Guys, I've been trying to come up with a process to improve the knurl on 1/16" hardened steel shafts. I basically want to knurl the shaft on the bottom to be similar to the one on the top in order to give it more bite into the brass gear on the right. The problem is that these .0625" O.D. shafts are polished hardened steel. A file won't even touch them. (I previously tried the method of rolling the edge of a file over them and it doesn't even make a scratch.) A knurl pattern would be ideal but I'd settle for anything that creates more bite. The shaft on the bottom is from an early Telechron rotor and the factory probably realized more bite was needed and then went to the design on the top. Any suggestions how to replicate this? TIA.