One other thing to watch for when replacing Z-axis bearings: If this has a "Dow Frost' spindle chiller, make sure dow isn't leaking on screw. We replaced bearings on our 4020 about 5 or 6 years ago, and discovered a hole in dow line was the problem... it was leaking coolant onto the ball screw which quickly wasted the bearings. We haven't had a problem since - and yes, we ordered bearings from a bearing company (just took old ones in and cross referenced them). |