In my quest to adjust the alignment of my Omni, I discovered that there were a few different issues at hand.
- The Mast is not perpendicular to the Base Plate
- The Base Plate is not flat
- The Platen is not perpendicular to the Mast
- The Swing Arm has flex/play in it
- The Platen has excessive vertical runout
- My Spindle appears to be bent
Because at the time I started my alignment I did not know about issues 1, 2, and 6 decided the best thing to do would be get my Platen machined to take out the hop. In order to do that I needed to remove the Platen and Spindle from the machine.
After having the Platen machined (and made smaller) I discovered that there still was a significant Platen hop of 0.0035″ (3-1/2 thousandths of an inch). Half of what it originally was, but much more than the 0.001″ tolerance the Platen was just machined to. After a bit of monkeying around I came to the conclusion that the Spindle may be slightly bent near the top, just under where the Platen sits.
Update: the Spindle was not bent. The Spindle diameter was too narrow to fit snugly into the bearings of the Spindle Housing which meant that it wasn’t held tightly and wobbled when spun.
I set about trying to align the Platen to the Faceting Head by putting a dop in the Quill and adjusting the angle and height of the head so it barely touched the Platen above one of the Adjustment Bolts. Visit the Omni Platen Alignment page.
After thinking I had the Platen aligned, I tried cutting a test stone and realized that the Mast was not perpendicular to the Platen and I set about trying to figure out how to align the Mast. It was then I discovered that the Base Plate was not flat. And after some thinking I came across what appears to be a workable solution to that. Visit the Omni Mast Alignment page.
All told, I have spent about 2 weeks on and off getting parts machined and probably 5-6 hours actually getting parts aligned to each other. At this point I’m reasonably happy with my work but still have some ideas left to try.
I should add that after all these alignments (and documenting them for this site) I haven’t had a chance to cut a rectangular stone to see if the problems I was having are reduced. I’ll post my results of that when I get a chance.