Hi all,

I'm a mentor for a local high-school's robotics program, participating in the FIRST robotics competions, and I'm new to their team, as the previous mentor moved out of town. I'm really an electronics engineer, but I do have experience with many things mechanical (RC aircraft, cars, my CNC tinkerings, etc).

After some issues with our robot in a competition last week, we need to re-engineer parts of it quickly for another competition in 3 weeks. And since this will be the last competition with this robot, and we need to keep costs down, I want to re-engineer as little as possible to meet the end goal. Hoping someone here can assist me quickly with some opinions on my proposed changes, as I need to order parts fast.

The drawing below shows the current setup on the left -- a vertical arm in a tower which is pulled upwards by rubber bands, and triggered/released by a pneumatic actuator. The vertical arm is supposed to hit a large ball (>4ft dia) supported on some overhead rails. The arm can't be higher than the rails (so the robot can pass under), but we're finding that even though we can brush against the bottom of the ball, it's not knocking it off.

So the redesign (sketch on right) is to use the same arm, and power the arm so it can go up and back down. This way we can get the vertical arm higher to properly knock off the ball, then down to clear the horizontal rails.

Questions...
- Should I use a timing belts or a Vee-belts? I would thing Vee, since any resistance/force on the arm (another robot, etc) would just make it slip, rather than break.
- Is there some thing I can "crimp" or fasten to the belt so that it can easily be secured the dowel for the vertical arm? Or is it acceptable to clamp down on the belt with some screws etc (perhaps with a plate so the screws don't cut the belt)?
- Any better/simpler/quicker options?

Thanks,
-Neil.