Ive had a problem on this last batch of 321 SS parts that ive ran. For some reason even though i am using the recomended SFM for 321 which is 55-90, as well as a feed rate of .006 to .008 for a drill between 3/8 and 1/2, drills keep getting destroyed. They will run 20 or so parts then the tips will be gone. Material that it is going into is clean, using carbide drills, as well as high speed steel, the results were still the same. I adjusted the speeds and feeds during run, however nothing ever got me to that sweet spot. I was wandering if anyone else has ever had this issue. This was on a cnc 2 axis lathe. Ø.421 for the drill.