What came first, the chicken or the egg?

I have a bearing who's bore is .8735. That's smaller than a .875 shaft that it's suppose to fit over. So which is manufactured to fit which? The shaft to fit the bearing, or the bearing to fit the shaft?


In other words:
I have to design a shaft that will have a sleeve bearing fit over it. If the manufacture of the bearing says its bore is 1.50", do I have to machine the shaft to fit the bearing, or is the bearing oversized just a tad? How does that work?

One of the mods' hot buttons is making topic titles that have some relationship to your question. See all the unlocked threads for examples. Be ready to repost your valid question after this thread gets locked.

Steve

My apologies, and thanks for the heads up.

Mechanic Bill said:

I have a bearing who's bore is .8735. That's smaller than a .875 shaft that it's suppose to fit over. So which is manufactured to fit which? The shaft to fit the bearing, or the bearing to fit the shaft?


In other words:
I have to design a shaft that will have a sleeve bearing fit over it. If the manufacture of the bearing says its bore is 1.50", do I have to machine the shaft to fit the bearing, or is the bearing oversized just a tad? How does that work?

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You does what you got's to does to pick parts and dictate machining processes and dimensions to make the little f**kers JUST FIT most often.

All ears if you've got an alternate plan for self-adapting ones that will obey wish-fors or verbal orders?

I can cuss in about five languages, but not one, nor any combination of them have ever made a damn to an illiterate bearing fit, yet. Stubborn critters, not a lick of ambition. They are what they are.

Speaking of "illiterate"?

Just which part of the maker's spec was hard to read? The nominal dimensions? Or the tolerance they claimed?

You DID sit the course as to running fits for speeds, loads, and lubricants, too, yah? ME113 at WVU, 1963.

Machinery's Handbook helps if you skipped it. Then TEST your one, please. I don't have a great deal of confidence it is going to come good, first go.

No fear. If a "Designer" got that sort of goods right, first-go?

(S)he'd have to settle for dirtier hands and Machinist wages.

Can't have that, can we?

Designers and Engineers get too close to moving machinery, they'll bust it or injure theirselves.

Back to the drawing board, yah?

Didn’t realise it mattered, if you have one you make the other if you have none you make both, I tend towards fitting shafts in holes but have done the other.
Mark

There's a thing called bearing fit. I believe it varies on material and usage.

plastikdreams said:

There's a thing called bearing fit. I believe it varies on material and usage.

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and if you actually take the time to read deeply, this is a complex subject. plastikdreams hit it on the head. talk to bearing folk. read your machinist handbook, some slide on, some press on, some shafts must be cold shrunk or bearing heat expanded. for any application there is an optimal size for shaft and bearing, and an optimal tolerance for each. if its a sleeve bearing, final ID clearance is important too. it has much less to do with what you've asked about the fit, and much more about the application. briggs and stratton rotor tiller part or 60000 rpm grinding head?

Me thinks you would be best served over here:
The Hobby-Machinist Forum

Once again, why would you send someone to Nelson's shit hole?

How many chickens do you have?

Simple. You adapt the cheaper part, the replacement part. Like screws in a complicated housing. Ream sleeve

tdmidget said:

Once again, why would you send someone to Nelson's shit hole?

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Because...once again, it's better suited to them.

They won't get all butt hurt when their posts get locked over here,
if they would post over there.

It's a much better "fit".

I don't have any chickens, and I'm not going to get all "Butt hurt" from the likes of the minority who have nothing better to do than to try to pick on the those out of their league but trying to learn a thing or two from some professionals. I can tune you out as easily as I can wipe my ass.

And to those of you who DID help- thank you very much.

Closed due to meaningless topic title