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

by Pololu

These universal aluminum mounting hubs allow you to mount custom wheels and mechanisms to 3mm 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

These universal mounting hubs are designed to work with most 3mm diameter shafts, including round shafts, “D” shafts, and Tamiya’s 3mm 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.


  • Size: 17.5 mm diameter × 5 mm thick
  • Weight: 2.8 g1
  • Shaft diameter: 3 mm
  • Mounting hole size: #4-402

1For a single hub only (without set screw).
2This is also the size of the set screw.