Computer-Controlled Cutting

General concepts

- Laser: A laser (LASER, light amplification by stimulated emission of radiation) is a device that uses an effect of quantum mechanics, induced or stimulated emission, to generate a spatially and temporally coherent beam of light.
- Focus: In geometrical optics a focus is the point where the light rays originating from a point on the observed object converge.
- Vector: In mathematics and physics, a vector is a mathematical entity such as a line or a plane. A vector is represented by a line segment, oriented in three-dimensional Euclidean space.
- DXF: DXF (Drawing Exchange Format) is a file format for computer-aided design drawings, created primarily to enable interoperability between DWG files, used by AutoCAD, and other programs on the market.
- Power: In physics, power (symbol P) is the amount of work done per unit time.
- Speed: Velocity is the vector physical quantity that relates the change of position (or displacement) to time.
- Cutting: Laser cutting is a technique used to cut sheet metal parts characterized in that its energy source is a laser that concentrates light on the work surface.
- Engraving: Engraving is an artistic discipline in which the artist uses different printing techniques, which have in common the drawing of an image on a rigid surface, called matrix, leaving a print that later will house ink and will be transferred by pressure to another surface such as paper or canvas, which allows obtaining several reproductions of the prints.
- Marking: "Laser marking" means marking or labeling parts and materials with a laser beam. In this respect, different procedures are differentiated, such as engraving, removal, discoloration, annealing and foaming. Each of these processes has its own advantages and disadvantages depending on the material and the desired result.

(Source: Wikipedia.com)

Graphic concepts

Position of the laser focus

Laser tube process

Detail of laser cutting

Laser Cutter

Steps to use the machine
- The first step is to have a safe working space, as the laboratory has not been used for a long time we first arranged things and freed the machine from contact with hazardous materials, it was also important to mark the floor because of the distance of use. 👍







- Our machine is the Speedy 100 Trotec Laser and has the following features:

MACHINE SIZE
974 mm width x 765 mm height x 457 mm depth

WORK SPACE
610 x 305 mm

LASER TUBE POWER
12 to 60 W




- Font





- The next step was to calibrate the machine and put our files into the computer. For this we had seen that there was a flaw in the lid, months ago a fire occurred due to a bad maneuver or lack of supervision of the cutting in development, fortunately it is only a superficial damage. 😫








- As a next step we did a test on 4mm cardboard because happily we got an open store that only had that material.



- Everything seemed to be fine, however the parameters did not work when we had the larger pieces cut. 😩



- At first we thought that the reason why it was not working was because we got a message about the filter, I remember that the laboratory team told us that it had to be changed some time ago. In the following picture I show the lower part of the machine with the message "change filter". However, we talked to the LEFO specialist and he told us that it could be two things, either the focus is bad or the lens is super dirty and needs cleaning, so far we have concluded that it is the lens, we have done many tests and we have not achieved a good calibration.





- As can be seen in the following photograph, the tests did not change, when we increased the power a little and lowered the speed, fire came out and when we inverted the values, it did not cut very deep.





- Due to the inoperative machine and the short time available in the lab, we were not able to cut on the Trotec Speedy 100 yet, but we had the file of our designs ready as you can see below.



- The part can be designed in any program that has 2D/3D capabilities and that exports files in DXF (Drawing Interchange Format) format. We decided to create the laser tester in SolidWorks. While we were working on the design, we notice a problem… For some reason we notice that SolidWorks wasn’t creating the DXF file correctly. We saw a preview of the DXF file that SolidWorks was creating and some vectors were missing. This anomaly didn’t happen with older version of SolidWorks so we assumed it could be a bug exclusive to the 2020 version. The best way to solve this problem was to create a 3D representation so that SolidWorks could have a better idea of what we wanted. After doing this SolidWorks was able to create the DXF file perfectly.

Final design

- Well, it wasn't all bad, we got a laser cutter outside the Fab Lab and were able to test some of our files. It was important to see the difference in behavior of at least two different materials so we chose cardboard and clear acrylic. In order to be able to not only think in flat pieces we were also inspired by the Instructables pieces and generated some variants to test our cuts.



