Needle bearings

Annealed M2 is around 220 - 240 Brinell. That's just convertible to Rockwell C, value of 20.

That's pretty soft steel, Don. Hot-rolled 1018 or 1020 is somewhere in the neighborhood of 130 Brinell. But cold-rolled is quite a bit harder.

Sure. I have more than a few that are decorated like that. And you can bend the shanks in a vise.

We seldom see real annealed HSS, because it takes a long temperature ramp-down from 1600 F to anneal it all the way. Like 24 hours or so. I don't know how close you can get with a quick heat-and-cool cycle; maybe it's not far off of the full-anneal value.

It's normally only sold in the annealed condition to the cutting tool manufacturers. I don't know how the twist drill companies do it after hardening the drill bits, nor just how soft they're able to get it.

But I do know, from my days as tooling editor at Machining Magazine, that those shanks are annealed, and that the steel is all in one piece, all of the same material. Or it was. They typically grind the shanks in a centerless grinder, and they're fed into a fixture, since they can't be through-fed. That limits the accuracy of the grinding.

I haven't been involved with these questions for 15 years, so, as with most things, I may be out of date. d8-)

I think I would have gone to real drill rod - center ground and HSS at least. I've bought some for an model engine I was building. Nicer finish and strength than making my own...

But the real part is best. Hate to have one blow up and weld on you or fall apart because of a hand made part not fitting at speed.

Mart> Thanks everyone! Found the Moog 508 at the local O'Reilly. Will pick up this am.

When I was 15 years old I owned an Indian 101 Scout. I don't remember what my father paid for it but it wasn't running when we bought it and was cheap. I worked on it for a year or more. I think it may have run (for moments) once or twice :-)

In retrospect I think it probably had a very weak magneto and I could have converted it to battery ignition easily. But alas, I was a very beginning mechanic in those days :-)

O.K. Pretty soft.

O.K.

Yes. Or turn the shank down to make a small Silver & Demming drill at need. :-)

Or -- perhaps the hardening is done by induction heating allowing the shank to remain soft.

Or -- perhaps retain the shank in the annealed state. It seems to me that the extra work of annealing the shank after the drill is hardened is an added expense.

O.K.

Still -- more information than I have.

But still -- my original advice to not use drill shanks as needle rollers stands. :-)

Enjoy, DoN.

I bought from these grinding companies.

This place has high quality center ground drill blanks. It comes annealed so it can be ground into real HSS drills. Quote:

"From start to finish 100% American made.

We specialize in high speed steel drill blanks of all sizes from .005" to 3.500" in diameter with a .0002 tolerance and lengths up to 60".

M-2 has a rockwell of 62-64.

M-42 has a rockwell of 65-67.

Drill Blanks are also known as core pins, punches, dowels, reamers, gages, mandrels, pinions, and guide pins.

All of the above can be produced from a variety of materials and hardnesses. "

This is where they sell them :

And have a more updated web. The high quality Labrobe (or such spelling) got theirs here - and may still do.

Mart> >

...

The suggested drill rod from McM-Carr is hardened tool steel and are solid rod full length...not _quite_ what a real case-hardened bearing roller would be probably, but will make a serviceable roller I have no doubt.

The M42 "ultra-hard" is Rockwell C66 per their datasheet...

Then those aren't annealed. Those are the fully hardened values.

I don't know. The standard heat treatment for HSS is pretty elaborate. It has to soak at high heat to get the carbides into solution. How in the heck they do that on drill bits, while producing a soft shank, I can hardly guess.

HSS is used by some custom knife makers, who heat treat it, and it's led to some confusion. You can harden HSS with a fairly simple heat-and-quench. But the result is not high-speed steel. It has no red hardness if you do it that way. It's full of carbides, but it goes limp at machining temperatures.

Maybe. Again, I don't know how it's done.

Absolutely. Even if you had fully hardened and precision-ground pieces os HSS, they likely would not make good bearings. It's not formulated for that service. Bearings are made mostly of AISI/SAE 52100 alloy for specific reasons, having to do with the way it behaves upon heat treatment. It's not simple to make a bearing or a race that will withstand many millions of cycles at high loads.

I know that. They come the way you want them. M2 when hardened is like that... I bought M2 and M42 for push rods and axles and the like. All soft enough to saw through. Information was provided on tempering if wanted.

Mart> >

A little more looking found from the AST bearings website the following...

"...The typical surface hardness for bearing components ... ranges from

60- 64 on the Rockwell hardness C scale (Rc)."

so from a hardness standpoint this material fits right in. They use

52100 chrome steel polished and all, of course, but again as a stop-gap solution as was the point of the original post the above would get by reasonably well...

It's not just hardness. It's the relationship of surface hardness to core hardness. If the core is too hard (and fully-hardened HSS is hard all the way through), heavy, repeated loads cause fatigue cracks in the interior, and evenual destruction by cracking. You've probably seen some cracked ball bearings, which are a little more vulnerable than rolloer or needle bearings.

Again, if a bearing isn't heavily loaded, the fatigue, "false fatigue," and spalling problems probably won't show up. If it is heavily loaded, and subjected to millions of cycles, as in a car's driveline, you need the right material.

SAE 52100 and some similar proprietary alloys are the right materials.

...[snip]...

I didn't claim it was perfect match...

I repeat...

"... as a stop-gap solution...the above would get by reasonably well..."

until either find the real replacement or similar long-term answer.

And as just one final addendum, I did look briefly when making the original posting; Mc-C has some chrome steel rod (not 51200, specifically) but nothing in the small diameters Ivan needed and as it appeared he was looking at a make-do anyway, the harder tool steels were all that seemed to show up...now if I thought there were any chance at all that this vehicle was being put together as a highway daily or long-distance driver, I'd not suggest it but I just really, really doubt that's the case...

As it turns out, the real part was available after all, so it all became moot point, anyhow.

Right, I saw that. I was just commenting on the properties of bearing steels, and that materials like music wire (typically special, 1.0

-1.2% plain carbon) and HSS aren't suitable for something like an automobile U-joint in the driveline.

It's a lot more complex than we discussed, but those principles apply when the loads are heavy and you expect a long life with a lot of cycles. It's not necessarily true for other types of bearings.

OTOH needle bearings made from stainless TIG rod have held up well on the casters I made for my off-pavement hydraulic lift platform, which doesn't have to move when loaded.

-jsw