I am designing a pachinko ball dispenser that will dump 30 balls into a container for the machine flipper supply tray. I've been busy for a couple hours trying to discover a way to feed balls one at a time out of a supply hopper filled with potentially hundreds of balls. It sounds easy enough, but it's a rather difficult problem.

In order for my project to work, the balls simply MUST flow single file.

I started off my experiments by pouring about 100 balls into an empty water bottle dispenser and trying to dump them out. The balls jam together or "bottleneck" and won't naturally flow.
Then I used a cardboard box, and cut a hole a bit bigger than a ball. Same problem.
I cut a bigger hole, maybe 2" square in the bottom of the box and made a long tapered chute out the bottom. The bottleneck jamming was worse.
Then I cut a piece of 1/2" PVC pipe in half, and cut a long slot in the bottom of the box and put the PVC pipe underneath it so the balls would roll out. Same problem.
I took a piece of 2" PVC pipe with an elbow on it, thinking the elbow would effect the balls to work. I even put a long tapered trough on the end. But the problem persists.
I looked at the supply hopper in my Nichijin "A" to see how they do it. The balls flow down a tapered trough. I tried to duplicate the design in wax coated cardboard. Still the same jamming problem.

You can see my attempt to simulate the Nichijin hopper with its graduated trough in the photo below. Also the pipe and and representation of the 1/2 cut PVC experiment.

IMG_2378.jpg IMG_2379.jpg IMG_2380.jpg IMG_2381.jpg

The cardboard box shown with the cardboard taped underneath seemed to have the most potential, but they still somewhat jammed.
If I can discover a good reliable design I'll use more permanent materials.

I've given up for the moment and wondered if anyone here have tried to work that problem of getting balls to flow single file out of a hopper.
It's probably a simple solution but I have yet to discover it.