Hi Gary , I use a .250 dia carbide 2 flute mill drill, with a 60 deg point angle. I do most of my engraving in aluminum, 9000 rpm at 5.0 ipm plunge and a conservative 10.0 ipm feed rate. The depth is .024 for most text. If you want wider text use a .250 dia carbide 90 deg
point mill drill, same...