- The parameters we used were:

Cut:
4mm Cardboard: 60 Power, 1 Speed, 1000 PPI
4mm Acrilic: 30 Power, 0,3 Speed, 5000 PPI

Engrave:
4mm Cardboard: 30 Power, 100 Speed, 1000 PPI



This is the first experience we had as a team and we will come back to solve the Fab cutter system and also learn about the maintenance and cleaning of a laser cutter.💪

As additional information, after making the cuts we realized that the tolerance had a measurement of 0.15 mm, that is to say that if the original dimension of our drawing is 10 cm, when we cut it we obtain 9.85 cm, this is an important point to consider before making a very precise work. ✋

Special moment

Another thing I got from returning to the Fab Lab was to look at my previous work, when I was doing my educational workshops I was using part formats for the children to build their own creations. 😍 These were a lot of fun for them and simple enough to get them to work on their imagination, so I started using the laser cutter, giving them a purpose to use the parts designed in Rhino. 💪 What I liked most about these formats was that I could make them to any scale, the bigger the kids got the more fun they had. 😃

Vinil Cutter

Steps to use the machine
- First of all I had to see some tutorial on YouTube, I recommend this vídeo because is the official channel of this machine.
- When I became familiar with the information I started to open the box to see all the components, here are the pictures of what was sent to me.




- To understand the parts of the machine I built this next picture where I put the main parts, it is important to know this before using it.😄





-The next step was to start a test, inside the operation panel you have several alternatives, I chose the one to cut a text, for this example I used the name of my project.🥰



The next day I wanted to do more tests to get to know another type of letters and figures of the machine and I had a big problem. I had considered that I should not move the parameters because they had already worked the day before, however when I did the test with another color of vinyl it came out wrong, the letters had not been well cut and it was very difficult to remove them from the paper. It was frustrating because I could not find the reason, I made some changes in the parameters and it was still wrong.🥵



After several tests I did a review of all the variables to make the vinyl cut because maybe there was something I was forgetting, and so it was, I had noticed all but one; the cutting knife holder! When I checked it had one number less than the previous day, what happened was that the night before when I put it away it had been turned and it was marking the wrong number, this means that the reason why it was not cutting well was that the blade was too high. Fortunately when I went back to the previous number I was able to continue with my other tests, it felt great to find the solution!😃



After the wonderfuladventureit was time to continue on the machine route, our team is moving it from house to house to use it so my partner Stefany came to pick it up so we could work on her designs.Task accomplished!😍

FreeCAD

Exploring patrametric shapes
- To start exploring parametric shapes I made some figures in FreeCAD with the help of the Spreedsheet command that allows me to generate a table with the parameters I want to place. I made a circle of two different designs and each of them in different files that I will attach for review. I didn't find it too complicated but it does take a little time as you need to generate all the necessary constraints before changing any of the values in the table. 🤗

Fusion 360

Exploring patrametric shapes

- I really liked Fusion 360, it is the first time I explore parametric drawing in this program and I did not find it very complicated, it has a logic very similar to FreeCAD but has many more things that make this program more complete, besides the interface is much more friendly, the experience has been good but I needed to go step by step.💪

- First I got a tutorial to understand the logic of parametric shapes, I found this vídeo very helpful to know where the table of values was located and the mathematics that can be built to create relationships between the lines.

- Thanks to the first exercise I understood the sequence I had to follow to make the drawing I needed for my first parametric part. Although it has the same logic as FreeCAD, Fusion is a bit more complex to handle if you don't know the location of the configurations, happily I was able to quickly solve some complications in the process and this was my result.😃



- Finally, I have built with greater design complexity these three formats that are parametric to each other.

Rhinoceros - Grasshopper

Exploring patrametric shapes

- I am really impressed 🤩 for having achieved a good result in this program, I knew Rhino and Grasshopper but never put it into practice with such precision, it is definitely a software that requires a lot of patience and above all knowledge for the development of the designs but something that is helping me a lot since the first week is to first view the tutorials that can teach me to handle the commands and recognize the workspace.

- Thanks to the Barcelona team and the master classes prior to the Wednesday classes I was able to do a reminder of the program and thanks to the Fab LAT team we had some sessions to share information and teach each other. Working as a team in this kind of things is very important to be able to optimize the time and resources we have to successfully accomplish the weekly tasks.


-Well, this vídeo tutorial helped me a lot to create a prototype in a fully parametric way, it is interesting because at the beginning it may seem very stressful because there are many configurations but it really solves many things when you achieve it, it is possible to quickly get the perfect replica of a pattern and change any parameter, I really like how it works. very helpful to know where the table of values was located and the mathematics that can be built to create relationships between the lines.

Parametric construction kit

Laser cutting

- After all the adventure and challenges of not having a machine available I managed to make some cuts in two materials, cardboard and acrylic, the pieces were built in Rhino and Grasshopper, I really liked designing parametrically to cut, I had never done it before.

Download the files here

GrupalRhino
IndividualRhino
FreeCAD1
FreeCAD2
Fusion360