Week 3

Week assignments

Computer-controlled cutting

1. Group assignment:
   • Do your lab’s safety training. ✔
   • Characterize your lasercutter’s focus, power, speed, rate,
   • kerf, joint clearance and types. ✔
2. Individual assignment:
   • cut something on the vinylcutter. ✔
   • design, lasercut, and document a parametric construction kit, accounting for the lasercutter kerf, which can be assembled in multiple ways, and for extra credit include elements that aren’t flat. ✔

Group assignment

Link to week 3 group assignment

As the coordinator of the Fab Lab at the ETSAC in Coruña, I’ve been preparing documentation and using the laser cutting machine regularly since 2014. Access to our Fab’s info on SharePoint is open to everyone once they register. It’s a limitation of both the SharePoint tool and our University. I didn’t realize this when we switched our website from WordPress to SharePoint. In the near future, we need to move all our FabLab info to an open platform that anyone can access without having to register first. When we detect an error or malfunction in the use of the machine, we immediately publish a notice in sharepoint to all users, in the image is a sketch that I drew and sent to the users to correct an error in the arrangement of the height of the lens. My colleagues Pablo and Francisco had never used it before. On Thursday morning, February 9th, I gave them a detailed explanation about the safe use of the workspace, especially regarding the need to turn on the laser cannon’s cooling system, the machine’s smoke extraction, and the air compressor that prevents combustion waste from damaging or dirtying the lens. I also explained the importance of cleaning up and tidying everything up after using the machine.

Our machine is the PC 10/80KII, with has an effective working area of 1000x750 mm. Last December, we gave it a full check-up, replaced the laser cannon and the mirrors. The new cannon has a power of 150 Watts. We need to update all the cutting values for different materials on the Dixital ETSAC Sharepoint we use to share machine usage information with all the students and professors at the University of A Coruña. With the old cannon, which has now been removed, we had to keep lowering the head movement speed and increasing the power until it finally needed to be replaced.

My job as a member of the group this week was to inform and assist them in everything they needed for the safe use of the laser cutting machine, and as far as the use of our Silhouette Cameo 5 plus is concerned, to document its installation, features and first use.
Luis our FabAcademy instructor, was with us all Thursday and besides bringing us the material we will be using in the coming weeks, he taught us how to use the Silohuette Studio software and the Cameo cutting machine.

Individual assignment

Vinylcutter

In our fab, we have a Cameo 5 Plus, and we use the Silhouette Studio 5 program to send the cut paths. For a cutting practice, I used my website’s logo to make some stickers on adhesive paper, so I created a 3x5 matrix with the logo.

Silhouette Studio

The steps to set up the cut are as follows: after installing the Silhouette software, I connected the Cameo 5 Plus via Bluetooth.
I imported an image and then used the “Replicate” tool to create the matrix.
In the “Print and Cut” section, I checked the “Enable Registration Marks” box and printed the design on the adhesive paper.
Once printed, I placed the sheet on the Electrostatic MAT and loaded it into the Cameo, making sure to align it with the calibration mark.
In the Silhouette software, I selected the “Trace” option and prepared two different stickers: one with a cut that follows the blue color, and another with an offset.
Offset path I also defined the outer box and changed its color.
The blade on our Cameo is the Autoblade, and I set a force of 2 for the inner cut of the sticker and a force of 4 for the outer frame cut, so that the inner cut doesn’t go all the way through to the MAT, but the outer cut does.\

With a spatula and hook, I separated the cuts, and for the sticker with the blue outline, I used clear adhesive vinyl to transfer it onto my laptop. Although I prefer the one with the white offset.

In the review of Wednesday 12 February, Koharu Takeda shared with us in the group assignment the problem he had with the laser cutter in FabLab West harima. The fire situation freaked me out a bit, so I thought it’d be smart to make some warning signs for our laser cutter users. Basically, the idea was to remind everyone to stay close and keep an eye on the machine while it’s running.

I hopped online, found some cool foot-shaped images, vectorized them using Silhouette Studio, and then cut them with our Cameo 5 Plus. Check out the picture — the cutouts are basically saying, “Step here.” Pretty neat, right?

This February, our Fab welcomed two new recruits—Daniel and Ana! They’ve joined us with a collaboration grant from the University of A Coruña and will be learning the ropes with us until the end of May. This week, I showed them how to use the vinyl cutter, and together we made a sign to remind everyone that the laser cutter should NEVER be left unattended. It turned out amazing!!

Laser Cut

When I’m using the laser cutter, I always have to keep in mind that the laser beam has a fixed width and shape, even if it’s super thin. But the kerf width can vary depending on different factors. So, I can’t assume it’ll always be the same. I have to figure it out through trial and error for each material I’m working with. I also make sure to write down the kerf width along with the power and speed settings I used to get those results.

