Losmandy GM8 Belt Drive Stepper Motor Mount

thingiverse

UPDATE Over the past few days, I've been refining this design and implementing some significant changes. Stepper mounts are now integrated for both RA and DEC, and a single belt cover design that fits both stepper mounts has been perfected. Additionally, on the inside of the cover, an insert for an additional F625ZZ flange bearing has been designed to provide extra support to the pulley shaft. The shaft can now extend beyond the 60-tooth pulley and into the bearing in the cover, offering a more secure fit. This is a NEMA 17, belt-drive, stepper motor mount specifically designed for the Losmandy GM8 mount. As I built it, I used a 15-tooth gear on the motor and a 60-tooth gear on the 5mm shaft, resulting in a 4:1 reduction ratio. My primary goal was to prototype a design that could be later machined from aluminum, but I'm confident that this design can work effectively if printed from ABS/PET-G or Nylon for an extended period. However, I wouldn't recommend printing it from PLA as the results would likely be short-lived. I created this motor mount with the [OnStep telescope motion control system](https://onstep.groups.io/g/main/wiki/home) in mind. This versatile system is capable of controlling a wide range of telescopes. This design was made using Fusion 360, and I've included STEP cad files for those who may need them. You can view the RA 3D model [here](https://a360.co/2RkfZts), and the DEC 3D model [here](https://myhub.autodesk360.com/ue29882e51/g/shares/SH919a0QTf3c32634dcf1146410b25a5d98f). Other formats can be downloaded from these links. I used the following components: 1x 15-Tooth GT2 Gear (https://www.ebay.com/itm/2pcs-GT2-Aluminum-Timing-Pulleys-15-Tooth-5mm-Bore-for-RepRap-Prusa-3D-Printer/263570210647?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649) 1x 60-Tooth GT2 Gear (https://www.ebay.com/itm/GT2-Timing-Belt-Pulleys-60-Tooth-60T-5mm-Bore-for-RepRap-Prusa-Mendel-3D-Printer/263430555628?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649) 1x 200mm GT2 Loop Belt (https://www.ebay.com/itm/GT2-Timing-Belt-Annular-Loop-Cogged-Geared-Rubber-6mm-Width-2mm-Pitch-200-2GT/142603517023?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649) 2x F625ZZ Flange ball bearings (https://www.amazon.com/gp/product/B07MKFGS8Q/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1) You'll also need a 5mm shaft for the 60-tooth gear. The one in the design is 40mm and should be sufficient.