Bearing race nomenclature

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Bill Shields
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Re: Bearing race nomenclature

Post by Bill Shields »

This may sound totally off the wall...but what you are looking to do is 10 minutes worth of work for a cnc lathe once setup.

Even at $100 / hour machine time you may be better off to bite the bullet than go through the aggravation and $ to try to make what may turn out to be marginal at best.

If that is not an option...work from the assumption that it is or at one time was a standard bearing. From a real world standpoint I cannot imagine a jack manufacturer designing a jack that would require manufacturing a non standard bearing for such a mundane use. -> it is easier and more cost effective to design around an off the shelf component than go through the expense of making a custom bearing.

Have you considered that it may be a METRIC bearing? You say 1.1" -> could well be a 28mm bearing

Another option is to make a plain bearing out of bronze or whatever and grease the heck out of it
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Patio
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Re: Bearing race nomenclature

Post by Patio »

My .02 worth. If your round piece of tooling is held in the holder, angled creating a clearance under both the cutting face and the end face, as you mentioned. Then one would only need to put a flat grind on the top of the tool that has a little bit of back rake from center line of the material, This will create an elliptical form tool. Whether the race has an elliptical or round form will not matter to the bearing. If necessary one could take a cut, rotate the tool and take another cut, as long as the second cut is less than the tangent of the first cut. I would also think that, having the two radius's as close as practical to each other creates better support.
I think the main thing to remember is this is a floor jack's casters. The main goal it to support the load and secondary is to make it's movement easy to handle. The design to hold the load has been done by the original engineer. The better the finish and the truer the diameters the better it will handle, but this is a floor jack! If it is like most I have seen, it is pretty much and open bearing system, that get full of grease and crude, but it works. I also think if this was done with a carbide burr in a mill, using a rotary table it would work, but that is not what we do. :)
With that said, if you can do this in the lathe, I think you will be able to get the best finish and I think it is doable.
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BadDog
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Re: Bearing race nomenclature

Post by BadDog »

Bill:
Thanks.

The jack was made in the late 40s to somewhere in the mid 50s. The second version likely took the same bearing and was made until (I think) the early 60s. It's definitely standard, not metric. And definitely doesn't exist in any form I could find, including metric options. And that included calling around to all the local bearing houses that I could find, including those not so local shown as "locations" by the big bearing suppliers. Not sure how hard they tried, but they did produce some "closest" options the got back, and I would suppose all total had to be a few days worth of hours by more than a dozen potential sources. I even got some of the "you need to call your local representative locations" companies to put in effort (no idea how dilligent) to no avail. Called some motorcycle stem bearing specialties, including those that offer "conversion" ball races. But given the physical limits of castings, stack up, etc, it's just not something that I could find an option that would work. Also looked at taper, but the stack is too tall, and not enough meat in frame or caster to adapt. None were close enough to fit with the minimal stock for modification. And apparently, for rated weight, nothing is close to the small package provide by a ball bearing race. I REALLY didn't want to machine a race, but it's the most practical option I could find.

And yes, CNC would make this a LOT easier. I even know local hobby folks with CNC that might give me a decent deal. But if it's going to be made, I would like to figure out how to make it using my machines. That's why I have them. It may not work out, and has been abject failure so far, we'll see.

As for plain bearing, I've explored that option too. I was pretty close to pulling the trigger on UHMWPE, but decided to tackle the race in 17-4. I may go back yet.
Russ
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BadDog
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Re: Bearing race nomenclature

Post by BadDog »

Patio:
Thanks.

I like the ideas for a better way to handle that top profile (end of rod). That may be my next path of attack. I've also got a 1/4" carbide ball EM and rotary table, and that may also be my next attack, perhaps polished on lathe before (and after?) HT? I'll have to shake the eight-ball to figure out which. :lol:

I understand that it will create an elliptical profile due to the 5* tilt and flat top, and also with the quite similar aspect as presented even with the flat dished end. But for the reasons you talk about, I judged that acceptable. And I agree that it isn't highly critical, but part of my concern for engineering details is that my home solution won't ever be up to the standards of a commercial race in either hardness, profile, or finish. That's why I began to ponder the realities of load for non-load (primary) wheels and (approaching) "point" loads for the balls on a softer race, one that the OEM race showed signs of brinelling, but at the same time, fracturing into pieces.

I'm not sure about the simple profile and rotate using HSS on SS. It seems that work hardening would preclude such an approach. And my experience indicates that it's extremely prone to such things, though magnified by my less than ideal edge geometry failing rather rapidly.

And yes, it is an open ball system as typical for casters. Not super high precision, no seals, bad environment, etc.
Russ
Master Floor Sweeper
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