Fablab Aachen @ Fabacademy

Group Assignment

Week 03: Computer-Controlled Cutting



This week we got the following tasks:

  • Make lasercutter test part(s), varying slot dimensions using parametric functions, testing your laser kerf & cutting settings (in group).
  • Cut something on the vinylcutter (individually).
  • Design, make, and document a parametric press-fit construction kit, accounting for the lasercutter kerf, which can be assembled in multiple ways (individually).

Our Setup

The laser cutter that is available in our FabLab is a Epilog Zing 24 Laser, with a work area of maximum 610 mm by 305mm. In order to start working with it, we first turn on the laser cutter (the switch is clearly labeled), followed by also switching on the separate ventilation system. All of these can be seen in the images below. To interact with the laser cutter we use VisiCut which is installed on the desktop that is next to the machine. Below we will list the general steps that have to be executed in order to laser cut a model or a piece.

Our laser cutter seems to have taken off ...
Our laser cutter.
On off switch laser cutter.
The on/off switch for the Zing.
On off switch ventilation.
The ventilation controls.

General laser cutting process steps:

  • Select a material, some options we have available are: plexiglass (2mm to 6mm), finnpappe (1mm to 3mm), MDF (3mm to 5mm).
  • Set the focus on the laser cutter itself, this depends on the material chosen:
    • Put the chosen material on the laser bed.
    • Click the focus button on the laser cutter menu itself (for us it is located at the righthand side).
    • This will move the laser cutter "arm" a bit forward, so we can use the focus "pin" to set the correct value (images will follow).
    • Use the up/down arrow keys on the laser cutter menu to set the focus so the pin just scratches the surface.
  • Prepare the laser job in VisiCut.
    • Any model you make should be exported into the svg file format and put on a USB stick.
    • Plug the USB stick into the laser cutter desktop, and open the svg file of the model you want to cut in VisiCut.
    • Position it (and possibly scale it) on the canvas shown on the left hand side of the interface.
    • On the right hand side of the interface select your material from the dropdown menu, and also set the chosen thickness in the box below.
    • On the lower right hand side a tabbed menu is shown, in the first tab "mapping" you can select which laser cut function needed. The options are: cutting, marking, engraving and 3d engraving.
    • In another tab "position" you will be able to select a reference point on your model (center, upper left hand corner, etc.) and then position the model accordingly.
    • The final tab "laser setting" will be discussed in the next sections.
  • Sent the job to the machine.
  • Wait patiently for the job to finish, always keeping an eye on it for safety reasons.
  • Then wait another 5 minutes before opening it and taking the piece(s) out.
Our laser cutter seems to have taken off ...
The laser cutter menu.
On off switch laser cutter.
The focus "pin" that can be found of the laser cutter "arm".
On off switch ventilation.
The laser cutter desktop.
On off switch ventilation.
VisiCut left hand side interface: canvas.
On off switch ventilation.
VisiCut right hand side interface: settings menus.


Kerf Testing

Kerf means width of a cut in woodworking. Like other traditional saws, laser cutter also cuts through the material. Thus kerf is important property in laser cutting. Kerf varies accroding to the materials. With the same material, however, kerfs also get varied by difference in settings of parameters in laser cutter. It is advised to take kerfs into account by adding or subtracting them from the design(drawing). (Reference: What is laser kerf)

To measure a kerf, we designed a long rectangle consists of 20 small pieces(also rectangles). we cut them through using laser cutter and measured the gap using a ruler. And finally we got the value of the kerf by dividing the measured gap with number of vertical lines(20). Results from the experiment are as followed.

Materials Pinnpappe(3mm) Flexiglas(2mm) Flexiglas(2mm)
Power 100 100 60
Speed 80 40 40
Kerf 0.35(mm)/20
= 0.0175(mm)		 0.45(mm)/20
=0.0225(mm)		 0.35(mm)/20
=0.0175(mm)

Two different materials that we have used are Pinnpappe(3mm), Flexiglas(2mm). And we cut them using pre-defined setting in software that we are using. and we finally adjusted cutting parameters a litte.

What we learnt from the mistake. When we designed the experiment module, we made a width of small rectangles quite small, that small pieces got cut off and fell down to the bottom of the machine. Although we could assemble them back again, we could have escaped from it if we have made them bit more larger:P.

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Testing Different Cutting Parameters

To do by Jia

We use 2 different materials to test, one is glasses, another one is paper card. We use five group data set to test, the following are the details：

speed 100

power 100 80 60 40 20

speed 80

power 100 80 60 40 20

speed 60

power 100 80 60 40 20

speed 40

power 100 80 60 40 20

speed 20

power 100 80 60 40 20

We design stars in different colors. Thus, we can use color mapping to set different parametres.

Our results

Different materials have different optimal parameter, for paper card, speed 60, power 60 is the optimal parameter.

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