I have collected quite a few used HSS tool bits from ebay including a bit already ground for external threading. However I am in need of an internal threading tool. In my previous questions I ended up going with HSS tool bits mainly due to the speed my lathe is capable of achieving (500 rpm) as well as wanting to learn how to grind my own tool bits. The part I'm going to be internally threading has a bore around 1" diameter. I've been looking at late tools on the various places, MSCDirect, Shars, CDCO, Amazon, etc. It seems that about the only tools available for internal threading are tools with carbide inserts. Are these the only options I have? Is there any issue with using this with my slower lathe? From my watching of videos and reading, it doesn't seem that threading is done at super high speed anyway. Any other suggestions or things I don't even know?