Cut the Cardboard Chassis

  • 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

Attach Motors

  • 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

Add Battery Pack

  • Mount the battery pack underneath the chassis between the two motors
  • A couple of piece of double stick foam tape will work well

Connect Wheels

  • 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

Affix Crickit

  • 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 In Power

Plug the battery connector into the Crickit power jack.

Connect Motor Wiring

  • 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

Add Speaker

  • 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

Connect Servo

  • 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.

This guide was first published on Jun 13, 2018. It was last updated on Jun 13, 2018.

This page (Build the Bumper Bot) was last updated on Jun 11, 2018.

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