Yesterday I drilled the holes needed for the wiring in the top of the outer feet and started work on mounting the caster wheel in the center foot.
Before and after. Used a half-inch drill bit.
For the center foot, I needed to make a block big enough to secure the caster to and extend it enough to get the proper height from the ground. Most builders extend the wheels out about 1.5 inches so I'm doing the same. To obtain this, I made a wood block out of 3 half-inch thick pieces of plywood. The top block I made to fit the inside of the foot while the next two blocks are the same size as the caster wheel's mounting footplate. I have two more pieces to make which will provide a way to secure the main block within the foot.
I'll share the measurements and other details once I prove this setup will work.
I've also started designing the head rotation motor bracket and have ordered the wheel for this motor. Basically the wheel will rest against the inside of the Rockler bearing and make it spin. I'll be using the scrap aluminum from the foot drive.
Soon I'll be able to order the main wheels for the foot drive and then R6-C9 will be able to walk for the first time. It will be a true milestone for this project. I can't wait.