Unsolved problem: How to prevent jamming in a ping pong ball hopper?

[LCHIEN]

Started working on a ping pong ball hopper for my son in law. But I'm running into issues of the storage bin feeding down to a single outlet where two balls will meet and jam. My picture below. Manufacturing conveyers do it with vibrators but that is not practical for a game room.

This reddit post (not mine) describes my problem exactly:

Prevent clogging of a ball-filled hopper

I'm working on a project that consists of a hopper (funnel-shaped with a cylinder on top) which holds about 50 ping pong balls (40mm diameter). They are supposed to flow out through a tube at the bottom (currently 42mm in diameter). Does anyone know if there are rules how to design something like this to allow the balls to flow out smoothly without clogging up? I'm specifically looking for the best angle of the funnel and if there are any 'critical' dimensions to avoid (i.e. a multiple of the ball diameter?).

[Nick Keenan]

When your chute narrows from more than two balls wide to less than two balls wide, there is a point where it is exactly two balls wide. If two balls arrive at that point at the same time they will get stuck. Since the chute is narrowing the sides won't be parallel with each other, the sides will exert some horizontal and upward force on the balls. Making the sides steeper helps but there's no way to eliminate the possibility of sticking.

If the chute is never more than two balls wide then you won't get stuck. Or if you set up some sort of mechanical device to keep two balls from arriving at the same time. Sometimes you'll see a pendulum-like device that swings one way when a ball arrives from one direction, and then swings back when another comes. The problem is ping pong balls aren't that heavy, the device would have to be super light.

[LCHIEN]

thanks for your comments.

[leehljp]

I have been thinking and thinking on this but cannot come up with a specific answer. If I had time and an organized (cleaned out) shop, I think I would try making one and experimenting with different angles and spacers and openings on another upper arm. While not like a expressway/interstate method of lining vehicles up by forcing all to a right lane for a mile and then switching everyone to the left lane - there probably is a method of getting all to line up BEFORE the clogging portion of the lane.

[LCHIEN]

I've been working on this for a year... I don't think there is a solution that doesn't involve active vibrator/mixer mechanisms, there will always be an angle where merging the balls will come together come to a junction no matter what angles there are and their alignment will jam.
I'm thinking the alternate is a series of parallel channels, you can pick up the ball from any channel and a ball will drop down and replace it... You still load from the top and the balls will fall naturally into one of the channels.... splitting is easy but merging is not.

[dbhost]

I am thinking short ramp above the jam point that will only allow one ball, angle that short ramp so that it feeds onto the lower ramp maybe? (I am pulling ideas out of thin air here, sorry).

[d_meister]

56 years ago, I went to the Museum of Science and Industry near the USC campus often to fire the rocket engine and watch the ping pong ball drop that demonstrated statistical probability. There were hundreds of balls dropped from above a clear acrylic box with an interior a little more than one ping pong ball wide. Like an ant farm for ping pong balls. I think the thing might have been a Galton Board on a huge scale, maybe 4' x 8'. Looking at a Galton board, https://galtonboard.com/video, and remembering the display, the balls were diffused by dozens of pegs that had the balls rattling and bouncing all over until resting in a statistical curve at the bottom. Three take-aways is that the balls could be funneled from the center, that their travel be randomly slowed by peg obstacles when fed into the device, and that the ramps should have little more clearance than maybe 1.5 x the diameter of the balls on the Y and Z axis.

[LCHIEN]

Galtonboard... Now that's interesting. THat's how Pachinko machines don't jam. I need to think about that some.

[capncarl]

Considering the weight of ping pong balls maybe an air blast may keep the balls moving.

[Nick Keenan]

Considering the weight of ping pong balls maybe an air blast may keep the balls moving.

Or to take a ball out you have to open a door, the door is connected to an agitator that rattles them a bit.