This is a PM-833 conversion with a Heavy Metal CNC kit just like Dr. D-Flo’s. My kit came with double ball nuts, so I don’t need to worry about that upgrade later.
I completely disassembled the mill which was a good opportunity to remove the vast quantities of cosmoline that shipped with the mill.
I started with the Z-axis and the only modification that was required on the mill was to drill and tap a hole to relocate the oil line manifold to accommodate the new nut block. No other modification to the cast iron was required on the Z-axis. I located the oil line manifold to require minimum re-bending of the oil lines.
The Y saddle did require a little grinding to provide clearance for the nut block assembly. I also had to do some grinding under one end of the table to clear the X nut assembly when sliding the table back on.
I did have some issues with the less than precise placement of tapped holes in the mill that others have noted. There was some mis-alignment with the holes in each end of the table. You can see the worst of it in the photo. That is the total misalignment that you see. I was able to use a round file and relieve it enough on both sides to get it to fit. There was just enough counter-bore to still fit the socket head screw.
The only significant problem I had with the kit was with all the screw brackets that were machined to carry the bearings. The minor bore diameter on those brackets was smaller than the major diameter of the inner bearing race. That caused the inner race to ride on the aluminum when assembled, resulting in a bunch of friction. I was able to grab the parts with the lathe and take care of that issue. Bruce at Heavy Metal says that bore has been enlarged now so you would not have this issue with any recent kits.
Overall, I’m happy with how this conversion went and would definitely buy a Heavy Metal kit again. I finished the assembly this weekend and ran some g-code to put the mill in motion. WooHoo! Now I’m on to the probe and tool height setter. I have some questions for Dr. D on that.