Harmonic Gear Drive Reducer Small Strain Wave Gearbox Gearbox 100:1 Rotary Reduction Actuator, Fits Nema 17 Stepper Motor (Flange Output)

The product quality is good, works like a charm. I haven't got time to test its accuracy though, will update once I have time. But a few warnings for future buyers since this product doesn't come with any handbook, while the images on this web page are all information seller provides. I don't mind to share what I learnt so far: 1/ there're 4 missing screws, 2 M3 and 2 M4. If you'd like to have it work out of the box, prepare your own screws or contact seller beforehand 2/ during assembly, make sure of the right position, i.e. 15.35+-0.02mm on the 3rd product image, you don't want to destroy the wave generator 3/ during assembly, DO NOT USE FORCE, it's harmonic reducer, rotate wave generator slightly to find the right angle to combine the 2 parts. You may lose its precision otherwise

Just got mine, looks good, though as mentioned comes with zero assembly instructions. Also, currently struggling getting the wave generator disk onto the stepper shaft. Have to use my magnifying glasses to see if there is a slight burr where the set screws are as I can't push the disk past that. Will post again once I figure that out.

Hard to find a strain wave gearbox for NEMA17 at this price. Working well with plenty of torque, no discernable backlash (I have not done any precision measurements). A bit of roughness if I backdrive it, but this is not a problem for my application. The bit of gear grease it comes with was a handy addition. Overall I'm happy with it.