Source for case hardened shaft?

[lazlo]

Does anyone know of a source for case hardened shaft in "nominal" sizes? I need a 5 - 6" section.

I want to install needle thrust bearings in the carriage handwheel on my Clausing lathe. I've purchased some drawn-cup needle bearings, and they need to run on a hardened shaft, but I need to be able to tap or thread the end for the handwheel screw.

I bought 1/2" Thomson linear shaft, which is case-hardened, and my strategy was to tap the center (which is soft) to attach the handwheel.
Unfortunately, Thomson shaft is spec'ed as -0.0005 - -0.001", so it's undersized for needle bearings.

Another possibility would be a drill blank, but I think those are through-hardened?

Any ideas?

[lane]

I for get the designation ,but you can get Thomson shaft in different class in terms of size one class is under one on and one over. . we used to buy it when ws were building machinery. call Thomson and ask.

[Fasttrack]

What about 4140 and then hardening it yourself after machining? (Or similiar material)

[Sparky_NY]

I believe the "drill blank" you mention is more commonly referred to as "drill rod". Drill rod comes in various steels, o-1, W1, A2, S7 and more. The rod is annealed as purchased and machines nicely. It is ground to size but unfortunately there is also a tolerance involved. (+-.001?) Its cheap also.

As for the alloy, W1 is water hardening but also distorts the most when hardened. o-1 is oil hardening and the easiest to work with. A light weight oil is used to quench it, vegetable oil from the kitchen works well, or mineral oil. It distorts far far less when hardened than W1. Do all the machining you need, then heat it until a magnet no longer sticks, then quench it, pretty easy.

Enco carries drill rod and very reasonably priced. I am building a gatling gun right now and drill rod is called out for many of the pieces.

[tattoomike68]

What about 4140 and then hardening it yourself after machining? (Or similiar material)

Or not, 4140 work hardens fine, the shaft he needs is short so it could be turned easy. I bet the original was 4140 or 8620 so you cant go wrong. -.0005 should be perfect for that job.

[SGW]

If by "drill blank" you mean a drill blank and not drill rod...it would in all probability be HSS and you'd never drill or tap it, or be able to anneal it. Drill rod is indeed a possibility, but you'd need to harden it, which would produce scale unless you got a shop to do it in an inert atmosphere.

Lane's probably got the best idea -- see if Thompson has some shaft that is different tolerance spec, that is suitable.

[John Stevenson]

Drawn cup bearings ?

Use the Thompson shafting and bore the bearing hole 0.001" undersize so it squeezes down.

Drawn cup bearings aren't that accurate anyway, certainly not to 0.0005"

.

[lazlo]

I believe the "drill blank" you mention is more commonly referred to as "drill rod".

I've got a bunch of drill rod which, like you say is annealed.
But I really mean drill blanks. You can buy drill blanks and reamer blanks from MSC, J&L, etc. I have a complete set of drill blanks in 1/64ths increments that I use for a Poor Man's plug gage.

Drill blanks are spec'ed slightly undersized (+0.0 - -0.0002"), and reamer blanks are spec'ed slightly oversized (+0.0 - +0.0002"). So a 1/2" drill blank would be perfect, but I'm pretty sure they're through-hardened?

Lane: "nominal" Thomson shaft would be perfect. I'll call McMaster in the morning and see if they carry it.

What about 4140 and then hardening it yourself after machining? (Or similiar material)

That's how a real machinist would do it My T&C grinder is in pieces waiting to be painted, and I think I would need to grind the shoulders where the needle bearings will ride after I harden the shaft.

I just bought some 17-4 shaft on Ebay -- that precipitation hardens at 900° (i.e., the cleaning cycle on the kitchen oven), and doesn't warp during PH, so that might be the easiest, non-grinding approach...

[lane]

Lazlo you can buy a harden bushing that is made to slip or press on a shaft to run needle bearings on . a good bearing supply house will have them are can get them. sheldon lathes use needle bearings on all the shafts and that is what they use on soft shafts for the bearings to run on. I know their is one are two good bearing supply houses in Austin.

[winchman]

McMaster-Carr has a selection of case hardened steel shafts. Just put "hardened shaft" into the search box.

Roger

[lazlo]

Drawn cup bearings ?

Use the Thompson shafting and bore the bearing hole 0.001" undersize so it squeezes down.

Thanks John -- we cross-posted

That's a great idea! When I first got the INA bearings, I thought they were defective since they were a very loose fit on a 1/2" plug gage. After several calls to INA tech support (in South Carolina -- their tech support is terrible), they told me that they're cut to size, but that the heat treat process widens the cup, and that driving into the correct OD hole will squeeze them back on-side.

I'd prefer not to bore the apron, but maybe I can make a thin sleeve to "shrink" the hole...