A Simple and Cheap No-Solder Bristlebot!

UPDATE:

My new Instructable for an Artbot has a cheaper, updated design. This bristlebot design will stay up for posterity, but I wouldn't recommend it for a workshop anymore (plus the brush I used is no longer available from Dollar Tree).

This Bristlebot (or Brushbot) is easy to make and is made out of super affordable materials! I designed this to be used as part of a series of robotics workshops for LAPL on behalf of the Los Angeles Makerspace. While the Bristlebot isn't a true robot per se, it serves as a great introduction to electromechanics and electronic circuits, especially for a younger audience.

Step 1: Materials

These materials were found at dollar stores, retail stores, and radioshack. None of these parts are particularly essential, and can be swapped out for equivalent materials based on what is available to you (ex: hot glue instead of mounting tape, cork instead of rubber eraser). These are what I've found to be cost effective and easy to work with:

- x1 "Garage Brush" from Dollar Tree
- Scotch Extreme Mounting Tape
- Scotch Indoor Mounting Tape
- x1 2 AA battery holder
- x1 Paperclip
- x2 Thumbtacks
- x1 rubber eraser cut in half lengthwise
- x1 3V DC motor (A bit pricey at radioshack, I got mine from Sparkfun for about $1)

Optional Materials:
- Tape
- Glue
- Pipe cleaners
- Foam sheets
- GOOGLY EYES

Step 2: Mount the Motor

Attach about 1/4" of the extreme mounting tape to the side of the motor. Peel off the plastic backing. This was surprisingly difficult with the tape I used, just keep going at the edges and corners with your fingernails and try not to peel the tape off the motor too much. Position the motor carefully then stick it down to the brush. Be sure to position the motor far enough out so that the eccentric weight won't hit the brush or the bristles later.

Step 3: Mount the Battery Holder

Attach about 1" of the regular mounting tape to the back of the battery holder. Peel off the backing and stick the battery holder on the other side of the brush. Make sure there is enough space between the battery holder and the motor for one of the eraser halves.

Step 4: Mount the Eraser

Attach about 1/4" of the regular mounting tape to one of the erase halves. If the halves aren't perfectly identical pick the bigger half for this step. Peel off the backing and stick it to the brush right in the middle, between the battery holder and motor.

Step 5: Connect the Red Wires

Bring the red wire from the battery holder and the red wire from the motor together. Twist the two ends together tightly and neatly. I've stripped all my wires ahead of time with about an inch of exposed wire, but a little more would have been even better.

Step 6: Make the Paperclip Switch

Alright, this is the tricky step! Take one of the thumbtacks and wrap the exposed part of the black wire from the motor around the shaft of the thumbtack. Position the paperclip in the center of the eraser. Then, position the thumbtack so that it just touches the inside of the curve at the end of the paperclip. Push the thumbtack all the way down.

Take the other thumbtack and wrap the exposed part of the black wire from the battery holder around the shaft of the thumbtack. Position the thumbtack so that it just touches the outside of the curve at the other end of the paperclip. Push the thumbtack all the way down.

Open your switch by swinging the paperclip out from under the thumbtack connected to the battery holder. Phew!

Step 7: Test the Switch and Tidy Up

Put some batteries in the holder and make sure your switch works. Close the switch by sliding the paper clip back under the thumbtack connected to the battery holder. You should hear the motor start up. If you don't, it's troubleshooting time!

- Make sure the paperclip is securely beneath both of the thumbtacks. This will ensure when the motor vibrates the switch will stay closed and not get shaken open.

- Make sure the thumbtacks are pushed all the down so that the flat parts are in tight contact with the paperclip.

- Make sure the black wires are securely wrapped around the thumbtacks.

- Make sure your red wires are properly twisted together.

Once everything is confirmed working, tape down the loose wires to the brush. This step is optional, but recommended. It's also a good idea to tape the twisted red wire ends together so they don't come undone later. I've used bits of gaffers tape here, but any old tape will do.

Step 8: Add the Eccentric Weight

Get the other eraser half and poke a hole through it with a spare paperclip or thumbtack. Line this pilot hole up with the shaft of the motor and press the eraser on. This may require quite a bit of pressure. Experiment with the position of the eraser on the motor shaft! As you can see I found that the bristlebot worked better for me with the shaft more centered than in the first pictures. When the eraser was too off-center the bristlebot would just spin rather than travel in a straight-ish line.

Step 9: Give Your Bot Some Style!

You're all done! Now put some googly eyes on that bristlebot! I used hot glue to attach some pipe cleaners and foam sheets too, but tape or any quick setting contact adhesive should also work.
 

Congratulations on your awesome adorable bristlebot!