[fox46]

Here is what I would do: I would abandon the chain idea and try to drive the sprocket like it was a gear. Take a small segment of #25 chain and then wrap it around a flanged hub of some sort, securing the ends to the flange of the hub with a pair of pins. Basically, this provides you with a "pinion gear" to install on your drive motor and power your "sprocket gear". You mentioned the #25 chain engages the sprocket fine in small intervals so driving it like a gear would only mean you are contacting the sprocket along two or three teeth.

Generating an accurate CAD model for something like this is always a pain in the @$$. Last year it took us about 15 tries to finally produce a working sprocket for our drivetrain despite using the FIRST CAD library. I assume that at this stage of the game the chances of you getting a new sprocket cut in time is slim to nil.

A wire wheel is a disc that you would install on a pedestal grinder that looks like this: http://www.wolfcraft.us/images/photo...eWheel-8In.jpg
It is used for cleaning up parts and removing small amounts of material. I remember trying this last year when my team was trying to produce their own sprockets and if you are off by much it won't work and I wouldnt suggest it.