4. Computer controlled cutting¶

Assignment¶

• Individual assignment:

  • Cut something on the vinyl cutter
  • Design, lasercut, and document a parametric press-kit construction kit

• Group assignment:

  • Characterize your lasercutter’s main parameters (focus, power, speed etc)

Individual assignment¶

Vinyl Cutting¶

In the second week, I used the Inkscape software to vectorize an image of a tree that we will use in our final project’s design. With the goal of learning new tools and given that the lab has an Corel Draw license, I decided to do the image vectorization through this software. For the vectorization, first I searched for a Grogu image on Pinterest and downloaded it. Grogu is a character of The Mandalorian series, which belongs in the Star Wars Universe, following the thematic addressed until now.

After that, using the Corel Draw software, I created a new work, choose the A4 as the paper format (dimension workspace), and dragged the downloaded image from my download folder to the software. Then, I resized the image selecting only one of its vertices and dragging the mouse.

The idea is to create a sticker to put on my computer, so I decided to dimension the picture to almost 80mm. From that, just select the whole picture and then the tool “trace bitmap” -> “contour tracing” -> “high quality image”. After that, I set up the image quality parameters the way I like best and in the end, I have my vectorized image from Baby Yoda!

Below is possible to see the parameters that I use to vectorize the image

With everything done, now it is time to import the image to a vinyl cutting machine. The process is the same as a common printer. I made the purchase of a Silhouette Cameo 4 cutting machine but unfortunately due to the pandemic, the equipment has not yet arrived at the laboratory. I have access to Roland CAMM-1 Servo in the Insper Fablab, but due to pandemic it was not possible to used the lab now, but later I will prepare the image.

update: the Vinyl Cutting was done in the Insper lab with my tutor help. The main lessons to improve was:

• place the desigh (draw) properly inside the page area for begginer users make any cut straight forward (no need for adjustments); It is very hard to make any adjustment in a simple vinyl cutter (fablab style) and not doing it previously cause material losses (and time).
• Adjust image size to machine plotting area. The test that was made at Insper had image width set to 500 [mm].
• When the file is ready to cut, there are some setups to pay attention on: click ‘print’, click ‘preferences’, click ‘get from machine’ button for page setup, and also check material lenght (set it up for better material usage). Where it sais ‘rotate’ set it ‘off’.

The machine used in Insper for Vinyl Cutting was Roland CAMM-1Servo

Lasercut¶

Parametric design definition¶

After searching in some websites as Robazzo and Quora , I got the definition of Parametric as being values that have some effect in a process result. They can be simple like the amount of some material, or complex like an equation to verify the efforts in a structure. In the context of architecture and design, the parameters describe, code and quantify the options and restrictions existing inside a system. So, the PARAMETRIC DESIGN is the design that uses parameters and their interrelationships to define a geometric shape, where the object design is replaced by the process design, which generates the object.

Creation of the sketch/art to be parameterized¶

The theme chosen for my press-kit construction kit was Star Wars. I have been a big fan of the stories since I was a child, and I saw in this activity a chance to produce something fun that also reminds of the franchise. Thus, I based my project in a holocron, a device that has a regular dodecahedron shape. Right below, we have a picture that reminds the device of the fictional work.

Last week, I used the SolidWorks software for the final project’s design. Aiming at the spiral development, in this week’s activity I chose to use the Inventor software. I registered myself in the Autodesk website and sent a documentation proving that I am a university professor. After waiting for some hours, they sent me an e-mail informing that I get an one-year access to several tools like Eagle, Fusion, and etc., but for Inventor, I got a 30-day license. The first step was studying through video lessons on the YouTube Channel Thalmet where it teaches the basic of the software, see picture below.

To learn how to make the creation of the parametric model I watched the video from Lars Christensen.

The creation of a parametric model in Inventor is very straight forward. Open the software, in the home menu select the “Part” icon, then select the option “Make 2D sketch” and then select the plan you wish to create your part. From that, the process of selection and the utilization of the tools is very similar to what was presented on the activity Computer Aided Design performed in the SolidWorks software. Below, there is the sketch of the model of a parametric part created.

