I have been working on a ball bearing glockenspiel. The contraption will be comprised of 3 systems – ball bearing launcher, ball bearing collection and return mechanism, and the instrument itself.
I started with the the launcher. There will be 25-30 notes and a fast and accurate launcher will be needed for each one. My design parameters were to launch 4 bearings a second within a 1/2 inch diameter over a 2 ft. drop. Here’s my first attempt.
A pipe feeds ball bearings to a rotating platform with a hole just large enough for one bearing. When it’s ready to drop, the servo rotates the platform by about 30 degrees and the bearing falls out the bottom. The platform then rotates back to the home position and loads the next ball. The mechanism could definitely deliver the balls quickly but the accuracy just wasn’t there. The balls would hit the side of the hole as they were exiting. On to the next iteration…
I forgot to take a picture of this one so I am posting the drawings instead. The concept is the same as the previous version, except the slider is linear instead of rotary. I added a longer channel after the initial drop to guide the ball bearings as they fall. But I had the similar accuracy issues.
So, I kept iterating the design to minimize potential disturbances after the ball is launched. And of course, decided to use magnets. The bearing are made out of steel and magnets suspend the ball till a servo controlled “plunger” launches them. This design worked beautifully! I have attached two slow motion videos below. As you can see in the second video, it’s so accurate the balls are literally hitting each other like Robin Hood “splitting an arrow”!
Next, I will work on making this design more compact and also, several ball return mechanisms.