Lathe way rebuilding

"SRF" snipped-for-privacy@hotmail.com

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That's typical for an older lathe. Some drop of the ways there is not going to make a lot of practical difference to what the lathe will make for you. As part of setting up, try turning the ends of a piece of stock (say twelve inches long) between centers (using a faceplate and lathe dog rather than a chuck). Use a dumbell-shaped piece, and compare the diameters turned at each end (in the same pass, with the same bit setting). This will give a preliminary idea of how much of a taper the lathe is turning.

Use the lathe for a while to see what it will produce for you before you get serious about some re-machining.

One possible workaround is to set up with a steady rest to turn fussy pieces out to the right of the worn area, where the ways are better.

Strip material to re-align bed ways is available, although with any method you are looking at having to re-do a number of surfaces (such as the carriage bottom vees), not just the bed ways. They all need to be re-aligned together. That's one reason a fix (such as plating) of the ways alone won't be good enough.

Frank Morrison

This topic comes up frequently. The short answer is, there are various techniques that are proposed for re-working small lathe beds. And yes, a 10L really does qualify as a small machine. The larger ones often have removeable, replaceable beds or bed ways.

One can machine and re-scrape the existing ways. Or one can use the 'good' portions on either side of the wear to guide a grinder that re-works the rest of the bed.

But the inevitable fact is that one can purchase a nearly new entire lathe, for the cost of having a worn bed re-scraped. I've never heard of anyone who tried to plate up the worn areas, but I think that would be even more expensive in the long run, than simply rescraping the entire bed surface.

Jim

================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ==================================================

No, it's more like a stub morse #5. Even that is off slightly, but it's pretty close.

Well, that may only be a few thousandths. If the wear on the front and back way are similar, it really makes little difference in the accuracy of the machine. If only the front way is worn, then the saddle will tilt, and that can make the diameter error worse. $6000 sounds quite a bit high. How about just grinding it, and doing the scraping yourself? You'll learn a lot, and it may not be a big job to scrape it after the grinding cleans it up to almost perfect.

One question, though. Is it a hardened bed? That is a real bear to "scrape", as I have found out the hard way! I have been working over a Sheldon 15" lathe with a hard bed, and chromed cross slide. The bed was a total bear because it is so big, but the cross slide is almost worse, as it is incredibly hard!

I have some real doubts that would work real well. Home plating, you mean the thing with a couple of AA batteries and a brush? That applies metal by the nanometer. If you tried to plate up .003" of wear, you might not be able to complete the repair in this century! You'd probably need to apply the Nickel or Chrome immersed in a bath, with a current of amperes, for a week to build up .003" of wear. (This .003" is just a wild guess of the wear as you describe it.)

Flame spraying of hard Chrome or some similar material could build up the low spots, then you'd probably build up the entire bed with a thin layer of the hard facing. Then, it is ground smooth and straight, and generally not touched up any after that.

But, if grinding the whole bed is going to be needed, you might as well just do that, only, and be done with it! As far as I know, you can't flame spray a bedway without having to grind it smooth afterwards.

Jon

Is it South Bend's own taper?

I think it is the infamous No. 4-1/2 Morse taper. That was used to get a taper that did not have excess length hanging out the front of spindles with a nominal 1-3/8" I.D. Those are the spindles that are large enough to accept a 5C collet body.

Many lathes (South Bend, Logan, Sheldon, Clausing, etc.) with 1-3/8" I.D. spindles came with a hardened and ground MT 4-1/2 to MT 3 or MT 2 adapter so that commonly used MT 2 and 3 cutters and tooling MT could be used in either the headstock or tailstock.

To make a adapter, steal the angle from inside the spindle with a dial indicator mounted on the compound, turn it between centers from the preferred metal, then mount it in the spindle and drill and bore or ream the desired inside taper. Make match marks on the adapter and spindle nose for indexing it. If you can get it hardened and ground it would be good but an unhardened one will provide good service for the average HSM shop.

A bed regrind should hold a tolerance of 1/2 thousandth over the length of the bed. That finishes the bed. Then you need to apply turcite or moglice under the saddle and tailstock which is then worked (machined and/or scraped) to the original factory height so components will align such as the lead screw.

Universal Grinding here in Dallas regrinds small lathe beds for less than a $1,000.

Gary Repesh

But that does not include the cost to re-fit the saddle and tailstock, right? I suspect that 1K will net you a re-finished bed, only.

Then one has to consider shipping costs. Unless the bed can be hand delivered to the shop, it rapidly becomes more economical to simply purchase a better, small lathe.

Jim

================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ==================================================

Sorry, wrong on at least two counts.

Neither Logan nor South Bend used a Morse Taper on their lathes with

Logan and South Bend both used proprietary tapers, the Logan

South Bend used (mostly) 0.602"/foot taper.

I can't say what was used on Sheldon or Clausing.

Thanks.

If I could find a local place that would do a lathe bed for six hundred, it would start to look attractive. I would have considered re-working my old, clapped out 10L, rather than buy a new one.

But the economics still don't quite work:

Cost of original 10L machine: $800 Cost to re-work bed of same: 600

Total, $1400.

I found a nice newer 10L with a flame hard bed, for $1800. Those economics work better:

Buy new machine for: $1800 Sell older machine: 800

Total, $1000.

And in the end I would have a ww2 vintage machine, with all the attendant wear in the rest of the bits, with only a single tumbler gearbox - granted it would have pristine, soft ways.

By spending four hundred *less* I would up with a newer machine, double tumber gearbox, and flame hard ways, also pristine.

This is one reason why small lathe beds rarely get re-done.

Jim

================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ==================================================

============== Jim, I give you an A for good sense, but a C- for your analysis. Still, it might work to use this technique on the Other Half...

You failed to include the cost of the original machine in your cost of the new machine. It should be:

Cost of original 10L machine: $800 Cost to re-work bed of same: 600

Total investment, $1400 for a reworked machine.

Newer 10L with a flame hard bed, for $1800.

Cost of original 10L machine: $800 Buy new machine for: $1800 Sell older machine: 800

Total investment, $1800 for a newer machine.

Which is $400 MORE, not less... ;-)

But, that $400 still probably yields better value than reworking the old machine when you consider all the other stuff you'd need to do in addition to simply reworking the bed.

Kevin Develop Windows(tm) Applications - in COBOL!

Heh. Funny how that works. Once the machine is in the basement for a few years, ms. Mulligan maybe forgets about the cost.

Jim

================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ==================================================

Thanks for correcting me. Maybe it was because all those adapters looked a lot alike?

I never had a South Bend or Logan but I know the Standard-Modern and Sheldon that I owned both had them.

Sheldon used a MT-4 on my 11x44 Lathe. I have the MT-4 to MT-2 converter - useful for spindle work with spur or with center, face plate and a dog.

Martin

Can't speak to other Clausing models but the Clausing 5900 series lathes have 4-1/2 MT tapers inside the spindles.