Pololu Universal Aluminum Mounting Hub for 3mm Shaft, #4-40 Holes (2-Pack)

These universal aluminum mounting hubs allow you to mount custom wheels and mechanisms to 3 mm diameter motor shafts. The set includes two hubs, two #4-40 set screws for securing the hubs to motor shafts, and one 0.05″ Allen wrench for use with the set screws. Each hub has four threaded mounting holes for #4-40 screws (not included).

Mini gearmotor with bracket and hub.

These universal mounting hubs are designed to work with most 3 mm diameter shafts, including round shafts, “D” shafts, and Tamiya’s 3 mm hexagonal shafts. Each of the two included hubs has four mounting holes for #4-40 screws (not included), letting you mount custom wheels or mechanisms to your motors. The two included #4-40 hex set screws (one for each hub) allow secure coupling of shaft to hub, and a 0.05″ hex wrench (often the smallest size in SAE Allen wrench sets) is included for use with the set screws. A dimension diagram of the hub is available under the resources tab.

The picture to the right shows a hub with one of Pololu’s mini metal gearmotors and a Pololu mini metal gearmotor bracket. These hubs will work with any Pololu mini/15.5D mm metal gearmotor or micro metal gearmotor, and they also work with 60 mm, 70 mm, 80 mm, and 90 mm Pololu wheels (excluding the Multi-Hub versions; see the individual wheel pages for compatibility details).

Pololu Wheels with 90, 80, 70, and 60 mm diameters in three colors: blue, red, and yellow.