i tap a lot of stainless, and i have had to do a lot of blind holes and have had the best luck using molydee and a slow spiral flute tap with a 3 thread chamfer or lead, and the cutting face hook or rake angle has to be 10-15 degrees. in deeper hole applications greenfield has sold me taps with a interrupted of releived thread and they have worked great. all the taps i buy are either greenfield or emuge, nobody else has shown me a better tap than these two companys |