I'm working on my Z-axis, which need some additional panels attached to keep if from flexing (design flaw
). The problem is, there is very little extra room to mount the panels, but I think I have it figured out. I only have room for 1/4" plywood, which is kinda flimsy, so I'm laminating some aluminum skins (.025) on to the 1/4" with epoxy. I'm going to throw them into my vacuum press shortly, so they'll be ready to cut and mount tomorrow.
In the meantime, I made a jig to turn the ends of my acme down with a router table. I bought some 1/2" ID bearings from Mcmaster Carr, as well as some 1/4" shank grinding stones. I set my router to 10,000 rpm, clamped the jig to the router fence, and fed it into the stone while turning it by hand. I'm using rollerblade bearings, so I need an 8mm shaft. I soon realised that grinding the 1/2" down to 8mm would take a loooong time, and if I got to aggressive, the screw got very hot. So, I pulled out the screw, and using my 12" disk sander, sanded all the threads off in about 1 minute. Then back to the grinding jig for basically a finishing pass.
Now, this is not an extremely precise setup, as fine tuning the fence turned out to be a bit tricky. Because of the lack of high precision, I had to end up a little on the small side, but I was able to get a very good fit. The ground area is within .001 it's entire length, .312-.313. 8mm is .3149, so I'm within .002-.003. And the tranition into the threads is radiused, so the bearing self centers. I then used an 8mm die to thread the end, and mount a nylon lock nut. The bearing will mount to the bottom of the screw, with the outer bearing in a 22mm counterbore under a 1/4" aluminum plate, and the top bearing resting on top of the plate. Here's a few pics.