This week , we had to design and make pieces to test on the Instron machine (pictured above) in order to "measure the stiffness and strength of a structure and relate it to the material properties. I thought this could be a great opportunity to quantitatively compare the different test pieces that I was already trying to explore as structural materials for our future FabinaBox. Unfortunately, the Makerbot got some stage fright and didn't print as well as it was supposed to, so I ended up testing a pair of acrylic pieces to prove to myself the effect of grain on extruded acrylic. Turns out, they're not tha different after all!
3D Printing MTM Snaps
One of the proven types of structures for a Fabinabox-like machine is that of the MTM Snaps, a project by Nadya and her hairy colleague. The novelty of the test piece (green snaps above) are a great form for us to start from, so I decided to test this as dependent on the material it was made from. I wanted to test the original ones made of HDPE, but didn't get the sheet of material in time, so I attempted to 3D print my own in Morris's lab's MakerBot (Thanks, MVL!).
Lasercut Acrylic Test Pieces
With better resolution:
Using a combination of Neil's notes and Wikipedia's equation for Stiffness: k=(AE)/L,
And it works! Got it on the right part of the chart!