Pololu Universal Aluminium Mounting Hub for 4mm Shafts – #4-40 Holes (2-Pack)

We have an assortment of universal mounting hubs available, spanning several shaft sizes and featuring mounting holes threaded for metric or imperial screws. These universal mounting hubs are designed to work with most 4mm diameter shafts, including round shafts and “D” 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.

The product images show a hub with Pololu’s 25:1 metal gearmotor 20Dx44L and a Pololu 20D metal gearmotor bracket. These hubs will work with any 20D metal gearmotor or 25D metal gearmotor, and they also work with 60mm, 70mm, 80mm, and 90mm Pololu wheels (excluding the Multi-Hub versions; see the individual wheel pages for compatibility details).

Specifications

• Size: 19 mm diameter × 5 mm thick
• Weight: 3.2g*
• Shaft diameter: 4mm
• Mounting hole size: #4-40**

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