Originally Posted by CarbideBob  Commercial toolholders will normally be 4140, typically heat treated to 42Rc but just about any steel will work for low volume uses.
Milling cutters are often made from 4140 pre-hard because they warp too much in heat treat.
Bob |
The bolt on tool holders and boring bar holders on Haas machines are definitely not 42Rc and they do not machine like 4140. Similarly all the tool holders on the manual machines I used to have were all non-hardened low or medium carbon steel. Milling holders are a different thing they are hardened and ground.