Introduction: Cardboard Chassis for Cheap Robots 2: Bugbot

About: I build robots out of boxes! I love teaching what I've learned and seeing people add their own ideas to what they've learned. Nothing excites me more than seeing a student really take an idea and run with it!

Following hot on the tail of my previous Instructable for Boxbot, I've got another cardboard robot chassis for you that I've named Bugbot!

Welcome back to everybody who read my previous Instructables, and howdy to those of you who are stumbling upon this for the first time! This is the third Instructable on mine in a series dedicated to kids and adults who want to get into robotics, but don't have the money or the patience to order kits online.

Robotics can be a pretty big investment, but for those of us just trying to dip our toes in, that can be really intimidating. How wise is it to invest upwards of fifty, seventy, frequently even over a hundred dollars into something if you're just starting out?

My goal is to provide resources for hobbyists who don't have access to machine shops or expensive gear, and to get more people involved in robotics in general. I make a point to use tools and materials that most folk can find around their house; things like scissors, hot glue, duct tape, and most of all cardboard.

Cardboard is a pretty fantastic material (so long as it's kept dry) because it is stiff, easily worked with, and rock-bottom cheap!


For more Instructables on building cheap robots, head to the For Cheap Robots collection, or for more things that I've done, check out my profile page!

For more info from Digilent on the Digilent Makerspace, check out the Digilent blog!

Step 1: Little Bot, Big Possibilities

As always, simplicity, functionality, and modibility are my goals with these cardboard robots, and this one's something of a favorite of mine. This little robot is easily the simplest of all my designs, but that simplicity comes at a bit of a cost.

Bugbot isn't as versatile as my other designs, because it's based off a chassis I created specifically to test out the effectiveness of direct drive motors, and you can actually see an early version of it in my Motors and Wheels Instructable. This means it won't work very well for gearbox motors or servo motors, but it performs fantastically for direct drive motors. Furthermore, I feel that this robot is also best suited to the DP32 from Digilent because of its built in breadboard.

That breadboard allows you to put all your sensors and circuits on your board, and because of how it's placed on this little guy, you can mount everything right up front. Light sensors, touch sensors, sonar proximity sensors, everything can be soldered right there, right away.

As far as first-time robots go, this guy's pretty great!

Step 2: What You'll Need

For this project you'll need:

  • Cardboard! (You won't need much.)
  • Hot glue gun. (By now you should probably have plugged it in to start heating.)
  • Duct tape.
  • Your microcontroller board. (I prefer the DP32 because it is cheap and powerful.)
  • Direct drive motors with duct tape wheels. (You can find out how to make these in this Instructable.)
  • Battery pack. (Four AA or AAA batteries are usually best.)
  • A bottle cap. (I think soda bottle caps work best for this, but any cap will do.)
  • Scissors! (Exciting!)

Step 3: Cut Up Your Cardboard

I usually use corrugated cardboard for my projects because of how useful and abundant it is. Corrugated cardboard has a grain to it, just like wood does. In this case, the grain is created by the corrugated layer in between the two surface layers.

In the pictures above, I've rubbed my cardboard with chalk so you can clearly see the imprint of the grain on the surface. When you cut your cardboard, you want to make sure your grain runs lengthwise along it. If you don't, your robot won't be nearly as sturdy and this design may not work for you.

Cut out a rectangular piece from your cardboard. I cut out a piece about 2.5 inches (6~7 cm) wide, and maybe 6 inches (~15 cm) long. That proved to be a good size for my robot, but I'd recommend you cut yours bigger. For Motors with a casing length of 1.25 inches (~3 cm) like mine, you'd probably do well with something more like 8 inches (~20 cm) long. You'll want yours to be at least twice as long as it is wide, and keep in mind that a bigger chassis may make it harder for your little wheels to hit the ground properly. Other than that, size really doesn't matter much, and I tend to wing it every time I make one of these frames.

Once you've got your large rectangular piece, cut it in half so you have two (approximately square) pieces. Then cut those most of the way up the middle, leaving a connection piece at the end. The length of this connection piece is going to determine how you mount your motors. I made this one a little too short (as you'll see later in step 7) so try and make it about as long as your motors, or a little shorter. This connection piece should be no less than half an inch (~1 cm) long, and you shouldn't make it any longer than half the length of your piece.

