4. Computer controlled cutting

Group Assignment

In the group assignment we have to get to know the Lasercutter in the Fablab Kamp-Lintfort. We have to get started by testing and playing around with the different settings for the machine.

In the Epilog Laser Manual we can read about recommended settings for each material and thickness. In addition to a detailled documentary on lately done cuts and their settings is available in the FabLab.

To make sure the joints we cut are fitting perfectly, we have to do differently cut joints and try to find out about the KERF of the laser. The kerf describes the amount of material that is subtracted during the cutting process.

For a material with a thickness of 3mm, we want to try out the following:

The width of the joint we cut differs in steps of 0.05mm, therefore we can test how the different sizes fit together.

Another good tool to use when trying to find out the kerf of a laser, is to for example, take a piece of plywood with 100 mm length. Then we go ahead and cut for example 10 lines orthogonal to the length of the material.

Afterwards we measure the “new length” of the material. so if we have a 100mm, cut 10 times and afterwards have a length of 99mm, we have a kerf of (100 - 99)/10 = 0.1mm. (Just an example!)

The outcome looks like this:

Now I can try the different sizes of joints at put them together testwise. Therefore I found out, that for a material with a thickness of 3mm holds best together with a joint of 2.9 to 2.95mm.

Depending on how much I want the outcome to be able to be disassembled or not, I can vary these values.

Parametric Construction Kit

As an individual assignment, I design a parametric contruction kit.

To get started, I design two shapes. A square and a long rectangle. I set joints for both, so they can fit together. For that I use the knowledge I gained from the group assignment above.

I use Freecad to design the shapes I need for the construction kit. Afterwards I use the TechDraw workbench to add them to my Page. Therefore I select the body I want to put into the page with a double click and choose the perspective in the overview window (In my case: Top). Now I can comfortably export the sheet to dxf. This is the file format I need to use with our lasercutter.

Now I will print it using the lasercutter. Therfore, in our FabLab, we have a fixed computer connected to it using the software Rhino3D. I’ll open the DXF file with rhino and assemble and multiply the parts I want to print.

Similar to using a printer, I press CTRL + P to open the printing dialog. Here I need to set Power, Speed and Frequency for the material I want to cut. Speed: 7, Power: 100, Frequency: 20; I will use 3mm MDF for my kit and do not need raster cutting (engraving), only vector. Therefore I pick the following settings:

Just as a demonstration, the outcome looks like this: Obviously you would need a bunch more tiles to start making some nice contructions. My assignment just works as a proof of concept.

Vinylcutter

As another individual assignment, I design and cut my design using the vinylcutter.

I started off with designing a simple logo I wanna use for my final project. Again, I will design it using FreeCAD and export it as a DXF file for the vinylcutter.

I then import the DXF to the vinylcutter software, which is Silhouette Studio.

I multiplied my design to have some more stickers, chose yellow material and inserted it into the vinylcutter.

Now I set the properties for cutting, which is vinyl as material, cutting as an action and automatic cutting for the knife length. I check all my settings again and press start to let it print.

The result are some nicely cut stickers. Since mine resemble the name of my nephew, I’m gotta let him decide where to put those.