I made the initial test with 5mm thick, because it is the cardboard thickness and I got very good results of fitting as seen in the picture below.

After defining this parameter, I started the parametric design.

After the application of the extrusion tool, I selected the “administrate” tab and selected the “parameters” tool, and then we get:

The main advantage of using Parametric tools is that is possible to make relations with the variables and this can improve a lot the design process of the project.

From that 3D figure, I made some adjustments creating a new sketch above the part (trying to get closer to a Jedi Holocron) to add some details to the faces, and as a result I got:

Also, another part that was used as a fitting to fix a pentagon in another was created, thus forming the regular dodecahedron. Below, we got its sketch and parameters:

I used the 5mm tear width to ensure precision in the union between the fixing fittings and the pentagons, since this measure was approximately the same as the cardboard thickness. And the 10mm tear depth was chosen to ensure the fixing fittings would enter almost completely in the pentagonal parts. Below, we can see a picture of when I measured the cardboard thickness.

File preparation¶

Since the parametric project was created and the laser machine was prepared, it’s time to make the cuts. For that I used again the Illustrator software, capable of configuring projects for laser cutting and arts in general. The Illustrator can identify raster and vector designs, and has emphasis in vector designs.

File exportation¶

The process of exportation and configuration of the Inventor parametric project until the laser machine happened this way:

• Once the Inventor does not have compatibility with the Illustrator, I used the Autocad as a bridge between the two software, in view that the Autocad has compatibility with Illustrator. Thus, the Inventor file is exported to the Autocad format, as shown in the picture below:

PS: I used the DWG format in Autocad 2004 because for an unknown reason, my Illustrator version did not recognize the other Autocad versions.

• From the Autocad software, I made an adaptation on my parametric project, in order to optimize it. I used the “overkill” tool to eliminate repeated lines. This process is necessary once there are repeated lines and the laser machine will pass through these lines as many times as they repeat, which may cause an accident. To use the “overkill” tool, just type on the keyboard and it will appear

• Done that, I multiplied the image using crtl+C and crtl+V until I had 12 same faces to the project’s assembly. So, I saved it again in DXF format on Autocad 2004 to use it in the Illustrator.

• The same export process was made to the fitting and fixation part. Being multiplied in 40 part units to be cut two times, totalizing 80 fixing fittings needed, as shown in the picture below.

All the above mentioned process has the aim to vectorize our sketches, since we will use the cutting function by vector.

Cutting Parameters Configuration¶

When starting the Illustrator software, I create a new document using the same measures of the laser machine workspace, as shown below.

Done that, I select crlh+shift+P to search and insert my file in format DFX from Autocad 2004, and position it on the workspace created in the Illustrator. The pictures below show the entire process.

It is worth mentioning that it is recommended to apply 0.025mm in the traced units located on the top bar of the sketch options. This value is recommended for a better finishing of the parts with less material loss during the cutting. The same process was made for the fixed fitting part.

With all done step by step, just forward the projects like they went to a common printer, but on the printer selection tab, select the laser machine. Withdraw the autorotation option and it will automatically open the printer menu of the laser machine to configure the cutting parameters, as described below.

After this sequence of steps, select the printer icon and the document will be sent to the laser machine.

SPF Tests (Speed x Power x Frequency)¶

In the previous topic, we could see that I used 10% speed, 100% power and a frequency of 5000Hz. These values were used after a series of tests where I applied and analyzed the different configurations of values S, P and F suggested by the laser machine’s instruction manual to the cardboard.

During the tests, I noticed that the configurations suggested in the laser machine’s instruction manual were not effective to totally cross the cardboard. So, I searched for some FabAcademy work references from the past years and I could notice that many of them used the configurations of 12% speed, 100% power and 100% frequency. Then, I decided to test these configurations in a simple model from my project, and I got the expected results. Below, we have the simplified project and its result after the cut.

Group assignment¶

Laser machine¶

The laser cutter used in the lab is the Epilog Helix Mini 24.

