I posted this in my build thread as well, but I think it's a relevant topic for most mills so I decided to make a separate thread for it.

background info:
I have a cnc'd PM45M that I'm finally getting around to doing a pulley conversion on. I've installed the typical 7206 and 7207 bearings that almost everyone who does this seems to use and I'm trying to test the pre-load of the bearings by running the spindle in my lathe. I originally started out with a special high speed NLGI.5 lithium grease but due to my issue I have switched to a thicker NLGI 2 lithium based grease.


that brings us to "The issue":
As I start running the bearings all the grease gets pulled thru the bearing leaving the races dry-ish after about a minuet or so. It's to the point where I can hear the difference in the bearing. It's much more noticeable on the upper bearing, but after removing the dust cap the bottom bearing also seems to have this issue to a smaller extent.

So has anyone else noticed this happening? I know a lot of people use kluber isoflex nbu 15 when doing this conversion, but i'm not shelling out that kind of money until I can get the grease to stay in the bearing. I've been tossing around the idea of removing the bearing and making a shield to instal under the bearing, but I'm lazy and I don't want to jump to removing the bearings if I don't have to quite yet.