For the Main Ankles I’m using a 3/8″ threaded bolt, 2″ in length with a steel sleeve for the connection between the main ankle and foot, I didn’t want the bolt threads wearing away the styrene. The bolt has a 9/16″ head which I’ve marked for easy of finding the right tool in the future. I glued the washer onto the styrene facing the battery box, but there is not enough clearance for the nut and washer on the outside face. I’ve drilled a hole in the battery box to allow access for the bolt to be inserted and access to the hardware from that side. It is tight on the outside so getting the nut on the bolt is tricky until it starts getting threaded.
Here is a picture of the bolt/nut installed, notice the 9/16″ again on the inside so I get the right wrench the first time.
I’m going to be using the Jaycar motors ($40/each + $25 shipped) for both feet and the dome as recommended by Dave. I bought a 7mm/8mm ratchet wrench from Sears for $7. It works extremely well for attaching the motor support plate to the foot.
I ordered the wheels (T80P-493BG-HS6) and hubs (T80H-SM61) from BaneBots for $37 shipped.