Grasshopper

To figure out the kerf of the laser cutter, I set up a parametric design in Grasshopper that lets me tweak the values on the fly. This way, I can adjust press-fit designs based on the results from tests with different materials.

I’m starting with a 4 mm thick MDF board. First, I cut a couple of 10x10 mm squares and some letters to dial in the cutting speed and power for this material. The goal is to get the cut done as quickly as possible without scorching the edges too much. After some trial and error, here are the settings that worked best for me:

For this material, I need to set a value of 3.55 mm to get press-fit pieces. As part of this week’s assignment, I have to design and build a parametric model that considers the kerf value obtained. I’ve been hooked on parametric design for years, so I’ve decided to create a strategy in Grasshopper to automatically generate different piece models to build the kit.

First, I tested generating a single piece by parametrizing the number of sides of the polygon, its size, and the geometric definition of the cutouts that allow it to connect with other pieces. Then, I completed the Grasshopper strategy by adding a grid where random pieces are generated with random segments and dimensions. In every case, I’ll place a label showing the thickness of the material based on the kerf value defined in the test. From Grasshopper, I baked a matrix of polygons with different sides and sizes, making sure all the joints fit perfectly so I can assemble the kit after cutting it with our laser cutter.

As we explained in the group assignment, the GCode for our machine is generated thanks to a plugin installed in CorelDRAW v.13. It’s an old version of the software, so I always like to run the file through VCarve Pro. Plus, this way I can use the Nesting tool to make the most of the material size.

Rhinoceros

In Rhinoceros, I could explode the text to turn it into curves, although I could also do this in VCarve since it’s easy to convert it to single-line text. In Rhino, I usually select the engraving option as you can see in the image, the resulting text is optimized for the laser cutter and specially for the CNC router.

Then, I exported the Rhino 3dm file to DWG [2010 Lines] and import it into VCarve Pro

Vcarve Pro

File > Import > Vector Import Ctrl+i Once the vectors are imported, I click on Nesting to arrange the pieces. I can set different tool options and clearances, such as tool diameter, clearance, and edge spacing. I can even enable piece rotation for a better fit and define the rotation angle.

In the images, you can see how much material is saved after nesting.

Then, go to Export > Selected Vectors to DXF, and this file can be imported into CorelDRAW without any issues.

Coreldraw

Once the SVG file is imported into Corel, I must assign the laser power and speed parameters according to the colour of each of the elements.
LMB > Laser parameters > click on each color to adjust the parameters > order the colors, first engraving, then inner cut and finally outer cut > LMB Path Generating path and sendint to laser cutter.
First, I choose one of the four possible origins. It must match the position of the material on the laser cutting table and the local origin that I must have set when placing the material on the laser cutter. Laser cutter. Setting the origin of the laser cut in the lower left corner Once the material is placed on the laser cutter bed, I can’t forget to calibrate the lens height using the acrylic gauge. Now that the gcode’s been sent to the machine, I can start selecting the path to kick off the laser cutting.

The steps to follow are these: first, I have to press the run and home keys in sequence—press run just a little before home. The first few times, it’s a good idea to keep the machine door open to avoid starting the previous job by mistake if the key sequence doesn’t work right.

Next, I choose the ‘inner file list’ option and select the gcode file I sent to the machine from CorelDraw. Then, I press OK once.

After that, I need to turn on the exhaust fan and the air compressor. Once that’s done, I can close the machine door and press OK again. The job starts now. I need to keep a close eye on it for any flames or excessive smoke. If that happens, I should stop the cut immediately by either opening the door or pressing the pause button on the laser cutter. Afterwards, all that remains is to assemble the pieces to obtain a figure that can be assembled in various ways and does not need glue to keep its pieces together. To demonstrate it, I can lift the assembly holding it with my hand without problem.

Non flat elements

To complete this task, I thought about creating a parametric model of a roof structure. The geometry control parameters let you modify its footprint, the number of frames along the X direction, and the angular distribution of the roof purlins in the X direction.

For the roof covering, I made a Grasshopper algorithm that stretches the cover over each section.

The material I used is a type of cardboard known as “cartón piedra”, with a thickness of 1 mm. In Spain, cartón piedra is a type of thick, hard cardboard used for crafts, models, and decoration. It’s sturdier than regular cardboard and kind of feels like solidified papier-mâché. It’s easy to cut, paint, and shape, so it’s great for creative projects.

I also ran a test to evaluate the kerf for this material.

Files week 3

LogoFab Silohuette Studio 5
Kerf Test 4mm SVG
Test PressFit Grasshopper
Bend cover Band SVG
Bend strategy Grasshopper
Ribs Roof structure 1 mm SVG