ah - now I get it

metalmagpie · Jun 23, 2020

I have seen michiganbuck post several times that you should start a spindle by turning it on and then right back off a few times before you let it come fully up to speed. That didn't quite resonate with me until I saw this:

Now I understand he must have come up in the plain bearing era. Makes sense to me now.

metalmagpie

michiganbuck · Jun 23, 2020

metalmagpie said:
I have seen michiganbuck post several times that you should start a spindle by turning it on and then right back off a few times before you let it come fully up to speed. That didn't quite resonate with me until I saw this:

Now I understand he must have come up in the plain bearing era. Makes sense to me now.

metalmagpie

likely this thread to get busted for poor title..

No. it is not just plain bearings, all bearings live better with a roll that comes from slower RPM , not a slide start..

Illinoyance · Jun 24, 2020

When the grinder is at rest any coolant that is absorbed by the wheel tends to collect at the bottom of the wheel resulting in imbalance. Jogging the spindle a couple time throws the absorbed coolant out of the wheel. I suppose the need could be eliminated by turning off the coolant a while before the spindle was stopped.

Paolo_MD · Jun 24, 2020

The main reason for jogging (or, in the case of VFD, to ramp slowly up to speed) is lubrication. Plain bearings need to have a proper film of oil to operate. If you spin the shaft too fast without re-establishing first such film, you get wear and damage.

Ball and roller bearings are much more tolerant since each ball/cylinder traps some oil by capillarity and they have mostly rolling motion against the surface that has most friction.

Paolo

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ah - now I get it

metalmagpie

Titanium

michiganbuck

Diamond

Illinoyance

Stainless

Paolo_MD

Stainless

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