The most recent success in my ongoing RF-45 mill repair project is the fabrication of a new Y-Axis lead nut. The stock nut was apparently lost somewhere along the way during the attempted CNC conversion that I’m partially reversing, so I had to come up with a replacement.
My first thought at replacing the nut was to make a new one out of acetal plastic based on the method described at the Home Shop Machinist Forum. On second thought, I decided it would be much more practical to see if I could find a replacement part online. Like many of the chinese machine tools out there, this mill is one of many clones of an original design. In this case, the Rong-Fu 45 is the original, and my copy was produced by Penn Tools. Unfortunately, I was unable to find replacement parts through them, but Grizzly sells a similar mill along with replacement parts. I dug through the manual to find the part number, contacted Grizzly, and ordered the nut. Easy enough right?
Unfortunately, the importer of my mill chose to use 8 TPI leadscrews, while the Grizzly version uses 10 TPI leadscrews, so the nut didn’t work. I returned it to Grizzly, and set off on my original plan of making the nut from scratch.
I started by boring and splitting the acetal to fit the lead screw: