Harmonic Gear Drive Reducer with Nema 17 Stepper Motor 1.4A 2 Arcmin Ratio 30:1 Rotary Gear Reducer

Harmonic drives are normally very expensive. I have had my eyes on these for a little while and finally had a project that could use a three of them. There is a lot to like, they are compact, nearly silent with a low noise driver, and easy to drive. I really like the top plate, and wish more motors had a similar design. They claim 2 arc min backlash and they have no percieveable backlash. Also at $125, they are a fraction of the cost of a typical harmonic drive. I could imagine these being very useful in many applications. In my case i was working on a motion control robot for a client, and the issue comes in when you start to drive them with any load, the movement starts to sort pulse. The load was 100% suppported by a large RU66 style german bearing, and all these motors had to do was apply a rotational force to the rotational side of the bearing. All metal contact through out, and as soon as things started moving it would start to pulse. I added a mechanical damper to add a little extra resistence to the motor which did help, but unfortunatly the issue was still noticable. I swapped them out for a couple worm drives and the issue cleared. They worked better at extremely slow speeds < 2-3 degrees per second. I imagine these would be super handy for many purposes, but if you need consistent smooth confidant motion. Keep your load requirements very light.