My daughter was about nine years old when she wanted a gumball machine. I decided I could make one from wooden parts and an old pickle jar. At the time, there were some cheap gumball machines for children that dispensed a gumball when a large dowel was rotated. There was no coin-operated mechanism. My daughter wanted to be sure to charge her brother and her sister for all gumballs they consumed, so the coin-operated feature was a requirement.
(The photo is from Bing Images.)
Step 1: My Mechanism and How It Works
(Note: The photos were added much later. The drawings were done from memory. There is a discrepancy. The drawings show the indent step in the wrong place. Reverse the location of the indent to make it on the opposite end. Compare the photos.)
This is the slider mechanism for the gumball machine I made. It is my own design. The two main parts are designated as "A" and "B." In summary, a coin is inserted through a slot from above (not shown.) and its edges fit into the recesses marked as "D." The operator pushes on the left end of "A." The coin pushes on "B" and moves it forward. The gumball loaded in hole "C" from an inverted glass jar above is pushed until it aligns with another hole below in the frame of the gumball machine (not shown), and the gumball rolls down a channel (not shown) to fall into a cup on the exterior of the machine (not shown). When the operator begins to pull the slide "A" back to its original position, the pressure on the edges of the coin is released and it falls through a slot below into a coin box (slot and coin box not shown). Part "F" is a piece of bent wire. It slides in the recessed channels and round holes indicated by the two "E"s. "F" engages "B" when "A" begins to be pulled back to its original position. This also pulls "B" back to its original position so a new gumball can fall into hole "C" from the jar above. Although shown too small in the graphic, the round holes that are part of the inletting for "E" on each piece are a large enough diameter that if someone pushes "A" without a coin in the machine, "A" moves harmlessly inward, but "B" does not move forward and no gumball is dispensed. Make the round holes in "E" larger in actuality. There is enough tension on "B" supplied by a light spring from below that it does not slide when the machine is tipped. "G" is a recess in the side of "A" that rides over a vertical pin set to limit the travel of "A" so it can neither be pushed inward too far, nor pulled out of the machine.
"A" and "B" are made from a good, but inexpensive close-grained and easily-worked hardwood. The thicker end of "B" is as thick as the diameter of the gumballs you will be using plus just a little bit more, perhaps a little less than 1/16 of an inch. The hole marked "C" should be just slightly larger in diameter than the largest gumball in any package of the type you buy and use.
The photo shows the actual machine I made. I was able to get it from my daughter and take actual dimensions. I am working on these photos from an iPad and I am forced to use text notes, which make precision difficult. Check for pictures in other steps and dimensional information to get a complete set of measurements.
Step 2: Another Explanation of the Mechanism
This is a view of the mechanism operating in its various steps and conditions. The first graphic shows a coin in place (thin black rectangle) The sliders "A" and "B" will travel from left to right. Notice the position of the wire (red) in the inletted holes (gray). It is just a little loose in the holes, but not much. The blue dotted line represents the change in thickness cut into the "B" slider. The green circle is a gumball loaded in the slider hole. The blue semi-circle is the hole to the channel where the gumball will be dispensed. Notice also the position of the black limiting pin for the "A" slider. The travel of the "A" slider is just a tiny bit more than the diameter of the coin.
In the second graphic the direction of travel has been reversed. The hole for the gumball shows a blue color to indicate the gumball has fallen down the channel. The coin is no longer visible and has fallen into the coin box. The limiting pin is now in the position to keep the "A" slider from moving any farther into the machine. The wire (red) is firmly pulling the "B" slider backward in tandem with the "A" slider.
The third graphic shows what happens if someone tries to get a gumball without inserting a coin. The "A" slider has moved inward as far as it can go. The Limit Pin is against the shoulder of the "A" slider. The wire (red) is loose and does not push on the "B" slider. The green gumball remains unmoved.
Step 3: Select a Glass Jar
Choose a glass jar about one quart in size. It should have a good sturdy metal lid. A one-piece metal lid would be preferred, but a two-piece lid from a standard home canning jar could work.
