Goal: Make 3 hardware sketches that move 1, 10 and 100 mm.
The 1mm sketch
I pondered about this task for a long time because moving something only ~1mm requires great precision which is hard to achieve with random junk around the house. Since the movement is small, the force must also be small and weak. Therefore, I chose to use static electricity to produce the 1mm movement. As the figure below shows, there are two aluminum foils hanging from a copper wire inside a glass jar. The goal is to separate these two aluminum foils using static electricity. I tried different items around the house such as a plastic ruler, a plastic fork, straws, clothing, a hairbrush, and a balloon. Some materials, such as the hairbrush and the balloon worked the best and produced the biggest separation. To collect the static electricity I rubbed these items on the carper and a wool blanket. As I touched the wires with the charged items, the two foils separated because they were both charged negatively. The best part was being able to neutralize the foils using just the touch of my hand!
This sketch is definitely in the minutes or hours level of sketching in relation to Moussette’s ‘levels of sketching’. One challenge was storing the static electricity and finding the correct material. Some materials stored static electricity faster while others failed to store enough charge to move the foils. In the future, I might spend more time studying the triboelectric series to find the materials that work best. This sketch could be used as an educational tool for teaching the concept of static electricity or perhaps making something move at a distance. I think it would be easy to control the degree of movement by changing the type of material or surface area of the aluminum foils.
Materials
Glass jar, insulated copper wire, aluminum foil, hairbrush or balloon
The 10mm sketch
The inspiration for the 10mm sketch came from my childhood when I did some physics experiments with my dad. Apparently, this sketch was published in an old physics text book and I have no idea about its scientific name. Initially, we used matchsticks, but they are almost nonexistent now, so I had to find another wooden material. This sketch works by stacking the sticks in a special way such that they provide a lever for the consecutive stick. When the first stick is pressed down, the energy is transferred to the last stick and the last stick moves upwards. The key behind this movement is in the tension stored in the wooden pieces. This sketch is in the minutes or hours level of sketching in relation to Moussette’s ‘levels of sketching’.
One potential challenge is the movement of sticks side to side, however, this can easily be solved by gluing them together. I also wonder if other materials could be used and how this change would affect the movement. I think this sketch could potentially be useful in a haptics system or as part of a robot arm.
Materials
Wooden sticks
The 100mm sketch
For the 100mm sketch, since the movement needs to be big, the stored energy and the force also need to big. I got inspiration from some DIY catapult videos on Youtube. This catapult design is quite simple and only uses a few robber bands to tie some popsicle sticks together. The popsicle sticks create a leaver system and the robber bands stored elastic potential energy as I stretched them. I tried various arrangements of popsicle sticks to store just enough energy to throw the eraser only 100mm. This sketch is in the minutes or hours level of sketching in relation to Moussette’s ‘levels of sketching’. The distance of the throw could easily be controlled by using other flexible materials, stacking more sticks, or using other rubber bands with different elasticities.
Materials
Popsicle sticks, robber band, eraser
