In celebration of the International Day of Women and Girls in Science, I was asked by the local chapter of UNWomen to run a STEM-focused workshop for a group of girls aged 9 to 12-year-old and their parents as a way to inspire them as makers. I had a unit coming up about simple machines with our grade 4's so I thought it would be fun to test our some possible project ideas that I could try later on with them. I settled on cardboard 'automata' toys that incorporate cranks and cams. This would allow us to explore these mechanisms while leaving plenty of room for individual creativity. For the kids that wanted an additional challenge, I had motors, battery packs and buttons available as well.
Step 1: Materials
Dominos Pizza was nice enough to donate 50 boxes for the event and they were good to use. The cardboard is thin enough for kids to easily cut with scissors but strong enough to hold its shape. (I use pizza boxes a lot with my classes. Whenever I order pizza I always ask for a few extra boxes. When they hear I'm a teacher, most places are happy to pass me a few...)
We used the cardboard for the boxes, cams and pulleys etc., chopsticks or barbecue skewers for the cranks and cam followers and straws for the cam shafts. We used hot glue to put it all together.
Wire cutters made it easy for the kids to cut the chopsticks to the right length. It's easy enough for them to build everything first, then cut the sticks down to the right size when it has all been put together.
I bought a die cutter (Accucut Mark IV) this year that has turned out to be one of the most useful things in the makerspace for working with younger kids. While I think it's important for them to develop the skills to cut everything accurately and use a variety of tools, if they have to cut everything out by hand, it takes forever. Sometimes you want to keep the momentum going. I bought a die that does different sizes of circles. And more recently I found a local company that does custom dies for a very reasonable price. I got them to do the yellow one that you see in the picture with the different cams. Even very young kids can operate this machine on their own and cut out shapes.
Finally, I got some small DC motors, battery cases and buttons.
Step 2: Building the Box
For the prototype, I settled on a 5" cube. I cut two cardboard strips that were 15" x 5" and used the edge of a ruler to make creases at 5" and at 10" . These would fit together so that the top and bottom of the box are double-thickness. I showed the kids how to find the center of a square by drawing lines from corner to corner (many needed reminding) and punched some small holes with an awl. These holes would later be where the axle and cam followers go. I hot-glued the pieces together to make a box and used clothes pegs as mini clamps. Then I widened the holes a bit with a pencil so that the chopsticks could slide through freely.
Step 3: Cam Shafts
I made holes in the centers of the circles that I wanted to use to hold the cam shafts and the axle in place, and the ones that would go at the end of the cam followers. Then I hot glued the cam followers onto them. Once they were in place, I slid the cam shafts (straws) into place and hot glued the cardboard discs to hold them.
Step 4: The Cams
I punched holes in a couple more of the circles that were off-center to make eccentric cams. Then I pushed them onto a chopstick and checked the spacing between then against the two cam followers to make sure they were the right distance apart. Then I hot glued those as well and put the axle in place. (Notice the little twist drill in the picture. I have found these to be great to use with kids. I was very surprised how effective they can be and they only cost a couple of bucks.)
Step 5: Handle and Pulley
I made the handle with a larger circle and a cut-off piece of a chopstick and a pulley by sandwiching a smaller circle between a couple of larger ones. Then I just had to push each one onto an end of the axle, hot glue them to the axle (not the box!) and then snip off the excess bits of chopstick with the wire cutter.
Step 6: The Motor
At this point, it worked great. You could turn the handle and the cams bumped the followers up and down nicely. It was time to add the motors.
I glued a small bit of plastic on the end of the motor shaft so the rubber band wouldn't fall off, then I put a hole just above the pulley and glued the motor in place. Then it was just a matter of wiring in the batteries and the button , making a little hole for the button to poke through and then gluing them all in place.
Step 7: It Works!
The workshop was a big success. The girls and their parents had a blast. There was an amazing variety of project and every participant went home with a working toy. Only a few managed to get the motors in place but for a 2 hour workshop, I think we did really well.
I hope you find this helpful.