24" X 1" Belt Grinder

[LMMasterMariner]

Quick question: -Anybody having problems overrevving ball bearings?

For instance, given the 12 000 rpm angle grinder and a 60 mm OD drive wheel,
the suggested 62200 2RS1 (with 17000 max rpm) would get up to 24 k rpm...

(A 43 mm OD drive wheel would keep the revs down, but still provide 60 mph belt speed)

Any risk and/ or damage assessments out there?

Just asking, and better safe than sorry...

Johan

Yes. You are right. Thanks for pointing this out.
It's better to put 3 bearings 6200 2Z (limiting speed 24000 rpm) than 2 bearings 62200 2RS1.
When I was ordering bearings, I ordered 6 pcs 62200 2 RS1 and 9 pcs 6200 2Z, but decided to keep these 6200 2Z for some other projects.
Will replace them once I come back home.

Cheers LMMasterMariner

[old_toolmaker]

Several years ago I had a high rpm air powered hand grinder. I had two of these totally blow apart where the ball bearings simply disintegrate. Pieces flew everywhere. I think it hade something to do with not having dry air. I should have had a better air lube system as well.

[DIYSwede]

OTOH: Given the 17000 max rpm of a 10 mm OD inner axle,
would perhaps allow the 30 mm outer race a max (theoretical) rpm of 25 500 rpm
(given an assumed ball cage max rpm of 8500 rpm)?

https://en.wikipedia.org/wiki/DN_Factor

I still remember my engineering teacher in 1977 dissing rotating outer races rather than inner axles.
BAD engineering practice...

Or, am I mistaken (again)?

Johan

[old_toolmaker]

Unless I am mistaken, I would think the outer race would rotate at would rotate at a slower speed than the inner race. But I am not an engineer.
I am still interested in what you find. Maybe the manufacturer could shed some light on this.

[DIYSwede]

No big deal - I was just bothering my brain with this.

Hypothesis: When an axle in an inner race rotate @ 17000 rpm,
hence the cage should rotate with half that rpm (as the outer race is fixed) 8500 rpm, Right?
This is where I was mistaken:
In wrongly assuming the outer race could turn faster than twice the given ball cage max speed.

Thanks for pitching in, you guys!
Johan

PS:"Nobody can fool me as effectively and easily as I can"

[mklotz]

...PS:"Nobody can fool me as effectively and easily as I can"

The first principle is that you must not fool yourself - and you are the easiest person to fool. - Richard Feynman

You're in good company. It's a darn hard thing to learn. DAMHIKT.