Introduction: Cardboard Chassis for Cheap Robots 3: Boardbot

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!

Hello again to all those who have been following me so far, and hello to everyone who hasn't read any of my previous Instructables too! This is my third and final Instructable in this series I've been doing all about cheap cardboard chassis for simple robots.

As many of you may have sussed already, I'm very passionate about making robotics cheap and approachable, and I realize that not every new robotics hobbyist is going to want to spend the money to buy the big expensive robotics kits. Kids who don't know exactly what they're getting into may be intimidated by trying to choose one, and risk blowing their meager budget on a kit that doesn't actually suit their needs. Teachers who have to supply kits to a full class room of kids don't want to have to shell out fifty dollars a kit if their kids might break them. Even Boy Scouts looking to complete their robotics merit badge won't necessarily have the funds for those expensive kits.

These Instructables are for them.

I focus on using cheap, everyday materials that you can find around your house. I use cardboard instead of sheet metal, scissors instead of band saws, and hot glue instead of an ark welder. I hope I can show you how you can use everyday items to build robots that don't just function, but function well and look good doing it!


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: Build a Boardbot

Previously I showed you how to make Boxbot and Bugbot using just corrugated cardboard and some other simple supplies. Boxbot was a versatile platform, with plenty of room for you to stick on modifications and extra hardware, but it's a little clunky. Bugbot was at the other end of the spectrum as a compact, efficient little robot specialized around a particular motor and microcontroller. Now I'd like to show you a chassis that acts as a nice middle ground.

Boardbot isn't nearly as large as Boxbot, nor is it as versatile, but neither is it as compact and specialized as Bugbot. It's design is simple enough to modify to your needs, and it's got a little bit of extra space that you can use to add on arms or sensors. Furthermore, it doesn't require you to have a box that isn't too big for your robot. Finally, unlike Bugbot, this chassis can be used with either direct drive or gearbox motors.

This Instructable will take you step-by-step through the process of building your own Boardbot. I'm going to focus on the design for direct drive motors, but at the end I'll give you a couple tips to modify those designs for use with gearbox motors too

So fire up those scissors, and get your glue gun revving! It's time to make a robot!

Step 2: Video!

By request, I've created two videos that take you step-by-step through the process of making the direct drive motor and gearbox motor versions of the Boardbot!

Step 3: What You'll Need

For this project, you'll need the following:

  • Duct tape. (As always.)
  • Cardboard. (As always.)
  • Hot glue. (As always.)
  • Scissors.
  • Robot brains. (I'm partial to the DP32 from Digilent, because it's cheap, powerful, and has a breadboard built in.)
  • Batteries. (Four AA or AAA batteries usually work best for boards like the Arduino or DP32.)
  • A couple of motors. (Either direct drive with duct tape wheels, or gearbox with bottle cap wheels, both of which you can find in my Instructable on Motors and Wheels for Cheap Robots.)
  • A bottle cap of some sort. (I like soda bottle caps, personally. They're plentiful and they work well.)
  • A ruler. (This one is pretty fancy. You can get it from Adafruit. If only this one was actually mine.)
  • A pen or pencil.

Step 4: Measure Your Robot Guts

Corrugated cardboard has a grain, just like wood does. This grain is created by the corrugated layer (in between the two surface layers). Also like wood, corrugated cardboard has a different stiffness depending on which way you bend it. If you bend cardboard against the grain (so it creases at a right angle to the corrugation) it will be much stiffer than if you bend it with the grain.

In this Instructable, I've rubbed my cardboard with some chalk so you can easily see the direction of the grain. You probably won't need to do this yourself, because it's easier to see what direction the grain goes when you've got your cardboard in hand.

Place your microcontoller and battery pack in the very middle of the board, in approximately the configuration you'll want them to be in on your robot. Then mark the widest edges, and the top with your pen. This tells you more about how wide and how long to make your robot.

It is also worth noting that the side of your cardboard you do this step on will end up being the underside of your robot. Here you can see that I picked a side with no markings on it, which was actually a mistake because it meant that the side with markings ended up being my upper side. Whups!

Step 5: Card Your Cutboard... Coart Your Cardbud... Cut Your Cardboard!

Lengthen the top line so it extends across your piece of cardboard, and then cut it out!

