I know this has been discussed, but I couldn't find anything when I searched. I am going to make an ER 40 collet chuck that will be a direct mount on my lathes L00 spindle nose. This will be for occasional use in the home shop. The material will need to start out as a 3.75-4" diameter about four inches long. I don't have the facilities or the money to have it heat treated. My thought was that 4140 annealed would probably be the best from a wear, machinability, and avialability perspective. 4140HT seems the best from a toughness aspect, but how is it to machine? Cast iron would be cheaper, but doesn't seem hard enough. What say you?