Assignment 4: a press fit toy construction kit.
The focus of this week is Computer Controlled Cutting techniques. We have used the lasercutter in the fablab to make a press-fit construction.
I made a toy-kit from waste acrylic sheets consisting of rectangular pieces, that you can connect together to make a little cube shaped puppet. People can play with the colours and the different faces. The pieces are cut out of left-over pieces that had engravings from other people in it, so each side is different.
The faces of the puppets can placed in horizontal and vertical configuration.
In the coming weeks I hope to make them into sensitive puppets by putting sensors and/or actuators inside.
The making process
Although cardboard was recommended for this assignment I decided on working with acrylic because I like the colours so much. l used 3mm acrylic sheet and set the speed at 1.5, power at 100 and ppi at X. I agree that acrylic is not the perfect material for making pressfit connections because it easily breaks.
The sides of the cube stay together because the pieces are squeezed tightly into each other. The overlap between the pieces that fit into each other was 0,2 mm for the material I used. Since the lasercutter also cuts away 0,1 mm each line, I needed to draw an overlap of 0,4 in my illustrator file. So the distance a in the image below is 0,2 mm. To avoid tension concentration the inside corners needed a little hole at the corners. See b in the image below. The outside corners c of the openings need to be filleted, to help align the piece that slides into it.
I also experimented with the vinyl cutter. I started with a sticker for my laptop, using the default speed and I set the force at 150.
Then I cut out a pop up card out of high quality paper. Here I had to lower the speed to 10 and set the force to 200 to make it cut through. You could do the same thing with a lasercutter, but the lasercutter gives burn marks that are not always desired. So from now on I will use the vinylcutter when working with paper or similar materials that have to remain clean.
In the meantime we have been struggeling a lot with Mercurial. I still find it difficult to imagine how it works and what it does - it is not very intuitive to me. Therefore I made a little drawing to remember what the commands actually do.