When I think of simple machines I think of things like these rudimentary automata with which we were examining the use of axles and cams. I realize that actual simple machines are much less complex and consist of things like inclined planes, levers, pulleys, wedges, etc. We at MAKETANK have an inclination toward kinetic art and so the exploration of axles and cams in these little boxes was right up our alley. This project offered the kids some tool use beyond the glue guns, and there was some vigorous use of hole punches as you can see below.
For the first day we used 6" x 6" cardboard bows cut in half so that we could get two frames from each box. Once they had their frame they marked a center line around the entire thing so that all additions would be properly lined up. Then marks were made equal distance up two opposing sides and holes punched to hold the axle. Rod and I pre-cut a bunch of 1 1/2-inch round wooden discs with a 1/4" hole in the center and an additional hole offset to take a small handle. These would serve as a crank once mounted onto the end of a piece of 1/4" dowel. In order to keep the box square the kids glued small cardboard triangles into each of the four corners. It was important not to permanently attach any of the cams as they were added to the axle as once they were fixed adjustments were limited as the axle could not be removed from the frame.
As you can see above, some were finding the cardboard triangles to be too difficult to deal with and employed wooden triangles for more rigidity. This was a great project. It lent itself to loads of personalization and creativity. It was another instance where kids had to learn to persevere through initial frustrations and set-backs to get to a place where they could find success and make the project their own. There are always some kids naturally better equipped for this than others. The joy comes in finding the right project for an individual child - one where they are so engaged with the concepts and possibilities that they are willing to stick with it through the annoyances and get to the innovation stage. This was that project for a couple of our kids, ones who usually gave up after one or two set backs but this time marshaled their personal resources and powered through.
In this project you can explore myriad combinations of cam shapes and sizes and placements to achieve desired outcomes. A round cam against a round cam off-set will make your upper component turn in a circle. An oblong cam on the axle non off-set can make the upper component go up and down. Staggering a series of these can make a caterpillar type motion. You can experiment with various shapes of cams (round, oblong, egg-shaped, nautilus, etc.) and their placement to achieve your desired outcome.
We found that if the vertical dowels were just poking up through a hole int he cardboard things were too wiggly. To solve this we set pieces of straw through those holes to provide some stability to the transaction.
Once people had their cams set as they wanted them and all of the spacing complete it was time to place some stoppers on axles on the inside and outside of the walls to keep things from slipping and sliding out of place so much. For kids who were really getting into this project the general wonkiness of the cardboard was getting frustrating (for me as well).
For kids who wanted to continue to pursue their design and use the cardboard version as a proof of concept we made some wooden frames the following week. These frame coupled with the wooden axles, cranks, and cams were much more pleasing to deal with. No matter what materials you use this is a confounding process as times but I look forwarding to finding the time to work on some iterations of my own again in the near future. Some really exciting end products are possible here and there is so much to learn and explore about how machines work and what is possible with small modifications. I know it isn't possible for everyone to make their own wooden components and the cardboard is a great option for initial explorations. But if you want to work on this for more than a day or two I really suggest finding a way to use wood, it is much more satisfying and if you have a good fit on components they do not need to be permanently fixed in place so they can be reused again and again with future students.