Pololu Universal Aluminum Mounting Hub for 4mm Shaft, M3 Holes (2-Pack)

These universal aluminum mounting hubs allow you to mount custom wheels and mechanisms to 4 mm diameter motor shafts. The set includes two hubs, two M3 set screws for securing the hubs to motor shafts, and one 1.5 mm Allen wrench for use with the set screws. Each hub has four threaded mounting holes for M3 screws (not included).

These universal mounting hubs are designed to work with most 4 mm diameter shafts, including round shafts, and “D” shafts. Each of the two included hubs has four mounting holes for M3 screws (not included), letting you mount custom wheels or mechanisms to your motors. The two included M3 hex set screws (one for each hub) allow secure coupling of shaft to hub, and a 1.5 mm hex wrench 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 Pololu’s 25:1 metal gearmotor 20Dx44L mm and a Pololu 20D mm metal gearmotor bracket. These hubs will work with any Pololu 20D mm metal gearmotor or 25D mm 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 20D mm gearmotor with bracket and hub.

Pololu 60×8mm wheel on a Pololu 25D mm metal gearmotor.

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