Technical specifications¶

The Epilog Helix Mini 24 is digitally controlled and features an air cooled CO2 laser tube. The tube is a module and can be easily removed for maintenance and internal cleaning of the machine.

It is advisable to install an exhaust fan and an air compressor to better remove and redirect the gases that are produced during the laser cutting and engraving process. Below is a summary table of the specifications of the laser machine.

	Epilog Helix Mini 24
Engraving Area	24”x 18”(610 x 457 mm)
Maximum Material Thickness	8,5”(216 mm)
Laser Power	30, 40, 50 or 60 watts
Size (W x D x H)	36,5”x 32” x 39,8” (927 x 813 x 1011mm)

For more information about this machine access this link

How to use¶

In summary, the installation of the laser machine is similar to that of an ordinary paper printer, but the use has some peculiarities. All laser cutting and engraving machines have a fire risk warning, so it is advisable that during the operation of use the machine is never left alone. Therefore, in the laboratory in which I work, we have in our procedure for using the Epilog Helix Mini 24 a rule that there should always be two or more people in the laboratory during laser engraving and cutting operations. The following are the basic steps that must be performed, before exporting the file containing the cutting instructions.

• Connect the air compressor hose model GAST DC12 1/8HP, and approach the exhaust pipe model SAS 450 in the laser machine;

• Turn on the air compressor and the exhaust fan;

• Connect the laser machine to the SMS 3200VA current stabilizer;

• Turn on the laser machine;

• Present the material to be operated by the machine; (upcycling material), I recycled material that was not being used in the laboratory.

• Define the zero point as the machine standard located in the upper left corner, using the “auto focus” tool. A metal part is used as a zero point sensor as shown in the picture. The work table is then moved until it touches the metal part . The image below shows the metallic part.

After all these steps, I can start the job exported from Illustrator and the laser machine starts the cutting process.

KERF¶

The kerf is the space created by the laser cutting process, or the amount of material removed by the laser . The laser is dynamic and may change size and shape depending on the current, voltage, the flow of CO2 and the cutting speed. To analyze the kerf I used the cut made in the SPF(speed, power and frequency) test , where I created a simplified part of the project. In this way, I separated the cut pieces and gauged the measures of the internal and external cuts in the cardboard sheet . The image below shows the process.

Analyzing the data collected this way, I came to the conclusion that I should consider an average tolerance of approximately 0.20mm.

So with this new info I got back in the Inventor and adjust all my pieces considering the 0,2mm of the kerf, then I repeat all the process of exportation to Autocad and illustration and use the lasercut machine.

For pentagons:

For the fitting to fix a pentagon:

Cut¶

To demonstrate the laser cutting process, I recorded a simple video using the cell phone as can be seen below.

Note: Due to some configuration that I still need to improve the laser machine is cutting as if it were raster and not vector. :(

UPDATE I set the stroke to a hairline , in adobe illustrator I set the strole to .001. After that automatic the machine chance to a cut job or vector job. That is how the machine know that he has to cut it instead of engraving it.

And so I got the following result:

12 pentagonal pieces with centered holes and 60 fixing sockets

Assembly¶

The assembly process is very easy but need to pay attention not to blend the parts. First I determined one of the pentagons as the base of my dodecahedron, I added the sockets to the sides of the base, added the side pentagons until I formed a “basket”, and then I did the same process. Finally, it was enough to unite the two “baskets” with the fixing fittings to form my Star Wars dodecahedron holocron !!!

Notes¶

This was the first time that I used the lasercut as a cut machine LOL. In the past I played a bit with engraving images with SW themes.

Conclusions¶

Vectorize and parametric press-kit construction kit¶

• All the Inventor, AutoCad, Illustrator and Core Draw files done in this week assignment can be find in the repository

Autocad

Corel Draw

Illustrator

Autocad

MEMO: What I wanted to learn more¶

• In the next weeks I will try to use mods in the epiloglaser machine.

• Using spiral management I will also try using equations and relations in parametric tools to draw new parts.