Step 1: Assembling the Robotics Breadboard - Part 1: Mechanical
Mechanical Parts List
Note: Digikey part numbers can be entered on their home page. Press GO and you'll go right to the part description.
1 Solderless Breadboard (Available from PJRC, Radio Shack, or Digikey 438-1045-ND)
2 Pololu Motors
1 Pololu Roller Ball (come in a pack of 3. Share with a friend or keep for spares.)
1 Battery box for 4 – AA Batteries (Digikey BC4AAW-ND; also try Frys, RadioShack, etc.)
1 Battery box for 2 – AA Batteries (Digikey BC22AAW-ND
2 Pipe Plugs (These become wheels) You can find these in the Plumbing department at Home Depot or a good hardware store. Pick a diameter you like. See the pictures below.
2 Large rubber bands (like on asparagus bundles). Could use multiple smaller ones also.
Let's start putting the pieces together. Picture 1 shows the front of a solderless breadboard. This will be the chassis for the robotics breadboard. We'll attach our motors, battery holders, and roller ball to this. If you don't already have a suitable one, some alternatives are in the Parts List.
The key mechanical component for a robot is the motor. Let's talk about motors for a minute before we get on with building. The Babuino is designed to control DC motors. The problem with DC motors is that they spin very fast. If their voltage is reduced enough to slow them down, then the power they have is greatly reduced. To reduce the output speed without reducing power, gears are used. A servo motor contains both a motor and a gear train in a nice package, but must be modified to provide continuous rotation. This website provides clear, thorough instructions for turning a servo into a DC motor which you can use for this project. (Such servos can be purchased very reasonably here.) However, while those instructions are very clear, this modification is still a lot of work. A simpler solution is to buy the units shown in Picture 2 from Pololu; they are less than $6 each. The link is in the Parts List.
To ready them for use on our breadboard, simply solder a wire to each lug on the motor (22 gauge solid copper works great). Cut pieces of Scotch foam tape (Picture 3) to fit, apply them to the motors and attach them to the breadboard. Line up the axles of the motor gearboxes and get them as perpendicular to the breadboard as possible. Place the motors as far to the rear of the breadboard as you can to leave room for the other parts. Then stick them to the back of the breadboard as shown in Picture 4. I used foam tape to do this, but you could use Velcro or hot melt glue to do the job.
Once the motors are in place, it's time to add the battery holders. We need two battery holders: one for four AA batteries and one for two AA batteries. We'll mount the one for the four batteries first right in front of the motors. Attach with foam tape, Velcro, or hot glue. Your breadboard should now look a lot like Picture 4 (except you won't have wheels yet). The two battery holder can be attached to the top of the breadboard wherever it's convenient – there'll be pictures later. Velcro works great here because you can move the batteries when you're building circuits.
At the front of the robot (or the back, you can make it go either way) we'll mount a roller ball. It is shown with the motors in Picture 2. Picture 5 shows one way to make the roller ball mount from a milk jug handle. After removing the handle, cut it to length with the hack saw and drill a 5/16ths inch hole in it. The roller ball will be a force fit into the hole. The finished mount is shown in Picture 2 also. Picture 6 shows the attachment to the breadboard. You could use a block of wood, or other scrap to mount the roller ball.