mating 2009 rover wheels and sprockets

[Andy Baker]

The holes in the 2007, 2008, and 2009 FIRST Wheels (aka: Rover Wheels) have a diameter of 0.17". The intention of this diameter is to use the hole as a pilot hole for a #10-32 or #10-24 or M5x0.8 screw. Some teams drilled out this hole to 0.20" and used a long #10 screw and a nut. While this is a secure way to fasten the sprocket, it is not needed.

As Greg correctly points out, you can tap the hole for a #10 screw. Alternatively, you can simply drive a #10 screw into the hole, even without tapping the hole. If you use a cordless driver, the heat of the screw cutting through the polycarbonate will actually melt the polycarbonate a bit, right around the screw end, and act as a very secure locking method. So... you don't have to use a tap to thread the hole.

Some FRC teams used "thread cutting" or "thread forming" screws. We have found a good one, that has a 5/16" hex head for easy driving, and we offer it here on the AndyMark site. This screw requires no tapping of the hole and it is very easy to drive.

Sincerely,
Andy Baker