Step 4: Bend and Tape

Bend one leg of both pieces downward. If you bend the left leg of one piece, then bend the right leg of the other to make sure they mirror each other.

Now, tear off a piece of duct tape and place the unbent legs end to end against each other (the way they would have been before you cut them. Wrap the legs together so that the duct tape allows them to bend in the middle like a hinge.

The fourth picture in this set shows you generally what you should have by the end of it. The two back legs should bed down to touch, and the two front legs are connected by a hinge made of duct tape.

Step 5: Make an A-Frame

Hold the two bent legs of your cardboard frame together like the first picture above. Adjust them until you get an angle in the A-frame that you like. If you want, you can mark this spot with a pen or pencil by tracing where the end of one leg hits the other.

Apply some of your handy hot glue, put the legs back together, and gently pinch them together until the glue sets. Your A-frame should look like the fourth picture in this set when you're done.

Step 6: Cutting Corners

Carefully cut the corners off your ends. Don't cut too far, because you want to keep a good amount of this end area to mount your motors on. Keep the point right in the middle (like it is in the pictures) and relatively symmetric.

Step 7: Attach Your Motors

Start by wrapping your motors in a bit of duct tape. This will make it a little easier to remove if you need to replace the motors.

Next, test out a couple different positions for your motors. Depending on your preference, you can either tilt the motors backward a little, or point it straight up and down. What angle you pick should depend mostly on how tilted you expect your A-frame to be once the robot is fully assembled.

For example, in the second picture in this set, an angled motor mount works better when the frame is tilted back a little bit. In the third picture you can see that a more upright A-frame works better with a motor that's mounted upright.

For my robot, I decided an upright motor would work best, because I expected my A-frame to be upright as well. Here's where you can see why I said my ends were a little too short, because the end of my motor sticks up past where my cut ended. This honestly isn't a big deal, and you might opt to do this yourself if you want to make your robot a little more compact like mine. Just make sure you save enough room for you battery pack later!

Once you've decided on an angle, add a hearty dallop of hot glue, and press your motor on until the glue sets. Do this for both sides, and your robot should look approximately like the last picture in this set.

Step 8: Adding the Battery Pack

Flip over your battery pack and glue your bottle cap to the back end. This should only take three or four small dallops of glue. If you use too much, it'll make the bottle cap harder to remove later if you choose to salvage parts off this robot.

Figure out where you want to put your battery pack by holding it on your robot. Once you're satisfied, add some glue to it, and press it on.

Step 9: Attach Electronics

Hold your microcontroller against your robot, to figure out where you want to place it. If you're using the DP32, you'll want your breadboard to hang just above the ground. Give it maybe a quarter of an inch or half a centimeter of space. This way you'll be able to mount light sensors for line following, or bump sensors to keep it from running into walls or off the edge of desks.

Place a strip of duct tape on the back of your board. This will protect it from the hot glue and make it easier to remove. Now glue it to the front of your chassis, and you're practically done!

The last thing you'll need to do is wire your robot up, but because that can vary depending on what you want your robot to do, I've left that out of this Instructable.

Now your robot chassis is practically done! There is one more step, however...

Step 10: Make It Yours

Say "hello" to Flippy the Lazor Fish!

As I've said before, one the the big draws to using cardboard as a construction material, instead of a pre-designed kit, is that you can modify it however you want without worrying about permanently wrecking your hardware. In this and my previous Instructable, I used decoration as an example for how you can modify cardboard robots, but keep in mind that these modifications can be functional as well. I have plans for an Instructable on building a robotic arm using cheap microservos and cardboard, and then showing how you can mount something like this on your robot.

I hope this Instructable has been a help and an inspiration to all of you reading! Robots aren't always wire and steel. Your whole house is full of possible materials for robotics projects, and you don't have to be an engineer to get started on your own.

If you liked this Instructable or had a thought on how it could be improved, please leave a comment, and if you used it for any of your projects, please take a picture and let me see! Good luck!