February, Tuesday 12th 2013
Assigment: Design, make, and document a press-fit construction kit
1. Laser Cut
This week assigment was to use the Computer-controlled cutting machines. We were introduced to the Laser cut machines and the Vinyl cut machines.
We have 3 laser cutters in FabLab Barcelona. 2 small ones and a big cutter. At first we were supposed to use the Epilog Legend 36EXT and alternatively the Spirit GE LaserPro.
The Epilog has a 900x600mm bed and the Spirit GE a 950x450mm bed.
We were to use 7mm Carboard. The only one able to cut this thickness was the Epilog.
We had problems with the Epilog so we tried with the Sipirit GE but we had no luck cutting 7mm carboard. Even though we tried different Speed and Power values the laser couldnt get througth.
So the next option was the big laser cutter. The advantages of this machine, at my point of view, are a lot. There are a bunch of parameters you can modify than the others cant.
So I began my research for a press-fit construction kit.
At first I thought about making a 3D design in Rhino and making the pieces with 123Make software. This option was OK, but I think I could make a more Inteligent design. So I decided to make a modular-periodic structure.
I decided to make a minnimum number of typologies as to achive a more complex and modular system.
The basic geometry is a Dodecahedron.
After looking for some references I found that this kind of system could be achieved with only 2 pieces. So I went for it.
Piece A has 3 connectors and Piece B 4 connectors. The ratio to make a complete dodecahedron is A = 2B.
A
B
I made a mistake at first and tried a connector of 6.95mm. When I laser cutted the pieces they were too big.
So I went for a 6.5mm connector. This value was just fine.
A + B basic connection
4Bs connecting to 1A
Semi-Dodecahedron 3D model
After studying the geometry I decided to prepare the pieces for laser cutting. I used a 900x600mm carboard / 7mm thickness.
I this case I made 8 A pieces and 16 B pieces to complete 1 array plus 2 extra B pieces since I had space in the carboard.
Prepared pieces to lasercut
Since we were cutting in the big laser cutter, Luciano explained us how to do it. This machine is not connected to the FabLabs WiFi but to a dedicated PC. We had to export our files to .DXF for the Enrouter software to read it.
I imported the file and make the adjustments needed. I used a In-Out cutting strategy since I had inner cuts in my pieces. I saved the file to the machine and configured it to cut.
Here some images of the process.
You have to adjust home position, laser cutting height and thats it. It is a very straight forward process. Since I only had cutting lines and no engraving I only used PEN1. I would like to engrave something in the future as well just to try this feature.
Here some images of the results.
Final lasercut pieces + pieces from first wrong test
Several images of the structure.
Basic press-fit connection unit
2. Vinyl Cutting
The second part of the assigment was to use the vinyl cutter. We have a Rolan in the Fablab.
Configuring this printer in my Mac was a little tricky.
I had to install FabModules, not that straight forward as it seems. When I managed to do it I decided to relate the vinyl cutting with the same design of the laser cutted dodecahedron structure.
I made a 2D capture of the 3D model in Rhino and cleaned the lines until I had only outlines.
Then at first I export it to illustrator and after that to Photoshop to fill the outlines with a solid black. Then saved the file to .PNG format.
A 120x120mm PNG.
I imported it to Fabmodules and send it to print.
Here some images of the process and the results.
Outline imported in Illustrator
PNG after Photoshop editting
Fabmodules import
Cutted vinyl