[Gary Dillard]

I'll answer the second question first....

I don't think running direct off of the keyang will give you enough velocity. Assume it runs pretty close to no-load speed (probably a pretty good assumption for what you're doing). Then the maximum velocity you can impart to the ball from the PVC is 80 rev/min * (pi*3.25) in/rev * 1min/60 sec = 13.6 in/sec. The rest is a projectile problem; horizontal distance traveled (X) is 13.6 * t, and vertical drop (Y) is (1/2)gt^2, so your vertical drop is (1/2)*386.4 in/sec^2*(X/13.6 sec)^2. That makes your vertical drop roughly equal to the horizontal distance squared, so if you are 6 inches away the ball will drop 36 inches. Note that just by changing the gear reduction to 2:1your drop will be only 9 inches.

As far as mounting the to keyang coupler, if you are using PVC you could use a PVC Cap and use the 4 existing holes to bolt through. Otherwise I think the wooden plug should work OK as long as there isn't too much slop in it; wood tends to tear up with cyclic loading.