Fingertech Wheel Hubs
Fingertech hubs are one of my favorite ways to attach wheels to motors. There are two main variations, the original "Snap Ring" design, and the updated "Twist Hub" design.
Both variations come in Thin (0.5 in/12.7mm) and Thick (0.75 in/19.05mm) variants. The Snap Ring design can be mounted to motors with 3mm (.118 in) and 4mm (0.157 in), while the Twist Hub design can mount to both of those, but also 6mm (0.236 in) shafts.
This wheel system is a foam wheel system, where the foam acts as both a shock absorber when landing from height, and also tends to be cut or broken apart rather than deforming, thus these wheels are very resilient.
Snap Ring Design
This version, usually colored red, features a large flanged edge attached to a cylindrical core, along with a washer. A foam wheel is placed over the core, then the washer is placed over the wheel. Ensure that the depression in the washer faces out, then place the snap ring over using a pair of "snap ring pliers," such that it fits into the groove on the core and prevents the washer from coming off.
My robots that use Snap Hubs:
- Blastwave_I
- Thwackintosh
- Blastwave_III (repurposed parts and added pulley to wheels, but its the same design)
Twist Hub Design
This version, usually colored blue, features the same large flanged edge attached to a cylindrical core, but it also has two small protrusions opposite the flange. also included is a washer with some complex cutouts and depressions. The wheel is placed over the core, then the washer is aligned with the protrusions and slipped over. The wheel is then squished and the washer turned, such that the protrusions on the core are captured in the depressions in the washer. There are two small depressions that aid in the twisting operation. Fingertech does sell a small tool to aid in the twisting, but I've also been able to twist it with a pair of needlenose or snap ring pliers.
A later revision also added ribs that stuck out of the core to prevent the wheel from spinning on the shaft, and most hubs sold now feature this.
My robots that use Twist Hubs:
Foam Wheels
The wheels themselves are foam discs, which can be purchased from Fingertech directly, or from other suppliers under the "Lectra Lites" and "Lite Flites" names. If you need a specific size of wheel that isn't an offered size, I have had luck taking foam tiles (similar to those used in the VEX Robotics fields), purchased from a hardware store, and cutting them out with a holesaw. This is a multi-step process that generates a very large mess, but might be your only option. I used this technique on Thwackintosh and Blastwave_III