4. Computer Controlled Cutting (CCC)#

On this week, a FabLab tool formation was scheduled for us. We could choose between 2 options: Computer Controlled Cutting, learning to use a laser cutter; or Microcontrollers, learning the basics of sensors and motors. I was attracted to both formations and I chose Microcontrollers, because it is possible to have the laser cutter formation outside of the course. Everything was going so well, and suddenly..

Problems#

I fell very ill a few days before the formation, and thus I couldn’t attend it. Fortunately, there are these formations outside of the course, and they are free for ULB students! Wonderful! I went on the FabLab website to register to a formation, but… it seems like they are very popular. Everything was full for 2023. I was lucky that my professor Denis sent me an e-mail to suggest to add me to one of these formations. On the 10th of november, I attended the formation about CCC which I found very instructive and interesting. Denis suggested as well that I should set me a challenge using this machine, so I learn more deeply the usage of laser cutters and additionnally I have more interesting things to tell on this module.

How to use a laser cutter ?#

This machine is using a laser to engrave or cut planar materials. You can use it to engrave your name on a wooden plank, or cut a piece of cardboard very precisely for your architecture model, for example. The great advantage of a laser cutter is its precision and its speed. There are a few things to keep in mind when using it if you want the best results.

Security#

Basically, a laser cutter burns very locally your material, according to the pattern you want, and compressed air is blowed to avoid the combustion of the material. The process releases smoke from the combustion, that is why evey laser cutter has a smoke extractor paired with it. A laser cut always implies some risks, especially concerning fire. Therefore, there is a principle you should always apply when using a laser cutter:

“Always stay next to the machine when it’s cutting”

The nearest you are, the faster you react if something happens, the less damages you will have to repair. This rule is to be taken seriously as a fire can impact the live and health of everyone in the building. Here are some essential security instructions when you use the laser cutter: 1. Know your material. If you don’t even know what you’re cutting, you could release nocive gases into the room, fall asleep and never wake up. You may want to stay alive, so careful with the material properties. The material choice will be more detailed in the next section. 2. Check the solutions in case of emergency. Before using a machine, locate its emergency stop button (usually big and red), and the nearest CO2 exctinctor. 3. Protect your eyes. Even if the laser is covered by the machine glass, wear protection glasses when the laser is active. Also, don’t stare at the laser impact for too long. 4. Follow the protocol. There is always a protocol associated with your machine and it’s really vital to follow it strictly. Examples: Always turn on the air blow and the smoke extractors, never open a machine when there is smoke inside, and remember to empty the machine when you’re done using it.

Materials#

Let’s sort the materials and the specific precautions to take in the ones you CAN use, and the ones you CAN’T.

Materials you CAN use#

These materials can be used without any specific precautions, other than the security paragraph. * Wood * Plywood * Plexiglass * Textiles * Paper * Cardboard

Materials to NEVER use#

  • PVC, PTFE, Vinyl, phenol resin (toxic smoke)
  • Leather, synthetic or natural (persistant smell)
  • Copper (reflects the laser)

My challenge#

I fixed a challenge to myself in creating a 3D object using the laser cutter. I decided to build a dodecahedron (a solid with 12 faces) to decorate my desk. This solid is only made of pentagon faces. I drew the pattern and built a paper version to get some insights about the structure of such a solid.

The proper realisation of my project is not done yet since I reserved the laser cutter for in a few days. I already have a version of my model on Inkscape but maybe I can take these days of waiting to draw a second version, or another object.

Model file#

You need a model file you want to cut/engrave on your material. If you want to cut, you need a .svg file, that means a vector image (see module 2, Inkscape). The machine will apply a different treatment on every color you have in your drawing. It’s recommended to design with a colour code when you draw for a laser cutter. For example, the outline will be in red, the interior cuts in blue and the engravings in yellow. Let’s take for example the 3D object I want to build with a laser cutter: a dodecagon. I designed the pattern on Inkscape and I colored every treatment differently. Here I want the purple lines to be cutted through and the yellow lines to be carven enough to fold the cardboard but not to cut it.

That is the first version I want to print. I want to assemble it simply by folding along the yellow lines, and stick the purple lines together with glu to form the dodecahedron. So how would I put the settings to successfully get what I want ? The first thing would probably be a complete cut of the orange lines to carve pentagon holes in each of the faces. The second step would be following the yellow lines. The power-speed setting should be enough to carve in it in order to fold it, but not cut it completely. And the last step is the purple outline with a full cut (it has to be the last step because the whole shape could move and alter the drawing).

If you want to see my original .svg drawing, I included it in the files folder.

Using the machine#

When you go to the FabLab to laser cut your project, make sure to bring with you your .svg files on a USB key and you material. Personally, I used a 3mm thick cardboard piece. When you get there, unlock your machine by scanning the Fabman QR-code. Plug the USB key to the computer and open your file with Inkscape. Check if your drawing looks good and then print by pressing Ctrl + P. As a printer, select your laser cutter. The machine I used with Gala was the Epilog laser cutter, so here is a complete tutorial on using this machine. After I selected Epilog Engraver, the Epilog software opened and I could see my drawing on it. I had a few settings to make. I selected my drawing a I split it by color to apply a different treatment to each color. | Color | Speed (%) | Power (%) | | | |—|—|—|—|—| | purple | 10 | 90 | | | | orange | 10 | 90 | | | | yellow | 20 | 70 | | |

In this table, the colors are also in the order that the machines cut them. At the end I realised I could have done better: I could have put the purple step in the last position to make sure my whole structure doesn’t move, but there where no consequences so that’s ok.

After the cutting, I noticed the purple and orange steps weren’t powerful enough. The structure wasn’t totally cut, so I had to separate the two pieces with a cutter. The last step was folding my model to make the 3D shape and make it stick with some glue, and here is my final projet with the cutter!!