Spinning bearings with air
- tornitore45
- Posts: 2077
- Joined: Tue Apr 18, 2006 12:24 am
- Location: USA Texas, Austin
Spinning bearings with air
The street wisdom is "never spin bearing with compressed air"
Why?
I suppose it may run the RPM way above specs, but that depends on the way one holds the nozzle respect the bearing.
Is easy enough to control the RPM to be wheel below spec while cleaning a bearing that feels gritty. Drown it in kerosene and spin it gently.
Why?
I suppose it may run the RPM way above specs, but that depends on the way one holds the nozzle respect the bearing.
Is easy enough to control the RPM to be wheel below spec while cleaning a bearing that feels gritty. Drown it in kerosene and spin it gently.
Mauro Gaetano
in Austin TX
in Austin TX
Re: Spinning bearings with air
For one thing, slide that ball bearing onto your finger and spin it up to about 10,000 rpm and have it seize.
You'll have an unpleasant experience!
You'll have an unpleasant experience!
Glenn
Operating machines is perfectly safe......until you forget how dangerous it really is!
Operating machines is perfectly safe......until you forget how dangerous it really is!
-
- Posts: 1852
- Joined: Tue Dec 06, 2016 4:05 pm
- Location: Elmwood, Wisconsin
Re: Spinning bearings with air
I think that the assumption is that you will spin it as fast as you can get it to go, dry.
- tornitore45
- Posts: 2077
- Joined: Tue Apr 18, 2006 12:24 am
- Location: USA Texas, Austin
Re: Spinning bearings with air
An how did you learned that, Glenn?For one thing, slide that ball bearing onto your finger and spin it up to about 10,000 rpm and have it seize.
One reason for always question rules. What may be true for a 4 ounces bearing may may not apply to a 10 grams or a 9 pound bearing (not likely to be be fingered)
Seem like the rule refer to playing rather then trying to accomplish something useful minding the limitation.
Mauro Gaetano
in Austin TX
in Austin TX
Re: Spinning bearings with air
In keeping with that, NEVER spin up a "fidget spinner" with air. The plastic hoops cannot hold the weights after a certain rpm. Disaster may ensue. My buddy tried it but fortunately he quit before anything happened.
I know no-one here would ever try this at home.
--earlgo
I know no-one here would ever try this at home.
--earlgo
Before you do anything, you must do something else first. - Washington's principle.
Re: Spinning bearings with air
I would guess that the reason is that you are blowing contamination into, and oil/grease out of, the bearing race, thereby shorting the life of a new bearing about to be installed. But yeah, cleaning an old gritty bearing I don't think its going to make any difference. After initial cleaning, multiple washes with clean solvent and then a good oil/regrease is probably better.tornitore45 wrote: ↑Sat Mar 09, 2019 2:16 pm The street wisdom is "never spin bearing with compressed air"
Why?
Re: Spinning bearings with air
The reason you are not supposed to spin bearings with air it two-fold. First: You have NO lubrication on a freshly cleaned bearing. High rpm with no lube spells short life of the bearing. Second: As said earlier, it's easy to exceed the rated speed of the bearing.
When cleaning and drying the bearing, it's ok to use air and spin the bearing at LOW rpm. Just don't let it whiz into outer space without lubrication.
Good Luck,
Terry
When cleaning and drying the bearing, it's ok to use air and spin the bearing at LOW rpm. Just don't let it whiz into outer space without lubrication.
Good Luck,
Terry
Re: Spinning bearings with air
Thought:
Spinning an unloaded bearing is different than spinning a loaded bearing.
Overspeed at zero load is far less likely to cause a problem, than with a load.
~RN
Spinning an unloaded bearing is different than spinning a loaded bearing.
Overspeed at zero load is far less likely to cause a problem, than with a load.
~RN
-
- Posts: 1852
- Joined: Tue Dec 06, 2016 4:05 pm
- Location: Elmwood, Wisconsin
Re: Spinning bearings with air
I'm not sure that's true. With no preload the balls and the outer race have some freedom to rattle and clatter in that turbulent air stream rather than roll smoothly.
Re: Spinning bearings with air
According to some of my old bearing manuals, spinning the bearings dry with compressed air will scratch the races and the bearing balls. I've always held on to the bearing and let the bearing rotate slowly while blowing out with air. Lubricate the baring with light oil afterwards so rust bunny's don't start appearing until ready for assembly or packing with grease. Remember, air will have some traces of moisture in it, this will kill a bearing real quick. Another thing you can do after cleaning is dip it in clean fresh Naphtha and let dry. KenS.
Ken
Re: Spinning bearings with
My aircraft mechanic friend is zealous about air and spinning a bearing. He claims that it doesn’t take much movement with a dry bearing to cause damage. After cleaning in solvent they will blow the bearing out but restrict any moment in the bearing. He said that is standard practice in the aircraft repair industry. He won’t even let me spin a bearing by hand unless it has been repacked with grease.
Re: Spinning bearings with air
Personally I think there's some sound logic behind not spinning up a dry bearing to high rpms. I've worked with multiple and highly experienced mill wrights and mechanics in the past who all seem to think it's a bad idea for various and multiple reasons that have already been mentioned. I've also craned in some extremely large bearings for mine site personnel and a few outside contractors. One thing in common with all of those crews is how gently each bearing is handled at every step even when weighing 200 - over 1,000 lbs. A bearings lubrication either grease or oil should provide a slight cushion between the hardened balls or rollers and the hardened race. I once saw a comment on a bearing manufacturers website, SKF maybe? that stated brinelling of the bearing internals can start on precision bearings with as little as 4 ft. lbs of shock load. Once a bearing is even slightly damaged they will start to fail early. Since so many think it's a bad idea, then being cautious and not doing so seems like the best practice to me since there's no benefits of running them up to a high rpm anyway. Blowing them clear of any solvent at low rpms and then immediately oiling or repacking I'm guessing shouldn't causes any problems.
Washing out and then air drying a bearing after a flush with Naptha/White Gas should be fine. However I learned the hard way that leaving parts submerged in it for up to a week is a real bad idea. I left an expensive 3 jaw soaking in it for about a week and found it covered in surface rust when I got back to it.
Washing out and then air drying a bearing after a flush with Naptha/White Gas should be fine. However I learned the hard way that leaving parts submerged in it for up to a week is a real bad idea. I left an expensive 3 jaw soaking in it for about a week and found it covered in surface rust when I got back to it.