Time for another CNC! I can weld now, so this is a new game.
Another ad-hock, not-much-of-a-plan project. The idea is that the frame is really sturdy and ridgid, but not necissarily positioned right.
All the sliders are shimmed into the correct positions. Some ideas worked, some didn't, it came out great. I need to move the upprights back as
the X-Z assembly was deeper than I expected, but it worked fine! I built a pendant for it. The PLA printed sliders are STILL holding! I decided
 to go with PLA sliders after looking at the CNC machines on sale from china. 
The spindle motor is brushed. I don't expect them to last a long time, but they will be cheaper than a brushless + controller. 
The failure of the first motor was not the brushes, but the bushings! The speed controller ramped the power up so hard as the armature was grinding 
into the field magnet, that it burned up the windings. WOW.
The spindle speed controller is a tiny13 emulating an LM2907 with a proportionate loop and pwm output.