This is 2.5" x 2.5" Aluminum tube with a 1/8" thick wall. We machine it to a custom length. Using two of these you can make your custom sized robot. They support our ATR Wheel and Shaft Set Pair 12mm bore - 10 inch. Two motor adaptor plates are provided with hardware to mount IG52 planetary gear motors to the chassis side. The width of robot is up to you, it must be at least (the length the gear motors + 2.5" tube + 1/8" adaptor plate) x 2. A simple piece of plywood, aluminum, or acrylic can be used to tie the two side together or the sides can be bolted onto your own robot chassis.

The tube structure uses the bearings in the above linked wheel kits to support the axle. The other side of the axle is supported by the motor. This provides a much stronger attachment for the wheels and the load is put on a heavy duty bearings and tube instead the motor. Direct coupling a wheel to the motor will just ruin a motor quickly.

Below you can specify the center to center length of the side. This will be the distance from one bearing/axle to the next. Specify the center to center length of the axles in inches. Total length of side will be an additional 4 inches. (i.e. there is 2" of tube past each axle center. The maximum center to center is 32.5 inches, the minimum is 11 inches.

For dimension detail about the motor mounting holes, please see the engineering drawing.