The CMH BristleBot

Build your own pet "robot!"

This is one of the 48 projects for our Instructables: Made In Your Mind (IMIYM) exhibition at the Children’s Museum of Houston showing from May 26, 2012 - November 4, 2012. Produced in partnership with Instructables, IMIYM is an exhibit where families work together to build different fun, toy-like projects that help construct knowledge and skills related to science, technology, engineering, and mathematics while instilling a “do-it-yourself” attitude in kids so they feel empowered to explore, tinker, and try to make things themselves. To learn more, check out the article here.

There are lots of BristleBot designs on Instructables (the first one that came up in our initial search was the How to Make a Pocket-Sized BristleBotby kill1234). However, the one featured here we made specifically for use in the Museum. Often, the materials and process for building our projects are designed for use with a large number of visitors (we see over 800,000 annually) and the need to ensure safety in a mostly non-facilitated environment. So, yes, many of these projects have room for improvement in both materials and methodology, which is PRECISELY what we want to encourage the kids to do. So please do share your ideas for improvement and modifications!

Step 1: Materials

We are selective in our materials for cost, ease of use, and safety due to our high traffic (800,000 visitors annually). So, for our purposes, this design worked best. But you may have other ideas - please share!

1 - Fingernail brush we purchased them in bulk from Amazon, but you can get much more colorful ones at beauty shops or megalowmarts (Walmart, Target, K-Mart, etc.). The motor below is strong enough to move larger brushes, too.
1 - CR2032 Coin Battery - we get our in bulk from Batteries and Butter
1 - Pancake Vibrating Motor - this was a real find for us from All Electronics - it has a self-adhesive back and two leads already attached
1 - 1” double-sided foam tape
1 - Pipe cleaner
Scissors
Masking Tape
Ruler

Step 2: The Video

We offer optional video segments of each step for this project in the actual exhibit. Here is a compilation of all the steps.

Step 3: Step 1

The fingernail brush we use is a little too narrow and tends to tip over when moving, so we adding in stabilizers. To start, cut the Pipe Cleaner into four 3” pieces.

Step 4: Step 2

Bend one piece in half and place it over one end of the brush. Tape it in place.

Step 5: Step 3

Bend the ends off to the sides of the brush to create “feet.”

Step 6: Step 4

Repeat steps 2-3 at the other end of the brush.

Step 7: Step 5

Since you don't really need all the pipe cleaner to make feet, as an option, you can use the other two pieces of pipe cleaner to create ears (or horns - we are in Texas, after all) and a tail.

Step 8: Step 6

Remove the paper backing from one side of the double-sided foam tape. Stick the tape to the top of inside edge of a handle. Do not remove the other paper backing, yet.

Step 9: Step 7

While the leads to the motor come very slighly exposed, it really isn't enough to work well. So, you need to strip the wires a bit more, but the lead are VERY small and VERY delicate. Using the edge of the scissors, GENTLY scrape away about 1/8” of the rubber insulation from both leads.

Step 10: Step 8

Peel off the backing from the motor and stick it to the inside edge of the handle opposite from the foam tape.

Step 11: Step 9

Remove backing from the foam tape and press the one of the wires into the center of the tape so it just sticks. Keep the other wire off the foam tape.

Step 12: Step 10

Stick the battery onto the tape over the exposed wire with the positive (“+”) side facing up.

Step 13: To Use

To turn on your BristleBot, tape the free wire to the “+” side of the battery. To turn it off, remove the wire.

The vibrations that make the BristleBot move are created by the pancake motor, which is a type of offset motor, the same type of motor that makes some cell phones vibrate. Inside the casing is a spinning disk with a weight on a small part of the disk. As the motor spins, the inertia of the spinning weight pulls the motor in different directions, causing it to vibrate. Because the motor is attached to the brush, the vibrations are transferred to the brush, making it move. Placement of the motor and how the BristleBot is weighted will affect how it moves. Flipping the battery will cause the motor to spin the opposite direction which may also affect the movement of the BristleBot.

BTW - this is NOT a robot. A robot actually takes information in from its environment, processes it, and responds with a specific output. This is just a fun toy that spins around.