- Draw some guides for cutting your chassis -- it doesn't have to match this one exactly, just so long as there's room for the parts you can get creative with it!
- Looking through the rest of this page will give you an idea of the size needed for proper parts placement -- make sure there's enough room between the motors for your battery pack
- Use a hobby knife or scissors to cut the chassis to shape
- A rounded front will work well for the bumper car action
- Use double stick foam tape to connect the motors to the underside of the chassis
- Keep them straight and even with each other so the cart will drive straighter than if they're offset
- Mount the battery pack underneath the chassis between the two motors
- A couple of piece of double stick foam tape will work well
- The wheels connect by pressing them onto the axles
- There are two flatted sides of the axle that fit the shape of the wheels' attachment holes
- The Crickit and Circuit Playground Express go on the top side of the chassis between the two wheels
- Play with the placement a bit so that the cart is slightly tail heavy to make sure it won't tip forward in use
- Use double stick foam tape to affix it
- You can double up or even pad the tape with a cardboard layer sandwich to make sure it sticks well, particularly if your Crickit has the rubber feet bumpers on it!
- Plug the motor wires into the Crickit's Motor 1 and Motor 2 ports
- Left motor goes to Motor 1 port
- Right motor goes to Motor 2 port
- Follow the pictures for black and red wire assignments -- getting this backwards isn't a big deal, because it can always be reversed in software!
Paper Clip Tail Dragger
A tail dragging bot needs something to smoothly glide across the ground while providing stability for the cart. Sometimes a ball caster is used for this, but we can get away with something much simpler here -- a paper clip! Our bumper bot is light enough that the humble paper clip will provide the needed stability and smoothness on the surface.
- Poke the paper clip through the tail as shown
- You can add stability by gluing or taping on a small piece of additional cardboard for thickness
- Use tape or poster putty to attach the speaker to the chassis
- Insert the wires into the Crickit's speaker terminals (either wire can go in either port) and then screw them down
- Use double stick foam tape to connect the micro servo to the chassis, leaving room for the servo arm to turn a full range
- Place a servo horn on the servo shaft so that it can sweep forward and backward
- Connect a popsicle stick or other material to the servo horn so that it can wave like an indicator flag
- Plug the servo connector into the Crickit's Servo 1 port with the yellow wire closest to the outer edge of the Crickit
Mount the Bumper
This step is optional, but you may find it helpful. You can add a cardboard bumper to the front of the bumper bot so that it won't accidentally drive over lower obstacles that are cleared by the chassis.
- Cut a length of cardboard that is a bit wider than the cart chassis and that reaches from the front down about 3/4 of the way to the ground
- Cut away a groove of the face and fluting along the length of the cardboard so it can butt up against the connection point
- Bend the cardboard to fit the curve of your cart's front
- Glue the joint and then connect the two pieces, holding them in place while the glue cures
Next, it's time to code the Bumper Bot with MakeCode.
