Carbide Burr Set with 1/4" Shank and 2/5" Head (10MM), CBTONE 5 PCS Double Cut Tungsten Carbide Rotary Burrs 1/4 Inch 6mm Shank Die Grinder Bits for Carving, Polishing, Engraving and Drilling

Eats through metal. Hopefully they last a long time

good price

I have a 75 year old drill press. Massive and stiff. I mounted an x-y adjustable work vise to the drill table and used these carbide bits to turn it into a crude end mill. I have cut wood shapes and aluminum shapes. When cutting aluminum you have to make very shallow cuts, so there will be more passes than with real mill bits. My drill does not have the speed or torque a real milling bit requires but these carbide burrs work well and have not gone dull.

The tile installer didn't quite get the clearance right for the Moen valve. The bit made quick, dusty work of the tile and backer board. I don't really know how long it will stay sharp because my project is finished and they are in the drawer.

Good quality rotary files at a reasonable price. I've used mine a couple of times so far in a cheap die grinding tool. They file great and appear to be remaining sharp and holding up/