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Old Mar 16, 2012, 03:50 PM
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So, if a person was using thick high viscosity grease, probably the easiest/best method to clean and "re-pack" the grease is to force new grease until old the old grease is out, followed by a stand-alone bench "run-in" to sling off excess grease, as shown in Bob's video posted above.

However, I watched a "related" video showing the Bearing Blaster, and saw it is intended for thin low viscosity oil, where it's probably easiest/best to clean old oil and grime out from a bearing by using a solvent agitated bath, followed by a new application of fresh oil.

The videos made me question which of the two different types of lubrications should be used? I think historically before 1970's, grease was commonly used on heavy duty stuff, like automotive wheel bearings. Back then, people routinely manually re-packed grease into their wheel bearing like Bob showed; however I think around the 1970's, automotive wheel bearings started being shipped as sealed for life, and inside the sealed bearings, thin low viscosity oil was being used. I think the "old school" reasoning for using grease was because having a big glob of thick grease fill up the void inside the Bearing cavity acted as a barrier preventing outside water and grime from getting into the void where the balls were; whereas if lightweight oil is used without use of a seal there would be nothing to stop water and grime from getting in. I think back then it was recommended to have unsealed wheel bearings re-packed with grease every 12,000 miles (~ once a year); whereas today's sealed oiled bearing have a "no-maintenance" lifetime of +100,000 miles.

Probably thick high viscosity grease offers more resistance to movement then thin low viscosity oil (especially at low temperatures); therefore grease would probably only be preferred in un-sealed bearings mainly for its use in helping keep water and grime out; whereas, oil would probably be preferred in sealed bearings.

Also bearings intended for use with small weak forces probably would do best with thin low viscosity oil rather than thick high viscosity grease.

So ....

Since my micro heli's have open bearings, and the Motors seem strong, I'll grease the Bearings the way Bob showed, mainly to add a seal/barrier to stop outside grime from getting inside the bearing.

Since my electric Motors are nearly sealed and I don't want to and/or can't pack grease inside the electric Motor, I'll continue using electric Motor oil so it can wick on to the Bearing/Shaft surfaces.

I think I learned something today, and will start becoming a "greaser"

Thanks HF
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