Originally Posted by Hired Gun
While I don't have your experience or knowledge of machinery for sure, I know my Starrett .0001" indicators can be made to run dead smooth no movement on things we dial in or have cut. As one famous smith once told me, it's way better than what's needed for gunsmithing. We are not making diesel injectors here.
I wasn't so much knocking your setup (your business), but figured you got too many zeros. I once scraped in a Southbend, and seriously beefed up the bench work it was mounted on (similar setup to what you are using) by adding a ground 3/4" steel plate under the entire lathe. Had to make a new drive belt of course. Then made two more plates for the bench to go between the it and the floor. It would hold .0003 to .0006" all day long till it got some wear in the slides. Then it was a steady .00075" machine with high speed tooling. I could have gone in there and tweaked the bed a little bit and maybe picked up another two or three tenths, but it was plenty good enough for what it was being used for. The idea was to leave about five to seven thousandths of stock on the parts to save labor cost in the next operation. Prior to that they were leaving about twenty thousandths on Rex M2 and Speedstar.
The frame design on the Hardingh bench lathe is very stiff, and I honestly thing that's 70% of why they are so accurate. By the way the only machine I've ever seen with less lead error in a thread form was an Excello thread grinder! But if I were ordering a new lathe this afternoon, it'd be a Colechester