Useless Easter Egg Machine

I put together a Useless Easter Egg Machine which incorporates electronics, art and DIY into one package. It was inspired by the Useless Machine kit from Solarbotics . I found this big egg full of candy that looked like it would be just about the right size for a useless egg contraption.  After consuming mass quantities of M&M's and Skittles, I began making my Useless Egg Machine before my sugar high could subside.

These are the supplies you will need:

Materials:

1. An Easter Egg (sans Candy!)
2. Micro Servo motor (I got mine from adafruit )
3. DPDT Submini Toggle Switch
4. Snap Action Switch (for use as the limit switch)
5. 2 - AA Battery Holder
6. 1/8” - 1/4" plywood, masonite, or similar
7. 1x2 piece of wood
8. Assorted Wire (about 18-20 gauge)
9. Small screws
10. Mod-Podge
11. Colorful, Vibrant Tissue
12. Yellow Chicken Feathers
13. Rubber Cement
14. Solder
15. Easter Basket and Grass
16. Small Paintbrush

Step 1: Tools

Tools:

1. Tiny, Eyeglass-repair type Screwdriver
2. Soldering Iron
3. Circular or Table saw
4. Scroll Saw
5. Wire Strippers/Cutter
6. Drill with 1/16", 3/8" Bits
7. Scissors
8. Glue Gun
9. Safety Glasses – “Before using any power tools let's take a moment to talk about shop safety. Be sure to read, understand, and follow all the safety rules that come with your power tools. Knowing how to use your power tools properly will greatly reduce the risk of personal injury. And remember, there is no more important rule than to wear these, safety glasses.” - Norm Abram

Other:
1. Pattern for cutting out arm and Servo bracket
2. Wiring Diagram for switches

Step 2: Decoupage!

First you have to decorate the egg since one half of the egg is clear. A useless machine is even more useless if you know it’s useless before finding out its useless. In order to disguise the uselessness of my egg, I decided to cover my egg with Decoupage! You could also try to paint it, put stickers on it, use glitter or mirror tiles... the sky's the limit!

Before starting with the decoupage, you will have to make a “hinge” so that the egg can open and close. Just take some sturdy packing tape and stick it on so that the egg opens and closes nicely.  

Now we can start decorating.

To decoupage, you’ll need some Mod-Podge, some vibrant, colorful tissue (or you could use Easter-themed prints, comics, clip art, etc…), a paintbrush and the egg. This is really easy to do, you don’t even have to be neat or artistic. 

Just brush on some Mod-Podge, tear some tissue, and apply it.

Brush on some more Mod-Podge over the top of it, really saturate it, and don’t try to smooth out all the wrinkles, the wrinkles add character (at least that is what I keep telling myself in my old age!)

Just keep layering the tissue over the top of the next. You will see it gives a stained-glass look to it.

When you are done, let it dry. If you don’t like the way it looks, you can always add more layers to it.

Step 3: Cutting Out the Parts

While waiting for the decoupage to dry, let’s start cutting out the pieces we’ll need for the project. I have made a PDF of the arm, the servo bracket and the base. Just print out the PDF. 

Use rubber cement to affix the patterns to the 1/4” plywood. This is the template you will use to cut them out with.

Before cutting them on the scroll saw, drill the holes first. This is easier done now, trying to drill the holes later is difficult with such small parts.

Drill a hole in the servo bracket “rectangle” that is of a big enough diameter that you can put the scroll saw blade thru it.  You could also use wood chisels to cut it out, like you're making a mortise.

Now cut out the pattern on the scroll saw, going a little bit outside the lines, you can always sand them later.

When finished, sand the edges smooth.

To make the base, start with a piece of wood that is a lot longer than you will end up with. It is easier and safer to cut the groove with a big piece of wood instead of a small one.

To cut the groove, set your circular saw or table saw to about half the base’s thickness (about 3/8” deep).

Mark out where you will make the cuts on the piece of wood.

Cut the groove first, it needs to be as wide as your servo bracket is thick.  It will probably take two passes with your saw to get a 1/4” wide groove.

When done, test fit your servo bracket, if good, then cut the board to the 1 ¼” width.

Put together the base and the servo bracket with a little glue in the groove. (my groove ended up being fairly tight, so i didn't use glue).

The servo should be mounted before soldering the wires. 

Attach the flange from the servo to the arm with the tiny screws. Note the orientation.

Step 4: Wiring the Electronics

The electronics in this project are not too difficult. The most difficult part is to modify the servo motor for continuous rotation. There are plenty of sites out there (some here in instructables) that will help you with it. I believe that Solarbotics also has some that are already modified, but note that they might be of a different size than the one used here.

To hook up the wiring, look at the drawing I made of the hook-up. It’s pretty straight-forward.

Take the DPDT Toggle Switch and look at the back. There are six terminals to solder to.

First solder the jumper from bottom left to upper right.

The battery’s negative wire will also be soldered to the lower left terminal, so do them both at the same time.

You will need to solder wires on the Limit Switch’s outer terminals as shown. Note that the positive battery lead and the limit switch “bottom” lead will both be soldered to the upper left terminal on the toggle.

The servo motor will have two wires, a positive and a negative, which are really just forward and reverse rotation. Throw a battery in and try both ways and you can figure out where each one goes.

The toggle switch in one position will move clockwise and when you switch the toggle, it should reverse. When you switch on the Useless Machine, you want the toggle to be in the “up” position so that the arm can come out and push it down.

Even though the arm seems to be turning itself off when it pushes down on the toggle, it is actually reversing the direction of the servo. It is the limit switch that actually turns off the machine. 

See my video below of the test run.  If your movement is similar, then you're ready to proceed to the next step.

Once the machine is wired up and tested, its time to put all this together.

Step 5: Putting It All Together

Take the servo bracket and base with the servo motor and attach the arm to the servo with the screw in the middle.

The arm should be past the edge of the base.

Mount the limit switch to the base as shown.

The "elbow" of the arm should end up pressing the limit switch and shutting itself off.

Put the servo unit in the egg and test fit.

You will want to align the arm to about the middle of the egg.

Put a couple of screws thru the bottom into the base to secure the unit.

Mark out where the toggle switch hole should be cut. (It should be about 3/8” down from the edge of the egg).

Drill the hole for the toggle.

Take the nut and washer off the toggle and thread the toggle thru the hole and then add the washer and nut.
Tighten.

Put batteries in the battery pack and put inside egg.

Try it out. The arm should move around and open the egg, turn off the switch, retreat back into the egg, hit the limit switch and then shut off.

If you have problems with the arm jamming on the inside of the egg, add some cardboard with some packing tape as shown.  The paper will help the arm lift the egg so the arm can come out.

Now add the yellow feathers to the arm, carefully crafting it to look like a little chick arm.

I mounted my egg inside an Easter basket so it would look more "Eastery" and it also makes it more stable.

Mount a block of wood by screwing a couple of screws thru the egg and into the block.

You can hot glue the block inside the basket, then add some easter grass and some eggs.

Happy Easter!