Mill Assembly 02
More updates today:
Last night, I got a chance to rummage through my friend's scrap pile. (By the way, it's always advisable to have a friend with a scrap pile.) At any rate, I now have all the steel I need to make the primary frame, and have enough information to start building. I might be able to weld the vertical supports together this weekend.
I revised the mechanical drawing to reflect the available materials. The larger parts will be made from 1.5" square tubes, with 1" square tubes making the cross pieces. I have 4 or 8 (depending on how well the first 4 go) welded joints to do.
Another rather awesome coincidence is that I now have huge blocks of PTFE available to make bearings and anti-backlash nuts. So, now, my design isn't constrained around small .5" x .125" strips around which to build way bearings. I've beefed up the bearings that will now be solid plastic. The design can also fall back on brass bushings very easily if the lateral stress on the plastic turns out to be too much for the motors to push.
The unfortunate aspect of having nearly limitless amounts of expensive, low-friction, high-temperature plastic is that I now have a relatively more complex--although far better customized--anti-backlash nut design. The new design eliminates the need for a bracket, and gives a lot more working space for resisting the interactive torque between nuts.
The drawing doesn't show it, but I've decided to unify all my couplings by making them all out of .5" aluminum rods.
Finally, after pricing some aluminum blocks online, I'm scrapping the idea of a nice, solid-construction mill table. I'm not 100% sure of how it'll end up, but some hard wood, or possibly strips of aluminum can make a nice table.