Make a hole in the center of the lid large enough to pass a gumball. Make a wooden disc 3/4 inch thick and just a tiny bit less than the diameter of the jar's opening. Chisel by hand or turn the wooden disc on a lathe so one surface forms a cone like a funnel to help feed the gumballs into the gumball machine. Make a hole in the center of the wooden disc to match the hole in the metal lid. Set the jar and the disc aside for now.
(The photo is from Bing Images.)
Step 4: Starting the Works
Begin by cutting a piece of Masonite the size of the machine's base. This could be about 4 1/2 x 6 1/2 inches. The hole is for the gumballs to fall down into a channel so they can roll to a cup on the side of the machine. The slot is for the coin to fall down into a coin box. Notice that both are closer to the back edge of the machine than the front. It is impossible to give exact dimenions because those will depend on the gumballs and the coin you use.
Step 5: The Next Step
The red arrow indicates the width of sliders "A" and "B" from step 1. Add two pieces of hardwood to the Masonite piece and glue them in place. Their thickness should be equal to the thickest part of "B" in step 1, which is the diameter of the gumballs.
Step 6: Add a Spacer
If you remember the description of how the mechanism works from step 1, "A" was only the thickness of the coin used. If the coin is smaller in diameter than the gumball, a spacer needs to be added. The red arrow indicates the diameter of the coin. When the slider mechanism is fully pulled back ready for another coin, the step on part "B" will rest against the part of the spacer nearest the hole for the gumball.
A flat spring or part of a common safety pin could be added so it presses lightly against the "B" slider to guarantee that it does not move due to gravity, if the machine is tipped.
Step 7: Make and Fit the Moving Parts
Make and fit the moving parts. The position of the holes for "E" in each piece is not critical. What is critical is the bends in the wire "F." Position "A" and "B" so the coin fits just a little loosely in "D." Bend "F" on both ends so one end is snugly against the right edge of the hole in "A" while also snugly against the left edge of the hole in "B." Position and set the vertical limiting pin for "G" so the mechanism performs as it should. The width of "G" is a little more than the diameter of the coin plus the thickness of the pin.
Step 8: Make a Top Cover
Place the moving parts into the assembly prepared for them in steps 4 through 6. Cut another piece of Masonite to fit over the assembly. With the moving parts pulled fully back as if ready to insert a coin before dispensing a gumball, mark the position of the coin slot and the gumball hole in "B" onto the top piece. Cut both. Attach the top piece with screws.
Position the jar lid and the wooden disc so both align with the gumball hole. Drill and screw so the screws go into the solid pieces of wood on either side of the moving parts. Add a knob to the outer end of the "A" slider.
Step 9: Add a Base
Add a skirt for a base to the assembly with the moving parts. (The view is from the underside.) The protrusion is the "A" slider fully retracted and ready for a coin to be inserted. The hole in the graphic is where the gumballs drop down.
Step 10: Make a Channel for the Gumballs
The channel that carries the gumballs can be made of almost anything. The graphic shows a piece of 1 1/2 inch stock scalloped out to make a half-pipe. Miter the ends to fit and mark the location for a hole in the side of the machine. Drill the hole. Glue the channel in place. Fashion a metal catch cup from sheet aluminum and use brads to fasten it to the side of the machine.
Step 11: Make a Cover for the Bottom
Add some feet to the machine, if desired. Finish it according to your preferences.
Fill the jar with gumballs and let the kids play. This gumball machine makes a fun bank.
Obviously, the kids can unscrew the jar from the top of the machine and take gumballs without inserting coins. But, that takes all of the fun out of using the gumball machine. The one problem we had with this gumball machine is that the balls did not always feed into the hole on top of the machine as they should. We often had to shake the machine to get a gumball to feed properly. Perhaps a larger hole in the jar lid and wooden disc would have helped.
I no longer have access to this gumball machine. That is why I used graphics rather than photos to describe its construction, and that is why I cannot show a photo of the finished gumball machine.