Created this as a side project to learn OnShape a bit better and how it integrates COTS models with custom parts. Since our team already has 10in mechanum wheels I decided to try and upgrade the AndyMark KOP chassis with the larger wheels. Unfortunately these wheels are extremely heavy so we’ll see if they get used at all.
In order to fit the larger diameter, the upper flange of the inner side rail and both flanges of the end rails needed to be trimmed. This results in both a severe loss in bending stiffness to the side rail at the gearbox, and a loss in shear capability at the corners of the end rails. To restore some of this capability, the churro tubes are replaced with an upper web and lateral stiffeners. The web helps react shear through the two side rails, and the lateral stiffeners take place of the churro tube in reacting bending along the upper flange. Riveting the stiffeners to the web also helps prevent buckling in the plate.
Finally, a belly pan and motor controllers are added to complete the assembly. The motor controller mounts are meant to be 3D printed and zip tied.
Overall, the delta weight with the added structure is not that significant, but further steps could be taken to reduce overall mass, including using smaller wheels.
Regardless of if our team uses this I think its a good exercise in learning how trimming material can impact structural integrity and how simple, lightweight structures can be used to restore that capability.