Ping-Pong Ball Shooter

I've been powering this off my train regulator because I'm all out of batteries. I've been shooting the balls over 20 feet with the motor turned up to full speed. The hammer I think may need some redesigning, it tends to break apart after a few shots. It's spinning pretty fast, so it hits the balls pretty hard. For now I've wrapped rubberbands around the bricks on each end, and it seems to be holding together.

Construction notes:

There's supposed to be a large tire, like the large spoked one found in the mindstorms sets behind the motor, but I couldn't find that part. The large wheel acts as a flywheel, to keep the motor spinning when the hammer impacts the ping-pong ball.

The motor should be connected to the large pulley on the flywheel axle with a small white belt, and the hammer should be connected with a blue belt. The blue belt allows enough slip that when the hammer is completely stalled, the motor continues to spin, but is still tight enough that the hammer comes up to speed fairly quickly.

I'm still not sure if the flywheel is needed. It's difficult to tell if the motor is stalling or not, at least without hooking up some kind of RPM measuring device.

Click on the images to get the LDraw .dat files.