sharpening end mills by hand.

[Terry S]

I confess to doing this as well. Usually it is the bottom cutting edges of HSS roughing mills that I have to touch up. I use one of those 3M diamond files with the plastic handle. I like the "yellow" handle which I think is about 600 grit. About 3 pulls on each edge gets them back to cutting fairly well. Take care to use the same number of strokes on each edge, and try to hold the original angle of the edge.