Sharpening End Mills On The Lathe

[hemmjo]

Very nice. I know people say you are not supposed to do grinding on a lathe, but if you are careful and clean up when finished, it opens so many possibilities.

I have been wanting to get a CBN to use for sharpening on the lathe. As I understand the do not release grit that can damage the lathe. Has anyone done that? I don't know enough about CBN wheels yet to know that to purchase. They are pricey.

[tonyfoale]

Very nice. I know people say you are not supposed to do grinding on a lathe, but if you are careful and clean up when finished, it opens so many possibilities.

I have been wanting to get a CBN to use for sharpening on the lathe. As I understand the do not release grit that can damage the lathe. Has anyone done that? I don't know enough about CBN wheels yet to know that to purchase. They are pricey.

I use CBN and diamond wheels. Neither wear very much at all. I have probably sharpened hundreds of milling cutters, drill bits, engine valves and tappets etc, and the only visually obvious wear is a slight rounding of the edges.
Most people have the wrong idea about grinding debris. Most of it is the steel that you have ground away, only a tiny proportion is grinding wheel grit. If it were mostly wheel grit then the wheel would be wearing way too fast. Of course the opposite applies when dressing a standard type wheel, then it is all wheel grit.

When grinding on a lathe or milling machine I cover where applicable and directly under the wheel I put some flat magnets and cover them with a wet towel. That catches everything. Another implementation of the magnet idea is shown here DIY surface grinder if you scroll down the initial post.

Click for full size.
Magnets attached to the aluminium wheel cover with tape. When the tape is removed the deris just drops out.