Scrap Gumball Machine

The project was to create a gumball machine out of materials available at home.

Materials Used:

• Gelato container
• Cardboard boxes
• Tape
• Acrylic paint
• Screw lid
• Top Coat
• Wooden skewer

This was originally my manufacturing project (cancelled due to the virus), and the design that was followed was using the youtube video below:

Since this diy project had to be scaled down, there were modifications made to the design shown in the video.

I started off by finding a container to fit the sizings of the rest of the mechanism against. I chose to use a gelato container because it was the largest clear container with a lid that I had.

First, I had to cut out the bottom of the gelato container. The plastic was too hard to cut using a box cutter, so I had to hammer in a square awl around the circumference until the plastic was cut out. Although this worked, it produced very jagged and sharp edges that could not be filed down with the tools I had. Therefore, I resorted to duct taping the edges to prevent injuries.

I decided to use the top of the gelato container as a tray to hold the container. I used a box cutter to cut the top, which was made out of hdpe and very easy to cut.

Next, I created the part shown below using cardboard. I was not too sure what its function was until I assembled the whole machine and realized that it was to stop gumballs from continuously falling into the hole and out the chute when the hole was aligned with the chute exit.

I used layers of cardboard to make the disk that carries the gumball. The edges of the cardboard were fuzzy and coming apart, so I sanded them down and coated them using a nail top coat.

I noticed that to hold all of these layers of cardboard, the tray had to be deeper. Therefore, I used scrap cardboard to add height to the tray.

I then initially put the parts together to observe how they move together.

To rotate this using a mechanism, I needed a gear system. I cut out another disk and used hot glue to attach a total of 18 teeth. I then wanted one rotation of the spur gear to rotate the disk a third, so I created a spur gear with 6 teeth. I did not bother to measure the disk or spur gear teeth location and size too accurately, and just hoped it would turn our more or less okay.

Next, I created a chute for the gumball to fall. I made it a right angle chute to make it easier to make, but realized I had to add a slanted piece inside in order to force the gumball to roll out of the chute.

I then cut out cardboard to start making the base where all of the components would be assembled. I hot glued a rectangularly scored sheet of cardboard around a circular piece that I cut to fit the opening of the tray. As I put together some of the parts to see how they work, I realized that the chute has to have a smaller opening in order to accommodate the mechanism that will turn the disk (marked in green).

I then attached the spur gear to a square-shaped rod that I created out of cardboard and passed it through a lid of a different container. However, I realized that with the current setup, the rod droops downwards because the only point of contact for the rod is the hole through which the rod is passed through, since the inside is hollow. Therefore, I added a cardboard piece to hold the rod up properly.

However, I noticed that the gear can still move around. Therefore, in order to limit its movement, I added a small rod to pass through the gear rod to hold it axially. This worked well, as the gear rod was hollow inside. It was still difficult to attach after I had already fixed the rod however.

I then tested out whether the gear mechanism works. Although it got stuck every once in a while, given that I took very few measurements, it worked much better than I expected. For every full rotation of the spur gear (when the part marked "top" makes a full 360), the disk more or less rotates a third, starting from a closed position and ending at a closed position.

As I was testing the machine out, I noticed that for the "gumball" size I have, the disk holes were too deep and therefore allowed two "gumballs" to go into a single hole. However, this caused a problem when turning the disk because the second top "gumball" would poke above the hole and get caught on the cardboard above it as the disk tries to turn.

Another mistake I noticed was that I had placed a tooth at the center of both the closed part and open holes of the disk. Therefore, when the spur gear turned the disk, the disk stopped slightly offset from the center of the closed portion or the open hole. I should have aligned the center with a gap between the teeth.

I decided to finish off the project by decorating the exterior with paper and covering up gaps. I realized that the weight of the paper balls acting as gumballs made the gears stall, and therefore in order for the system to function better I would need to invest more time in strengthening the gears. Now that I understand a lot of what needs to go in the design, I will try and remake this with a better plan in the future.