24" X 1" Belt Grinder

[LMMasterMariner]

Thanks for clarifying!
From my (too) quick glance at the drawings I thought the crowned wheel was on the top front position,
now I realize I was wrong, again!

I guess shoulda gone through your eminent drawings more carefully - not jumping to conclusions... Ah, well.

ATB
Johan

Thanks for the word 'eminent' when describing my drawings, which are all made by MS Paint. PhotoFiltre is used to rotate parts and gears are designed with GearDXF. Never had patience to start learning and using any CAD program.

Cheers
LMMasterMariner

[DIYSwede]

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

[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.

[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

[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.