New Bearings For Mini Mill

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Zoltan

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Since I'm already replacing my mini mill's spindle, I figured I'd replace the bearings as well. The stock bearings were painted over and are cheap no-names. I'd like to install good Japanese bearings like NSK or SFK. My questions are:

1. Do I need to get ABEC-3 or ABEC-5 bearings? Almost everything available I see if ABEC-1.
2. What internal clearance do I need? From researching I think I just need normal clearance (CN) though a lot of aftermarket bearings are C3.
 
I'm no bearing expert, but from what little I know I think ABEC 5 might be overkill. Are the bearing pockets even bored straight enough in the head casting for them to shine?
ABEC-1 is electric motor grade, if you can I'd go for ABEC 3 but if you can only find ABEC 1 think that might be OK and maybe even better than factory. Any bearing experts please correct me if I'm wrong.
 
Looking at the stock bearings I'd argue any brand name Japanese bearing will be an upgrade.
 
Zoltan said:
Looking at the stock bearings I'd argue any brand name Japanese bearing will be an upgrade.
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I agree, most Chinese bearings don't last that long. ABEC grade 5 is a very high grade bearing, if you can afford them it's always nice to do things the best way. If you can't though ABEC 3 or even 1 would should be an upgrade, and with tighter tolerances would last longer too! :)
 
I've found SKF ABEC-3 bearings for a pretty good price and think I might go with them.

I've also considered going with angular contact bearings, but you can't get sealed or shielded brand name ones without paying a lot, and I think open one would have grease retention issues.
 
Zoltan said:
I've found SKF ABEC-3 bearings for a pretty good price and think I might go with them.

I've also considered going with angular contact bearings, but you can't get sealed or shielded brand name ones without paying a lot, and I think open one would have grease retention issues.
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Is there a way to preload the AC bearings? I think that might be the way to go then! :)
 
Well, I just found a supply of SKF ABEC-3 7206 angular contact bearings for a decent price, so they're definitely a player now.

The question is, how do you deal with grease retention when the bearing is on a vertical shaft? It seems like gravity would slowly pull the grease out of the bearing over time.
 
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