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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!

I figured out an angle for the container to sit at, hoping to help the snacks to move toward the opening naturally.

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I ended up with these two triangles to cut out.

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I cut these pieces out on the bandsaw freehand.

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I matched the bottom faces, clamped them together then sanded the inclined faces to match.

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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.

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I marked a piece of PVC pipe to the correct length (interior height of the container) then cut it with my miter saw.

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I drew two corkscrew lines around the end of the pipe by twisting it while moving the marker downward.

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It was tricky, but I spun the pipe into the blade as it cut, trying to match the spiral like. It worked pretty well.

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It’s not a perfect cut, but the spiral opening is there.

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I cut out two flaps of styrene to act as propellors.

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These pieces fit into the slot I’d cut with a little work.

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I tested the overall width to the bottom of the container, then trimmed with scissors until it could spin freely.

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I added some CA glue to each side of the both flaps to hold them in place.

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Using the largest bit I had, I drilled out the excess flap material on the inside of the pipe.

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It needed enough clearance to accept a dowel rod.

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I drew the opening for a door using a straight edge.

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Then I cut this panel out with a cut off wheel on my Dremel tool.

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I made a mark on the bottom of the container the same distance from the sides as from the end.

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I drilled a hole, then sat the container onto the ramp. Using my ice pick, I transferred that hole to the ramp.

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I drilled the hole from the top, then drove a screw up from the bottom of the ramp.

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I also drilled a small hole in the center of the dowel rod.

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Adding on the container, I threaded the dowel around the protruding screw tip.

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I drove in a second screw to connect the container to the ramp.

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Then I tested the movement of the propellor on the post.

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Holding a scrap of acrylic over the door opening, I traced the area to cut out and the outer shape.

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I cut this out on the bandsaw.

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Using a heat cut and some needle nose pliers, I bent the acrylic to fit around the slight contour of the container.

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I made sure the aluminum door piece fit underneath the acrylic while shaping it.

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Then I drilled four holes through the acrylic and the container.

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These two pieces got connected with long rivets. Notice the aluminum piece is still in place to maintain spacing.

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I pushed door piece completely down and scribed a line to show the top edge.

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I used a block of wood to bend the aluminum 90˚ along that line.

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I also marked out the shape of a pull tab for the door.

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I cut this tab shape out on the bandsaw.

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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.

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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.

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I drilled a hole in the end that matched the size of the post on the stepper motor.

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It was a pressure fit, nice and tight.

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With the propeller in place, I marked it’s location roughly on the container lid and drilled a hole at that spot.

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I pushed the stepper through the lid, into the propeller and traced it’s outline.

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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.

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Then I closed up the container, inserting the stepper stem into the propeller.

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I opened the door to it’s maximum and held the micro switch in place, with the switch compressed.

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I marked the location for the holes in the switch, then drilled them out with a small bit.

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I used two plastic automotive rivets, dropping the sleeve into the holes in the container.

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The posts of the rivets went through the switch, into the sleeves to secure the switch in place.

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Since this is pretty temporary, I  held the Arduino to the lid with some hot glue.

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I wired up the switch and tested that the door opening would consistently trigger it.

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Then I filled up the container with a snack and tested it out.

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It worked great! The propeller forces out the snack with ease!

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_YT_cereal