I have to cut a .064" deep step into some 2"x.75" case hardened steel pieces. The hardening is about .015 deep. The cut goes from the bottom edge in about .65 at a 15° angle across the bottom. The step must be square so a sharp cornered tool is necessary.I was using an uncoated carbide Atrax 2 flute 1/2" endmill at 2500rpm and 3.5fpm feed, and a flood of ValCool, but after 4 pieces there are no corners left on the endmill. I need to do 250 of these. The machine is a Cincinnati 5vc-750 (5HP).