Roboto, the Wobbling Toy Robot (evolution of Randofo's "Wobbler")

I have a lot of broken toys on my workshop, so I decided to build a toy robot for Christmas. But I wanted to give it some attitude and more movement.

I found some inspiration in Randy Sarafan's Wobbler simple bot. I wanted my robot to wobble when it moves. But I changed some things from the original design:

• Two servos are too many for a robot that only moves forward. Besides, bringing servos to Azerbaijan is expensive (the local electronics store doesn't sell servomotors). But I have gearboxes from broken electric Chinese toys (you can buy new Chinese toys for $3 USD, or get them for free form your destructive nephews).
• I didn't want to work with 4 AA batteries, but only with 2.
• I wanted my robot to have arms with movement.
• I wanted my robot to look more like a commercial toy robot. You know, the kind of gift you can give to a kid.

So I created this project. I named it "Roboto", not because I'm lacking of originality, but because coincidentally it has a similar color palette to Roboto, one of my favorite characters from "He-Man and the Masters of The Universe" (I swear upon my cat Cringer it was just a coincidence).

Step 1: Materials

• Motor with gearbox (more information on the next step)
• cap from a deodorant (I used from "Garnier Men")
• Set of metal axle and wheels (from a broken toy)
• Toy case with switch and 2 AA batteries holder (from another toy, a broken toy robot, exactly)
• Iron angle
• 2 small rods from a broken umbrella (the small ones with a hole on each end)
• 4 brass pins
• 2 big (red) bottle caps (from 8 lt water big carafe of water).
• 2 small (blue) bottle caps (from any small water bottle)
• Toy pieces for the arms (I used from toy guns, more or less like this one. The arms of the robot were made with the barrels of some guns; and the fingers, with the triggers. Yes, I know, I'm a junk hoarder).
• Screws, nuts and iron washers.
• 2 small plastic beads
• Wires
• 2 AA batteries.
• Extra pieces from broken toys are always useful.

TOOLS:

• Dremel rotary tool
• Hot glue gun
• Soldering iron
• Screwdrivers
• Pliers

Step 2: Hacking the Gearbox

I used a gearbox from a toy (more exactly, from a bubble gun, like this one). In this previous instructable, I showed more in depth how to transform a bubble gun into a gearbox for robotic projects. For things of live, I have more access to broken bubble guns than to servos. Now, if you don't feel in mood of getting bubble guns and destroy them, you can get this 3V gearbox, and use one or two for this project. You will need to adapt some things, before passing to the next step, but nothing a hot glue gun a some creativity can't solve.

Basically, I removed the cover from the bubble gun gearbox and found the pump gear. I attached the metal rod (from a set of axis and wheels from a toy car) to that pump wheel, and then I drilled on each side to allow the metal rod to pass through the cover. I closed the case of the gear box and tested it passing 3V electricity to the motor pins.

Step 3: Wobbling Wheels

Using the hot glue gun, I glued the toy wheels to the red big caps. Not in the center, but close to the border. For extra reinforcement, I attached two small screws on each one.

Then, I inserted the wheels on the axle of the gearbox, not symmetrically, but opposite (one facing up, the other one facing down) so the robot can have the wobbling effect.

Step 4: Before Continuing...

I like to organize the pieces on the ground, before assembling. This gives me the idea of how the robot will look, if there is any extra piece I need to find, or maybe, if the robot will work/look better with other materials.

Step 5: Arms

Using toy pieces, I created two arms with claws, one for each side of the robot.

In case you can get specifically this kind of toy pieces, craft sticks or beams from building sets will do the trick.

Step 6: Joining the "legs" to the "body"

I drilled a hole on the toy's case/batteries holder, to attach an iron angle, where I would attach the top of the gear box (remember: this gear box comes from a bubbles gun. This "top" used to be the blower's mouth). I used screws, bolts and washers.

I checked the screw to not interfere with the batteries, and then I checked the robot can stand alone.

Step 7: Back Wheels

To keep the robot standing up and rolling without difficulties, I added some back wheels, using a metal rod (from a toy) and two beads. I placed them in a hole on the back part of the gear box.

Step 8: Shoulders

I drilled a hole on the center of each bottle cap, a hole on each arm and a hole on each side of the robot's body. Then I attached the arms and the caps to the body, using screws and nuts, leaving them loose enough for free up and down movement (you will see why on next steps).

Step 9: Head

I took the deodorant cap and I drilled a hole in the center. Then I drilled another hole on top of the body, where I screwed the head to.

I took a red key from a toy (a keyboard) and glued it to the face of the robot, so it looks like a visor.

Step 10: I Got Your Back!

I connected one cable from the motor to the positive pole of the batteries holder. I connected the other cable to one of the pines of the switch, and I connected the center pin of the switch to the negative pole of the batteries holder. I placed the batteries and tested the robot to check it goes forward (if your robot doesn't go forward, change the polarity). I fixed the connections with the soldering iron.

I put a plastic piece from a mouse, to cover the back.

Step 11: Transmitting Movement to the Arms

I drilled a small hole (big enough to fit a brass pin) in the arm and wheel of each side of the robot. Hole on the wheels of the robot must be alternate, as the same way of the ways, in order to give alternate movement to the arms.

Then I took the small umbrella rods. On the hole of each end, I placed a brass pin. One of the end goes to the arm; the other, to the wheel. I needed to put a drop of superglue on the tip of the pins to keep them in position, but carefully to avoid jamming the mechanism. The umbrella rods must move loose on the pins.

After testing and solving some minor details, finally I got my toy robot ready!