The Pololu universal aluminum mounting hub allows you to mount custom wheels and mechanisms to 3 mm motor shafts. The hubs are sold in pairs, and each hub includes one 4-40 set screw for securing a motor shaft to the hub.
These universal mounting hubs are designed to work with most 3mm shafts, including round shafts, “D” shafts, and Tamiya’s 3mm hexagonal shafts found on the Tamiya 70097 Twin Motor Gearbox Kit and Tamiya 70168 Double Gearbox Kit. Each hub has four mounting holes for 4-40 screws, letting you mount custom wheels or mechanisms to your motors. 4-40 hex set screws (one included for each hub) allow secure coupling of shaft to hub. The kit includes set screws and a 0.05" hex wrench (often the smallest size in SAE Allen wrench sets).
We also stock #4-40 machine screws of various lengths that can be used to fit wheels to these hubs.
Mechanical drawing for the Pololu universal aluminum mounting hub for 3 mm shaft