4. Computer controlled cutting

This week I wanted to prototype some final project ideas of the puzzle project using laser and vinyl cutting, along with using parametric modeling to make iterations easier to cycle through.

Parametric Grasshopper Model - downloadable files

The original puzzle above gets translated into a one piece parametric construction kit, below:

Here are the parameters including cube size, # of section cuts, the material thickness, and the kerf.

There are 3 main groups of code: Section Cuts, Notches at Intersections, and Cut Sheets

The first group, in the purple box, creates extruded section cuts in two directions (X & Y) through a starting shape, here a cube:

Here is the code fo the Section Cuts:

The second group of code places geometry at the intersections of the section cuts and subtracts it from the extruded section cut in opposing Z directions for each X & Y direction of section cuts: Geometric points (represented as green X’s) are placed at the intersections of the X and Y planes.

Boxes are placed at the X’s and are removed from the extruded planes to allow for notching. The primary challenge I encountered in the Rhino/Grasshopper parametric model was the offset direction in the red and green planes, when extruding them. There’s no way that I can tell to offset equally in 2 directions, thus providing a center line as opposed to an offset one. The problem this creates is that these parts are actually not symmetrical, but rather slightly off (based on the thickness of the material).

Above are the removed boxes in the opposing plane, in the opposed vertical direction.

Here is the code for placing boxes at the intersections and removing them (using SDiff - Solid Difference) from the planes.

The third group takes the notched section cuts, flattens them, orients them in the same plane, and arranges them for the laser cutter bed size:

Here is the code to arrange the cut sheets:

Rhino File Download Grasshopper File Download

Laser Cut Parts

Using the Rhino file above with the laid out parts, I created cut sheets to send to the laser cutter. Because I constructed a parametric model, I could easily test out different dimensions to find a good fitting notch: Above is seen a few different assemblies with different sized notches. The pair in the middle were about right.

Vinyl Cut Parts - downloable files

I then sketched on top of the parts my circuit idea, attempting make connections across the perpendicular parts, as a way of simulating a circuit.

Next I redrew the sketches in Illustrator and cut them out with a vinyl cutter.

They didn’t turn out quite as I planned, but good enough for now.

Here’s the vinyl cut right off the cutter. One challenge here was that the Vinyl cutter wouldn’t cut the AI file, so I ended up taking a screen shot of it, and then sending that screen shot to the vinyl cutter which then translated it into a readable file. What a bunch of wasted steps! in this process, the file was distorted and scaled, which caused the vinyl stickers to be a little too large. This process also added a double line around the actual part, so the geometry was even more distorted than planned. I think this is why I stopped using a vinyl cutter like 10 years ago…the software to run it is no good. just saying. I have heard MODs works better for the vinyl cutter, I will try that next time.

As you can see, the vinyl stickers are a little mashed-up to compensate for their oversize.

EPS Vinyl Cutter File Download

Group Assignment

We first sketched out what it could mean to characterize our laser cutter:

Next we drew our comb-like geometry in Inkscape as well as Fusion, then sent the files to the laser cutter:

Not all the settings worked so well:

We used a micrometer to measure the actual cut distance as distinguished from the drawn distance between the comb teeth:

We determined that the kerf dimension varies, ranging from .3mm to .4mm.

We also tested out what tolerance gives the best fit:

Without enough tolerance the cardboard deformed:

Instructor Feedback

Feedback given: “nice combination of laser and vinyl cut parts. could use more of a narrative arc - i.e. what are these pieces and why are you cutting them? What challenges did you run into? Also, the photos need more descriptive text - what is happening in each step? I can guess and infer, but you need to describe so that someone relatively unversed in this can at least follow along (and ideally replicate your steps). Also, you need more steps enumerated - for example: “Next I redrew the sketches in Illustrator and cut them out with a vinyl cutter. They didn’t turn out quite as I planned, but good” - show your drawing in illustrator, show your workflow taking it from Illustrator to the vinyl cutter. In what way did they differ from your plan? Why? What might you do differently next time? The group assignment looks good. Also - don’t forget to check your boxes!

Addressing the feedback

I added more text description to provide more narrative and also described some of the challenges along the way, also added some more pics/screenshots.