4. Selected Fab Tool#

This module is divided into two different sections : Laser cutting and Repair Lab.

We learned how to design, prepare 2D CAD files and laser cut them. The goal of the first part was to create a 2D object with the material of our choice and to be able to assemble it together, so the two pieces must fit together.

For the second part, We learned how to repair a broken object by 3D printing. Both of the activities were very interesting and really fun 🤩.

⚠ Important information before using the laser-cut !#

  1. Know for sure which material is going to be cut !
  2. Always turn on compressed air (except for the Epilog, it’s automatic)
  3. Always turn on the fume extractor !
  4. Know where the emergency stop button is
  5. Know where to find a CO2 fire extinguisher.
  6. Wear proper goggles
  7. Do not stare at the impact of the laser beam
  8. Stay close to the machine until the end of the cut
  9. Do not open the machine while there is smoke inside
  10. Remove residue from the cut (if necessary, use a vacuum cleaner)

How to choose your material ?#

Here’s a list of different materials :

  1. Acrylic (PMMA/Plexiglas)
  2. Raw wood
  3. Plywood (plywood/plywood)
  4. Textiles
  5. Paper, cardboard
  1. MDF: thick smoke and very harmful in the long term
  2. ABS, Polystyrene (PS): melts easily, harmful smoke
  3. PE, PET: melts easily
  4. Polypropylene (PP): melts easily, produces a lot of dust
  5. Polycarbonate (PC), Nylon (PA), Polyurethane (PU): noxious smoke
  6. Fiber-based composites: difficult to cut, very harmful dust

Forbidden materials ! ❌#

  1. PVC: acidic and very harmful smoke
  2. Copper: fully reflects the laser
  3. Teflon (PTFE): acidic and very harmful smoke
  4. Phenolic resin, epoxy: very harmful smoke
  5. Vinyl, imitation leather: may contain chlorine (acidic and very harmful smoke)
  6. Animal leather: produces a lot of dust

4.1) Computer controlled cutting#

You have to install Inkscape to make your 2D design. If you are not so familiar with Inkscape, you can use this tutorial.

The two essential settings are speed and power. Be careful not to confuse these two ! To find out what is the optimal setting for your material, consult the test grids present at the fablab.

For example :

•  For a thick and dense material (such as wood), a high power with a low speed should be chosen.

•  For a thin material (such as paper or cardboard), a low power with a high speed should be chosen.

4.1.1) Full Spectrum Muse#

  • Maximum height: 6 cm
  • LASER power: 40 W
  • LASER type: CO2 (infrared) + red pointer
  • Software: Retina Engrave

Guillaume, the person in charge, asked us to do a test with a rectangle that itself has 10 small rectangles. We had the opportunity to use the Full Spectrum Muse, which has a maximum power of 40W. To use this laser machine, you have to connect your laptop to the same network as the laser cutter. We set the power to 100% and the speed to 20%.

We went over twice to be able to cut into the wood, but without success, we only managed to engrave it. Indeed, the laser is not so powerful to cut into this type of wood.

Our first test :

4.1.2) Epilog Fusion Pro 32#

  • Cutting area: 81 x 50 cm
  • Maximum height: 31 cm
  • LASER power: 60 W
  • LASER type: CO2 (infrared)
  • Software: Epilog Dashboard

Then I used the Epilog and tried to cut out the house, it’s an exercise in GitLab. When cutting, check that the thickness of the lines is less than 0.25 mm. To use this machine, you need to save your file on a USB stick. If the file format is not SVG, import it into Inkscape (File -> Import…). - Click on CTRL + P, then click on the name of the machine

  • Adjust the parameters like speed and power
  • Turn on the laser cutter with the key
  • Place your chosen material
  • Close the machine tightly
  • Start cutting

In order for the edges to bend, we had to put colors.

The cutting took only 30 seconds, it was very fast.

4.1.3) Lasersaur#

  • Cutting area: 120 x 60 cm
  • Maximum height: 12 cm
  • Maximum speed: 4000 mm/min
  • LASER power: 100 W
  • LASER type: CO2 (infrared)
  • Software: Driveboard App

Finally, we still had some time to use the lasersaur. And with this tool, we managed to cut our rectangle. The goal of this exercise was to find the kerf. I measured a kerf of 0.20 mm.

Don’t forget to turn on the water cooler (black button), the fume extractor (green button) and open the compressed air valve. If there is a problem, press the emergency stop button. It’s a big red button so you can’t miss it.

Kerf ?#

The laser burns away a portion of material when it cuts through. That’s why we have to take into account the kerf

The kerf is really important because the laser kerf burns some part of the material away, it can alter the detail of the design you are cutting. For example, if a design has a lot of small details, these can be lost because the laser is cutting more material than your design accounted for. The Epilog has a kerf of 0.3 mm.

Just for fun#

We finished with a little FABLAB logo, we used the Epilog to cut it. The logo was designed by Juliette. It took only 8 min.

My design on Inkscape#

It was not so complicated to make my design, I just had to assemble different shapes together. It’s a very simple and efficient design. Not only that, but it took only 1 min 23 to cut it by laser.

Final result#

Here is my little lama design, I named it : Tommy. Surprisingly, the two pieces fit together perfectly on the first try.

4.2) 3D printing for repair#

The course started by a little introduction of the repair lab, and then we were all given an electronic circuit, and we had to find the fault of the circuit, we were able to test the current flow of our cables using a multimeter. Personally, for me, it was the switch that didn’t work.

We also learned more about resistor, capacitor, diode, etc. We had the opportunity to learn about the basics of repair for electrical appliances.

Furthermore, we all had to bring a broken object. At first, I had no idea on what to bring but hopefully my sister gave me a little table from her toys that was broken.

To fully understand the 3D printing repair, you have to read this guide. I worked with Chris, and we designed our model on Blender. It’s a free and open source software for 3D animation, modeling and rendering. It features advanced modeling, 3D sculpting, UV unfolding and texturing.

4.2.1) Design on blender#

Our piece is made up of three parts :

1) The base#

2) The trunk#

3) The top head#

Just don’t forget to convert your document into an STL document, and you can print it with prusaslicer. Here’s my final design file

It took 1h23 to print it. We really simplified our model from the original design because the goal here is to see if the table can be reused.

4.2.2 Final result#

And it fits !! We are very proud of our creation 🥳 !! My little sister can finally start reusing the table that was useless until now.