4. Computer controlled cutting¶
This week is all about using the machines. Starting off with the Laser and Vinyl cutters. I’ve been using these machines regularly for going on five years now so a lot of this, especially the design stuff, is already ingrained. Main things I need to get done are the group project, safety training, and the parametric construction kit.
Hero Shots¶
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It works!
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Sticky sticker sticks!
Group Project¶
You can see the group project documentation Here. My contribution was making different types of joints. I decided to recreate a design Neil showed during Wednesday’s lecture which was a set of different joints. The design file is fully parametric and includes the kerf as a parameter. While making this I did a quick kerf test and decided on 0.18mm as an acceptable margin where the parts wouldn’t stick permanently but still hold under friction.
Safety Training¶
I´ve been using and instructing people how to use the laser cutters here at the lab for several years. We have three machines, one Epilog Fusion 40 and two Epilog Mini 40. One of my regular job tasks is maintaining these machines. Cleaning lenses, Encoder strips and emptying the catch tray among other things. These are all 40W CO2 lasers. General rule of thumb is a maximum cutting depth of 6mm with the current lenses and power. Here at the lab we work mostly in MDF and Acrylic. Used to be plywood but due to supply issues we’ve had to switch to MDF for the time being.
As a fun exercise I decided to get Addi of cereal spoon fame to give me a quick refresher on the safety talk. I’ve condensed it down to some main points:
- Always check the machine is correctly set up. Focus adjusted and zero position correct.
- Make sure there’s nothing stuck in the bed that could tilt or lift your workpiece.
- Stay close to the machine while operating it.
- Triple check ventilation. The exhaust is turned on, Air Compressor active.
- Never operate the machine alone in the lab.
- Never operate the machine when tired.
The Parametric Kit¶
The main goal here is to make it as parametric as possible. I decided to make the whole design relative to two parameters. The material thickness and the kerf.
Design parameters¶
Changing the material thickness affects all the other parameters except the kerf. For example adjusting the “Pdist” is a matter of changing the multiplication of “MatT” in the Expression. The joints are patterned relative to the center of the design and each segment connected with arcs.
I designed this after doing the joints for the group assignment and used chamfers for ease of assembly. I considered using more “permanent” joints but I think this wouldn’t be nearly as fun to play around with if the joints weren’t easy to arrange.
| Parameter Name | Unit | Expression | Description |
|---|---|---|---|
| MatT | mm | 4 mm | Material Thickness |
| Kerf | mm | 0.18 mm | Kerf |
| Pdist | mm | MatT*5 | Radius between center of snap segments on each piece. |
| Dia | mm | Pdist*2 | Total Diameter between segments, From innermost part of joint to joint. |
| JDep | mm | MmatT*3 | Depth of Joints |
| CDep | mm | MatT/2 | Chamfer depth |
Cutting¶
After testing out the kerf during the group assignment I decided to go with .18mm of kerf which makes the joints just tight enough that you can shake them around without falling apart but not so tight as to be difficult to manipulate. The MDF I used wasn’t a uniform 4mm but close enough to keep the design file at 4mm. Setting the focus was tricky due to the material being slightly warped but I managed to orient it in a way where the cutting area was flush with the machine bed.
First test pieces came out perfect, Some required a bit of sanding to fit together. This was mostly due to variation in material thickness along the workpiece.
Assembly¶
I played around putting everything together in multiple ways. I ended up making some kind of quadrupedal square thing. There’s a lot more ways to attach these than I expected. I’d love to play around with more triangular assemblies later.
Behold!
Vinyl Design¶
I decided to re-cycle my design from the previous week and modify the knot pattern into a single knot. I just had to rearrange the pieces. Had some issues with the alignment due to copying it over to a non-grid document but re-enabling the grid and changing the snap settings fixed that. Finally to get the “line” effect, I had to select the whole piece, do “Object > Stroke to Path” and then “Path > Union”. This combined all the pieces into one single object. If I skip the first step I’d have cut along the edge of each piece meaning I’d have no gap between them to weed and without the second the cutter would have to retrace steps and skip around from one line segment to another.
Cutting¶
We have two vinyl cutters here at the lab. One older Roland GX-24 and one newer Roland GS-24. The process for both is almost identical. Main things being
- Make sure the sheet you’re cutting covers the length sensor
- Make sure the wheels holding the materials are within the white zones along the width of the material
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Make sure the machine is set to the correct cutting setting:
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“Edge” for cutting off the roll. This positions the blade along the bottom edge and measures the width for you. Remember to set the job length to approximately 1cm more than the document size. If you don’t change it the machine places it 1600mm above the bottom edge.
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“Piece” for a piece. This measures both the width and length of the material and outputs it to the print interface on the computer.
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“Roll” should be avoided if possible. It measures the width of the material but not the bottom edge. You have to manually position your starting position using the machine’s directional pad.
Weeding and application.¶
I weeded the center pieces out, leaving the outline and put it on my laptop. Getting it to stick was tricky even after cleaning the surface was tricky since the transfer tape had more surface area than the thin lines but I managed to make it work using my access card to flatten it as I peeled the transfer tape off.
Here’s the sticker after weeding and applying the tape.
and here’s the sticker applied to the laptop.
Design Files:¶
| Program Used | Description | Links |
|---|---|---|
| AutoDesk Fusion | The Parametric Kit | link |
| Inkscape | The Knot Sticker | link |
