A working diesel in 1/5th scale
You really are ambitious!! In all of the years that I have been going to the N.A.M.E.S. show in the Detroit area, I have never seen a miniature working diesel. The N.A.M.E.S. show is a model engineering show for working miniatures of all sorts of engines. I am going to be watching this build very closely.
Your drawbar broke! Without knowing how much of a cut you were taking but a Bridgeport mill is not going to handle much of a cut with a 1" or larger end mill for very long unless you are using a roughing end mill.