Simplified SERB wheels and caster

This drawing is for two simplified wheels and the original caster design for the SERB robot. We intend to print the red in a different color acrylic, so will ignore them in our current project (the red also includes enough spacers for an Arduino or other board).

The driver for these changes from the original was cost. Cutting time costs us more than material, so the large wheels were modified to remove extra cuts.