Which bearings for a grinder?

[Grindstone CowboyParticipant @grindstonecowboy]

Was recently given a double ended bench grinder which needs new bearings. The existing ones (pretty sure they're original) are metal shielded both sides. Just wondering if there would be any advantage in getting rubber sealed ones instead – the cost difference is neglible.

It's an Ajax unit, 750 watt, looks to be from the 60s or 70s. There may also be an issue with the capacitor, but one step at a time…

Thanks, Rob

[Grindstone CowboyParticipant @grindstonecowboy]

Shielded or sealed?

[not done it yetParticipant @notdoneityet]

Can’t ell how much work it might have done since new, but how long are you expecting it to last? I would not be surprised if the lube has simply dried out a bit over that period. Go with the bearing supplier’s recommendation – bearing quality is likely a better metric.

Running out of balance could be another reason for the bearings to wear.

Edited By not done it yet on 30/10/2021 19:38:51

[AJAXParticipant @ajax]

I'd like an Ajax unit — it would go with my forum nickname.

Capacitors are easy enough to replace, and if it still has the original one then it's probably about time.

[Howard LewisParticipant @howardlewis46836]

Since grinding dust will be flying about, 2RSS would be my choice. More friction, but I'd live with that.

Probably bearings worn because they are shielded rather than sealed

Howard

[David George 1Participant @davidgeorge1]

Hi I replaced shielded bearings with rubber shielded bearings on a grinder and the bearings heated up the housing quite a lot. Slight friction of rubber shielding at that speed caused heat. Check with a proper bearing supplier as to correct bearing. Right bearing right place. With metal shielded bearing it is still sound ten plus years later.

David

[martin haysomParticipant @martinhaysom48469]

if the originals lasted 50/60 years i would stick with the same type

[Grindstone CowboyParticipant @grindstonecowboy]

Thanks everyone for your advice. Good points from David and Martin, you've convinced me to stick with shielded. If they wear out again before I do, I can always replace them again

Rob

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