinking more about your sled option.  I can't see for sure, but is your sled riding on a dovetail below the plane of that top surface?  In my situation (see crude diagram posted before), I have inner tailstock ways, and outer carriage ways.   So I can't plane down the entire surface flat because part of that surface would be supporting the sled.

But perhaps I could leave the inner ways at original height (preserving the support for the sled), and just use a planing action like you show to drop the outer ways down to a consistent depth -- say 0.010".  This would accentuate the step that is already there, but should be fine.

KT


----------



## martik777

Sorry I missed your diagram and post #10 from: https://www.hobby-machinist.com/threads/repair-worn-1930s-craftsman-atlas-ways.91748/

My sled is riding on the a flat portion that is slightly lower than the tops of the 2 outer carriage V-ways *and on* an inner v-way that is the same height. I think you only need to plane the top ways "C" as the other parts, B and A will have very minimal wear. You can check this with a straight edge or with a dial indicator attached to your sled.
I used a brazed carbide toolbit but HSS should work too.  The whole process took less than an hour including a little hand scrapping to clean the ways up. I didn't bother building up the saddle since I did not have any engagement issues.


----------



## kdtop

Quick update of progress so far.

I decided to try to grind the ways myself.  I have been taking a machining class at the local community college, and they have a surface grinder.  The bed travel was less than the length of the ways, but we thought we could get full reach with 2 set ups, doing about half each time.  And I planned to scrape in the final product. So if there was a slight mismatch between the two runs, I could correct with scraping.  They have a large surface plate that would hold the ~40" length of the ways.  

Of course it didn't go as planned...  

The overall ways have a bottom contact surface on each end, each about 10 inches long, where the feet are normally bolted on.  These were ground flat first, with the top working surfaces being placed downward, in good contact with the magnetic chuck.  After that, the unit was flipped to start work on the top ways themselves.  But approximately the middle third of the bottom surface didn't have any contact the magnetic chuck.  Imagine a bridge with a support on each side and an arch over the river.  The height of that arch was only about 1/8" so it didn't really trigger me to realize the problem initially. But it was enough of a gap to prevent good fixture and work holding.  The grinder was a large DoAll brand, and it has the feature of coolant.  But the class apparently thinks high-flow coolant splashing is too messy and doesn't have it enabled or working.  And instead I was instructed to spray water from hand-held bottle.  The grinding took 2 days, and it was only on the 2nd day that I was told about the spray bottle.  As you might imagine, this ended up not being a good solution.  With the heat of the grinding, the middle, gapped section ended up raising up through heat-warping, and was excessively ground.  If I had a table stroke length equal to the full length of the ways, I would have noticed it grinding more in the middle. But because I was doing it half and half, with the ends of each half being approximately in the middle, it was impossible to detect this initially.  End result is that with later inspection on a surface table, the center was about 15 thousandth's low!

On the advice of the class teacher, my next plan is to take the ways to a local machine shop which has a Blanchard horizontal rotary surface grinder.   He thinks that the cost won't be excessive.  We'll see.  If it is, perhaps this will be the impetus to buy that better lathe!

In retrospect, I am sure experienced machinists here could have told me that this wasn't going to work.  I am counting this to part of my education.  Let's just hope my lesson isn't too expensive.  

I'll post progress as I go along.

KT


----------



## Weldingrod1

Blanchard will be pretty rough relative to normal surface grinding.

Sent from my SM-G892A using Tapatalk


----------

