Painting Stationary Machinery

Guys in the pass couple of yrs I have found myself purchasing old woodworking machinery and restoring them.Most of the machinery is from the 60's up to present.I have always use SW's Indus.Alkyd for primer and the indust.for the finish coat.I'm use to spraying the oil base paint using my Binks Mach I and Devilbiss GFI which both of these setups allows me to spray just afew parts or awhole lot.My routine is to sandblast the old paint off,wipe down with acetone then spray on two or more primer coats.Then after afew days spray on couple of finish coats over a two day period.Problem:As time has gone by(1yr or so)I have notice that the oil base paint still scratches easy either something hitting it or my finger nail rubs it.I have come to the conclusion that maybe I'm doing something wrong.I am game for change,with my next project being a 1946 bandsaw I would like for the finish to last along time.What product does the neighborhood SW's store have that I could purchase and the finish would stand the test of time.If you have any suggestions on my routine that I may need to change to help improve the longivity,please let me know.Heres a pic of my up coming project---Thanks CJ Courtney