Week 3: Laser Cut Press Fit Kit
My press fit kit design is designed to allow the building of model trees. To try and make the end result look as realistic as possible whilst using a few simple building blocks I wanted to exploit the fractal nature of trees. The length and diameter of each branch scales progressively at each node. I elected to have 3 branches per node and angle the branches at 45 degrees.
I decided to learn to use Inkscape for this task. It is relatively straight forward to use and the tutorials are good. The basic constructs for the design of the tree were roughed out on one layer and the shapes were drawn over these using bezier curves on a separate layer. I reviewed the advice available on ponoko.com for designing tab fixings and decided that, as the design requires relatively short slots, to use one long curve node in each slot with a height of 0.2mm. I produced a couple of test pieces with slot widths varying by 0.1mm either side of the nominal required width of 3.0mm.
In order to produce it on the laser cutter, the Inkscape design was modified so that all lines were 0.01mm width and then the resulting file was saved in pdf format. This was printed to the Epilog laser cutter using the proprietary driver.
Once I had confirmed the optimum slot width to be 2.9mm for the stock we were using I added the slots in all the relevant positions. I also modified the tree base as it was clear that it needed to be stronger. It is worth noting that if you clone the slots around the design, once you have used the Boolean subtraction to produce the finished shape, the cloning functionality desired to adjust all slots using one parameters is lost. Joel has a different technique involving masking which seemed to work more successfully.
I then cut the required pieces and the assembled the kit. Future iterations of this design need to be modified to strengthen both the slot fixing areas and the lower branches to allow them to bear the weight of the structures more successfully. I would also shorten the branch lengths to improve the design aesthetically.
Valentines Card
As I need to give a Valentines card for later this week, I decided to produce one to my own design in the Fab Lab. The design is based upon an Escher tessellation. The drawing was made in Inkscape. Cutting card on the laser cutter required optimisation of the speed and power settings to minimise discolouration from the smoke. The resulting cut out card still had some minor scorch marks and may be better produced on the vinyl cutter.
Charlotte's Egg Cup
My 12 year old daughter accompanied me on the lab day. She successfully learned to use Inkscape from scratch and produce and laser cut an egg cup to her own design.
