Star Tracker Build: the 100:1 reduction Harmonic Drive gearhead arrived today, and I'm planning out the mechanics for the direct drive train and structure for a case (3D printing a prototype case that will hold everything together tonight). Harmonic drives are the way to go if you're looking for extreme precision, zero backlash, and just plain cool technology: https://www.youtube.com/watch?v=3mWemlMEzFk I will be using the original iOptron CEM25P saddle for testing, and the threaded holes in the harmonic drive line up neatly. Gearhead specs here: http://www.harmonicdrive.net/products/servo-mount-gearheads/harmonic-drive/csf-gh/14/csf-14-100-gh
Electronics project for the day: prototyping the drive system for a direct-drive star tracker. This will be driving a 100:1 ratio Harmonic Drive gearhead. For this test I'm using a NEMA 11 stepper motor, also geared down, and a cheap A4988 stepper driver, but I will be experimenting with others.