My kids are getting older. They’re getting old enough, in fact that they are starting to make their own breakfast! The other day, I came down for coffee to an entire family size box of Honey Nut Cheerios poured out (by accident) on the floor of our kitchen. Within days, someone named Marc left a comment on YouTube asking me to make an automatic cereal machine. It was a great idea, and very timely, so I figured I’d give it a shot.
As silly as it is, it was a lot of fun! The electrical stuff is very simple and the build was an interesting set of problems to solve. Check it out!
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- Arduino code on GitHub
- SawStop cabinet saw
- Dewalt 20v drill driver combo
- Pancake compressor/nail gun combo
- Grizzly G0555LANV Bandsaw
- Shop Fox Hanging Air Filter
- 2HP Dust Collector with 1 Micron bag
- Heat Gun
- Hot glue gun
- Rivet Gun
- CA Glue (medium)
- CA activator
- Speed square
- Arduino Uno Kit
- Soldering Iron
- Micro switch
- Motor shield
- Stepper Motor (NEMA 17)
- Wire strippers (not the ones I have, but good ones)
I figured out an angle for the container to sit at, hoping to help the snacks to move toward the opening naturally.
I ended up with these two triangles to cut out.
I cut these pieces out on the bandsaw freehand.
I matched the bottom faces, clamped them together then sanded the inclined faces to match.
I glued and nailed these to another rectangle to make a ramp. I replaced this whole piece later with a taller one which lifted the whole thing off of the table a bit. This allows a bowl to sit right in front of the opening.
I marked a piece of PVC pipe to the correct length (interior height of the container) then cut it with my miter saw.
I drew two corkscrew lines around the end of the pipe by twisting it while moving the marker downward.
It was tricky, but I spun the pipe into the blade as it cut, trying to match the spiral like. It worked pretty well.
It’s not a perfect cut, but the spiral opening is there.
I cut out two flaps of styrene to act as propellors.
These pieces fit into the slot I’d cut with a little work.
I tested the overall width to the bottom of the container, then trimmed with scissors until it could spin freely.
I added some CA glue to each side of the both flaps to hold them in place.
Using the largest bit I had, I drilled out the excess flap material on the inside of the pipe.
It needed enough clearance to accept a dowel rod.
I drew the opening for a door using a straight edge.
Then I cut this panel out with a cut off wheel on my Dremel tool.
I made a mark on the bottom of the container the same distance from the sides as from the end.
I drilled a hole, then sat the container onto the ramp. Using my ice pick, I transferred that hole to the ramp.
I drilled the hole from the top, then drove a screw up from the bottom of the ramp.
I also drilled a small hole in the center of the dowel rod.
Adding on the container, I threaded the dowel around the protruding screw tip.
I drove in a second screw to connect the container to the ramp.
Then I tested the movement of the propellor on the post.
Holding a scrap of acrylic over the door opening, I traced the area to cut out and the outer shape.
I cut this out on the bandsaw.
Using a heat cut and some needle nose pliers, I bent the acrylic to fit around the slight contour of the container.
I made sure the aluminum door piece fit underneath the acrylic while shaping it.
Then I drilled four holes through the acrylic and the container.
These two pieces got connected with long rivets. Notice the aluminum piece is still in place to maintain spacing.
I pushed door piece completely down and scribed a line to show the top edge.
I used a block of wood to bend the aluminum 90˚ along that line.
I also marked out the shape of a pull tab for the door.
I cut this tab shape out on the bandsaw.
Here are the electronics for this project. An Arduino Uno, motor shield, NEMA 17 stepper motor and a microswitch. It’s a very simple circuit. Code is linked above.
I cut a scrap of wood to fit tightly into the PVC pipe, covered it with CA glue then hammered it in with a mallet.
I drilled a hole in the end that matched the size of the post on the stepper motor.
It was a pressure fit, nice and tight.
With the propeller in place, I marked it’s location roughly on the container lid and drilled a hole at that spot.
I pushed the stepper through the lid, into the propeller and traced it’s outline.
Using this outline, I measured and drilled four holes to mount the stepper motor to the lid. I drove in small screws from the underside to secure it.
Then I closed up the container, inserting the stepper stem into the propeller.
I opened the door to it’s maximum and held the micro switch in place, with the switch compressed.
I marked the location for the holes in the switch, then drilled them out with a small bit.
I used two plastic automotive rivets, dropping the sleeve into the holes in the container.
The posts of the rivets went through the switch, into the sleeves to secure the switch in place.
Since this is pretty temporary, I held the Arduino to the lid with some hot glue.
I wired up the switch and tested that the door opening would consistently trigger it.
Then I filled up the container with a snack and tested it out.
It worked great! The propeller forces out the snack with ease!