...aaaand that's about all I can tell you for now. It's made, it's assembled, and it's running on my desk. There's no discernible backlash - as promised!

at 55:1 reduction on my 200 step per turn motor at 1/16th microstepping we're looking at 176,000 steps per rotation, or 0.002 degrees per step. It ain't fast, and it don't need to be.

The first prototype cost $1050 CAD. The next five I'm told will cost ~$200 each. Once I get that far and have a demo arm, there will probably be a kickstarter for the gearbox.

The challenge now is testing this thing to see how much torque it can handle. I need to make a pillow block to hold both ends of the output shaft so that all the force on the motor is just rotating torque force, then attach a bar and start hanging weights off the end until it can't move any more. Repeat for different speeds.

I'm planning a single joint with two rotations. Three joints is 6DOF. Length can be increased by adding space between the joints.