Worn lathe bed to be reground or planar milled?

[1silica]

I have a Litton brand table top lathe made for glassworking which has a handwheel operated tailstock that is driveshaft driven to be in sync with the headstock. Neither the bed or the tailstock ways are hardened. There is no oil lube system. The original factory ground finish on the bed was not scraped. I bought it used without being able to try it out. It turns out the tailstock sits about .060 lower than the headstock. I can't use it in this condition. It would cost me $15k to ship it to CA and have the factory refurbish it. I'm looking for less expensive alternatives. I found a local company that would planar mill the bed and the tailstock ways. Is this reasonable instead of regrinding? The planar mill finish is visually grooved and appears rougher than a ground surface. On the one hand this would hold lube better than a smooth ground finish. On the other hand given the roughness of both surfaces would they not wear much faster? Please share your opinions. This issue is way above my pay grade.

 

[Lo-Fi]

The question you've got to ask is this: is the tailstock height the fault of the bed or the tailstock? If it's constant down the length of the bed, it's probably not the bed. How did you take your measurements? Have you measured how parallel the taiksock spindle is with the headstock axis too?

 

[markba633csi]

I'm thinking someone swapped parts to make one lathe out of two- 0.060 is way more than the factory would have shipped (I think) and more wear than seems reasonable- but then maybe these things wear out quickly?
Probably it's going to be more practical to lower the headstock rather than raise the tail, but this gets into painstaking work regardless.
Are there any machine shops nearby that can advise you? A local shop may be much cheaper than 15K
-Mark

 

[Flyinfool]

Look closer at the areas where the tail stock actually makes contact with the bed. It almost looks like there may be some adjustability that is painted over.

If the tail stock is to low, machining it or the bed will only make it lower. You have something else out of whack. Are there any adjustments at the head to lower it?

 

[1silica]

Look closer at the areas where the tail stock actually makes contact with the bed. It almost looks like there may be some adjustability that is painted over.

If the tail stock is to low, machining it or the bed will only make it lower. You have something else out of whack. Are there any adjustments at the head to lower it?

There is no height adjustment for either stock. The set screws on the tailstock are to tighten up the single adjustable gib for front to back slop. Both stocks are the same casting. I've been told the factory first sets up the tailstock to run flat and parallel then grinds down the headstock to match. The final height above the bed is a nominal dimension and varies on every machine. Do you have any opinion about planar milling versus grinding?

 

[Flyinfool]

Grinding will almost always get a better finish than milling. This is why almost all machines and tooling are ground on critical surfaces. The very best stuff is scraped on critical surfaces.

 

[silence dogood]

Try contacting Litton Engineering Laboratories ph 1-800-821-8866.

 

[Rex Walters]

the tailstock sits about .060 lower than the headstock

I'm not at all familiar with such a machine, but I agree that there is no way 0.060" is from wear. If you remove the tailstock from the bed, does it look like there were wear strips that rode on the ways? Perhaps they are worn to nothing or missing entirely?

I do disagree with the comment that lowering the headstock would be easier than raising the tailstock, though. If the tailstock is consistently 0.060" low anywhere along the length of the bed (not easy to measure) I think my first thought would be epoxying some phenolic or turcite/rulon of the desired thickness onto the tailstock ways to raise it. The stuff is easy to scrape (or mill if you don't need too much accuracy) for final fitment and you wouldn't need a lot of it.

 

[projectnut]

I'm not sure grinding is what you need, but you might want to check with American Grinding & Machine Co. out of Chicago. They can advise you as to what would be the best course of action to bring the headstock and tailstock to the same level.

Welding and Fabrication - Chicago, Illinois - American Grinding and Machining Company

American Grinding and Machine Company Specializes in Grinding, Welding, and Fabrication Services.

www.americangrinding.com

They ground the bed and cross slide on my Sheldon MW-56-P back in 2001 when it was rebuilt by the previous owner. At that time they did a "dust grinding" which only removed .002". The cost at that time for a 56" bed and cross slide was $425.00.

 

[Shootymacshootface]

I'm not sure grinding is what you need, but you might want to check with American Grinding & Machine Co. out of Chicago. They can advise you as to what would be the best course of action to bring the headstock and tailstock to the same level.

Welding and Fabrication - Chicago, Illinois - American Grinding and Machining Company

American Grinding and Machine Company Specializes in Grinding, Welding, and Fabrication Services.

www.americangrinding.com

They ground the bed and cross slide on my Sheldon MW-56-P back in 2001 when it was rebuilt by the previous owner. At that time they did a "dust grinding" which only removed .002". The cost at that time for a 56" bed and cross slide was $425.00.

Wow, thanks for the link! I am considering having that done to the bed of my Heavy 10.
From what I have learned about tailstocks and bed wear, they always wear together, but the tailstock complicates things by the front wearing more than the back, so the quill dips down. On most popular lathes this can be addressed by regrinding and shimming the tailstock. It doesn't look like such and easy fix on yours , but there is always a way!