Mini Mill Z axis #3

thingiverse

This is my third and final Z axis. Based on feedback from the original comment on my first Z axis, this drives the "precision" worm screw. If you didn't chuckle when reading the scare-quotes, the precision drive is anything but precise - mine had about 0.040" slop. However being the Z axis I can leverage that wonderful thing called gravity so long as I have positive down-force (gravity, air cylinder, why not both?) then I can almost guarantee the same side of the screw will be forcing against the same side of the gear and 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 on a common face. Now, so long as I have right-handed tooling in a right-handed mill, the tooling will suck down into the part. Facing operations and drilling too fast you may experience some backlash. Slower speeds and higher feeds help alleviate this problem or augment gravity with an air cylinder. Anyways for what I'm doing this is a pretty ideal solution and simple to implement. You need to knock out the pins in the linkage between the worm gear and the dial then insert the coupler between. You'll notice in the pictures I'm not actually using the coupler I did test it but given the print direction it snapped eventually. I machined this on the lathe with 1" stock hence why its so damn thick I'm lazy and only reduced the OD where it interfered with screws and couplers. X axis: https://www.thingiverse.com/thing:2586512 Y axis: https://www.thingiverse.com/thing:2591938 Original Z axis: https://www.thingiverse.com/thing:2639892 I think long term I'd prefer a ballscrew drive but this is better than my old leadscrew drive and should allow me to fabricate a proper ballscrew mount bootstrapping.