FRC3548 4 wheel Ball Shooter

[MrForbes]

We're pretty darn lazy, and it seems to take us forever to make just a single moving part for the robot. So we just used one motor, one wheel, one gear, and let the ball get a lot of back spin, which conveniently makes it like to go into the basket when shot at the backboard.

http://www.youtube.com/watch?v=81vOT2KY2ig

So to answer the percent spin difference question...we "spin" the upper "wheels" at zero speed (it's just a couple pieces of metal, not wheels). and spin the lower wheel at about 3500-4000 rpm.