Mini Mill Z axis #3

This is my third and final Z axis. Based on a comment on my original Z axis, this drives the "precision" worm screw. If you didn't snort milk through your nose when reading the scare-quotes, the precision drive is anything but precision - mine had about 0.040" slop. However being the Z axis you can leverage this wonderful thing called "gravity" so as long as you have positive down-force (gravity, air cylinder, can't it be both?) then you can (almost) guarantee the same side of the screw will be forcing against the same side of the gear, and you won't have to travel the backlash to reverse directions. If this doesn't make sense, tighten up the gibs real tight on the Z axis travel and move the precision vernier. you should feel dead space where you move but the mill doesn't. Now loosen up the gibs, the head might lurch down, and now whether you turn up or down, it should move with your movement. The backlash is eliminated because gravity is pushing the head down keeping the gears meshed