Major progress for GUS today; I discovered that the hysteresis was a little bit from the too-low tension and a lot from very slightly loose pulleys. Just a tiny wobble in the pulley means a significant position error.
Having created access holes in the motor arms with a soldering iron and cranked the screws tight, I was able to get a much better set of calibration points and much improved prints, like the moai here.
I still have a calibration issue to deal with; square things aren’t square, so one or more arms have slightly different steps/mm. Of course that shouldn’t be the case, but with printed pulleys I gather it’s not too surprising. Tracking that down will be the next job. . .
