4. Individual Assignment - Computer controlled cutting¶
This week I learned about Computer controlled cutting using the laser and vinyl cutting machines
Vinyl Cutter¶
I started this week by learning about how to use the Vinyl Cutting machines available in the Fablab, these devices allow the user to cut materials into very fine designs and I can see it being useful for my final project in the way of allowing to produce attractive graphics or custom PCBs when using conductive materials.
To start off, I began with something simple using a calligraphic writing of my name I’d gotten from the web.
I used Inkscape to convert the image into a Vector, then turn the outline reduce
This was then transferred to a computer connected to the vinyl Cutter, I adjusted the setting and position of the sheet as the default would have moved the roll of vinyl too far down, although the width is determined by a sensor in the machine head.
I secured the vinyl roll using the clasp and made a cross-shaped test cut into the red vinyl, the default settings gave me good results.
I started the cutting operation and then cut out my piece from the larger roll.
Using a blade to carefully pick up the pieces I removed the negative part of the sheet leaving my design
I then placed down some transfer sheet onto my design and used a squeege to remove any airbubbles and ensure adhesion
Using the transfer paper and some pressure I applied the design to a surface of my choosing, I had originally intended to place the design on my phone and sized it for that, but if I were to do that I would not be able to document my process so I settled for placing it on my cover despite it being a holed surface
Laser Cutter¶
I used the Universal Laser Systems laser cutter for this part of the assignment. My task was to design a parametric construction kit that would use cardboard as their base material
Using Fusion360, I was able to define parameters such as ‘length’ and ‘thickness’ and my design would adjust as I changed them. This sort of modeling was something I was familiar with before as I had worked mostly in Fusion360 during my studies. By relating parameters to each other I was able to ensure the proportions of the pieces I was making remained consistent (e.g. the length of the slot will never be longer than the sides of the polygon)
The length of the polygon is determined by the user, but the thickness is a property of the piece of material you work with and so must be independent. Similarly the kerf is a property of laser and so is separate. It is important to ensure that all of these factors are kept within proportion, when using a thicker material it would be more appropriate to use larger lengths to ensure that dimension does not cause the design to act out.
To export the part, it is as easy as clicking on “Export as DXF” button on the sketch.
Onto the laser cutter, I had initially intended to use some of the 3mm cardboard as that material’s properties (cutter settings) and kerf were defined by another student in the FabLab, unfortunately we had already run out of that thickness. Looking around I found some sheets with thickness that varied between 6.3-6.4mm.
To use ensure proper locking in the construction kit I had to improvise, I made a finger-lock tester with joints that varied from 6.25mm to 6.42 and cut it out using the laser cutter. I had to guess what the appropriate settings were (I based them on for 3mm) but I got a decent cut on my first try.
settings
The pieces locked tight with the 6.25mm joint, it seems like the ‘springiness’ of the cardboard gave me leeway.
I adjusted my parameters and my designs changed to match, very convenient!
The pieces simply fell of the sheet with the above settings.
Flexure parts¶
I wanted to test out making a flexible joint for my construction kit, so I followed this tutorial to learn about cutting flexural joints.
To keep it simple and reliable I chose to use a linear cut joint.
Using the sketching tools in Fusion360, this is the sketch I produced.
Clearly, it’s not completely parametric, basic things such as length and thickness are but certain gaps and the extent to which the pattern extends might cause issue if the proportions were significantly changed
And the printing result was…
A small fire. Smolders starting forming during the cutting of the joints, on top of both ends being decapitated. Diagnosing the problem, I had:
1. Set the speed too low, which meant the laser’s heat was igniting cuts that were previously fine.
2. Forgot to delete some sketch lines.
I redid the settings, putting them as below.
Just by slightly raising the speed I was able to avoid the fire.
Success!
The construction kit now has flexible parts.
To construct something:
What are these? Perhaps three snakes fighting over a triangle?
A three leaf clover?
These parts add endless possibilities to the kit, though I do worry about their durability.