Servo - March 2014

With that in mind, I set about reverse engineering the tracks and sprockets to make a set of 3D models available to hobbyists. Most of these models are available on www.teamrollingthunder.com website under "Solid Models."

Keep in mind that tracks don’t necessarily give an advantage over wheels in combat robotics, but they do look cool! Plus, the Pololu tracks and sprockets should be tough enough to survive most hits from smaller bots.

First, I created the standard 22T and 30T track sets (Figures 5 and 6) with the standard 12T sprockets, shoulder screws, washers, etc. You can use these to create different arrangements like the four motor/six sprocket arrangement in Figure 7. It should have plenty of power for an Antweight.

Alternatively, one could use two of the Finger Tech Silver Spark motors instead of the four smaller motors, or two of the smaller motors in a weaponed bot. I don't think anyone has built a tracked drum bot yet.

Next, I looked at making different sized sprockets and even tracks using a 3D printer. Creating the model for a six-tooth sprocket and a 40-tooth track (Figure 8) was easy enough once I had worked out the basic geometry.

The sprocket works well, apart from having to drill out the center hole as it was a little undersized. The track was made from an experimental elastomer and while it appears tough enough, it's a little too stiff to use with smaller sprockets.

WIth the different sizes of sprockets and tracks available, a whole new range of bot shapes becomes possible. How about a cheese wedge shaped Fairyweight that uses the 22T track, a standard 12T sprocket, and a 3D printed six-tooth sprocket? If you can imagine it, then it can probably be made.

The 6T sprocket and other 3D printed parts are available from www.shapeways.com (search for kitbots) and the standard parts from www.pololu.com. SV