The goal of this excercise is to desgin and fabricate a Press-fit Construction Kit. The material to use is cardboard and it should be cut in the laser cutter. I decided to try different cuts and patterns on the cardboard in order to make it flexible. I also tested several geometries and joints to be able to assemble the components in a strong way so they wouldn't fall appart while streching them.
The final result is made of 6 hexagonal componets with cuts that allow them to strech. There are as well as 3 different joints that can attach as many components as you want to the final composition.
Download the file:Press-fit Flexible Cardboard [Laser cut Assignment] from Alejandra Diaz de Leon on Vimeo.
The first test was just about making cuts in the cardboard to see their behavior. I took a rectangular piece to engrave and cut some lines. I made the drawings in Rhinoceros. In this way, the cardboard streches when you pull it upwards. I made this in the Legend 36EXT Epilog Laser Cutter and use the following settings:
For cutting: Speed 95%, Power 15%.
For engraving: Speed 100%, Power 4%.
I kept this setting in the machine for all the tests.
The following step was to find a way to make a flexible module to press-fit with others. I tried this cross-shaped geometry which would have some flexible parts and would join to the other modules from its ends. For this one to work, only one part had to be pulled and the middle had to remain attached to something heavy to hold it down. So it was not ideal.
Finally, I tried different geometries that could be pulled from two sides. I tried diverse joints because they had to be very strong to resist the force of pulling the cardboard. The final output is the module shown in the pictures below. Although it's a planar geometry that can grow in all its sides, it becomes tridimensional when streched. At the end, the joints were strong enough and press-fit perfectly without any tolerance in the 2D drawings.
Something important to mention is that when you work with cardboard, you have to consider the direction in which you make the curs because it has an internal structure that defines the way the cardboard behaves. It was a fun excercise. Check out the video at the end of the page!.
