Mill: Bearing Seal

A surprising amount of shavings make it up to the bottom of the mill head. When I was using open bearings, even with a shield in place they became contaminated. Even though I'm using sealed bearings now, I wanted additional protection. So like on the lathe, I made a new bearing cover for the mill which accepted a standard size oil seal.

For a MT3 spindle you want a 40x55x5 oil seal.Since the bearings are sealed, I didn't need the oil seal's inner lip, so I cut it off to reduce friction. The seal could actually have been pressed into the stock plastic bearing cover, but I figured aluminum would be more durable and prevent potential problems in the future.

If you want to run open bearings on the mill you'd pretty much need to do something like this to retain the grease and exclude contaminants. If you have a R8 spindle and upgrade the bearings, this is almost a mandatory upgrade since I've only seen open 7007 AC bearings.

Bearing cover with oil seal installed on the mill.