Step 6: Mark Your Folds

Our board needs to have the triangular reinforcements on each end to make it stiffer in both directions, but in order to make our folds straight and clean, we need to be very careful about how we cut and fold them.

In the previous step, after we cut our piece of cardboard off, we left two large flaps of cardboard on both sides of where we wanted to put our microcontroller and battery pack. These flaps will become our reinforcements.

Start by lengthening the width lines you made in step 3.

Now, measure the flaps and divide them into three sections. Mark these thirds on the top and bottom of the flap, and connect them with a straight line.

Do this for both flaps.

Step 7: Scour and Fold

Be very careful when using scissors to scour your flaps. Kids may want to have an adult do this for them.

You may want to make sure to have something disposable underneath your piece of cardboard when you scour so that you don't damage whatever surface you are working on.

Only scour the inner two lines that you made, and not the first line, because you only want to make two folds.

Also, make sure you don't simply cut all the way through your cardboard. You want to keep the second surface intact to act as a hinge.

When you have finished scouring your cardboard, fold it so that the crease runs along your scoured channels. If you fold your flap over so that the end approximately touches the first line, your folds should make an approximately equilateral triangle.

Do this for both flaps.

Step 8: Glue Your Reinforcements

Start by transferring your first line over to the other side of your cardboard. You can do this by simply making a small mark approximately at the end of your first line, but on the other side of the cardboard. Do this for both ends of the line and connect them with a straight line using your ruler.

Then, fold your flaps over so the end is at your new line, and glue!

Step 9: Add Your Robot Guts

Place your battery pack and microcontroller board on your cardboard chassis to see if they fit, and figure out exactly where you want to arrange them.

I chose to place my DP32 with its breadboard hanging off the end, so that I could add sensors later to make it into a line following robot.

Once you are satisfied with your board placement, flip your microcontroller and battery pack over and add strips of duct tape to their undersides. This duct tape will protect them from the hot glue, and make it easier to remove them if you need to replace them or work on your robot for some reason. You do not need to wrap them in duct tape, and personally I prefer to keep my duct tape hidden by tearing off strips that are slightly smaller than the components themselves.

Now simply glue your components back onto your robot. Make sure to place them where you had them previously, and hold them down firmly until the glue sets.

Step 10: Add Your Motors and Wheels

Start by adding your third "wheel". Flip your robot over, and place your bottle cap on the back end. Try to get it as centered as possible, and then glue it on with three or four small beads of hot glue.

Now take a moment to wrap your motors in duct tape. As with our battery pack and microcontroller, this duct tape will protect our motors from the hot glue, and make it easier to remove and replace our motors if we need to later on.

Check your motor placement before you glue it. It can take a little bit of effort, but if you hold your motor up against your robot's side so the robot is partially supported by the motor, that will help you place your motor so your robot is level.

Add a dollop of glue to your motor, and glue it in place. Make sure to hold your motor and robot steady so that the glue can set properly.

Do this for both motors, and your Boardbot is done!

Step 11: Gearbox Motor Variation

The major difference between this version and the previous is that your board only uses one of the triangular reinforcements on the back, instead of the sides. Keep the grain of the cardboard in mind when you make this style of boardbot. The cardboard grain always needs to run perpendicular to the reinforcement so the two will compliment each other's strengths.

You'll also need to make sure your chassis is wide enough to fit both your microcontroller and your gearbox motors. Then you simply glue them to the top of the cardboard, along with your battery pack and microcontorller.

Step 12: Make It Unique

This is the Speed-Mo-Tron Mark 1!

My favorite thing about making robots out of cardboard like this is you're not constrained by a kit. With a little ingenuity, you can make cardboard do just about anything, and you don't have to rely on a kit to have the specific part you need! This means you've got a huge amount of free space to try ideas and explore in. Best of all, if you mess up and break a part you're not in trouble because it was just cardboard anyway!

I hope this Instructable helped open your eyes to the possibilities buried in all those everyday items around your house. Those boxes you throw away could become your next big project if you think about it, and that old lid in the back of your kitchen drawer might just be the part you've been looking for.

I love to teach and I love to learn, so please if you have any suggestions for this Instructable, let me know! Also I'd like to see how people use my Instructables, so if you make something based off them, please send a picture my way!

Hope I helped inspire you! Good luck!