Belt-less, helical gear focuser for 135mm f/2
Description
This focuser aims to solve a couple of problems: 1. Aside from the motor, it needs no parts (belts, gear, etc) 2. It stays fixed to the lens (not unique, but useful) 3. The gear design increases contact patch, reducing backlash 4. Pressure is adjustable by simply rotating the motor 5. Compared to belted designs, it doesn't suffer from temperature changes Instructions - Print with whatever prints well, it isn't too demanding. I did .2 and .16mm with success - Make sure the motor axis juuuuust doesn't fit in the driving gear (small). Then, insert the shaft by heating it. That will ensure exact, backlash-free fit. Yes, his means the gear will be "disposable" but it's already super tiny and quick to print. - Spend a decent amount of time finding the correct gear pressure. Too little, and it'll have backlash. Too much, and it will have unnecessary friction, leading to stalls. Materials needed: - PLA - 1x cheapo 28byj-48 stepper motor, but modified (https://ardufocus.com/howto/28byj-48-bipolar-hw-mod/) to run at 12v and make it compatible with TMC2209 drivers. 5v doesn't quite cut it, anyways. It's designed to stay fixed to a Rokinon / Samyang 135mm f/2 lens. It works well on an OpenAstroTracker (https://openastrotech.com/). Please let me know if you have any suggestions or specific fit requests, I'll do my best. Source files are here: https://www.printables.com/model/384386-belt-less-helical-gear-focuser-for-135mm-f2
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