Here is a photo of a prototype Chiaphua motor mount. The dimensions are pretty simple:
Motor mount screws are 10-32, spaced exactly 2.00" apart
The center "bulge" is .75" in diameter
The centers of each gear (shaft, big gear) is .740" apart.
I mounted the cluster .75" from the center of the motor shaft and there is a bit of play. If/when I do this again, I will split the difference and mount the cluster .745" from the shaft.
This was all determined on my kitchen table with a caliper. I punched out the 1/4" plate with my milling machine (you need at least an accurate XY table) and press fit the 1/4" ground drill rod shaft.
Team #492