Group assignement: characterize your lasercutter’s focus, power, speed, rate, kerf, joint clearance and types can be found on our fablab website.
During this week, our goal is to materialize the logo that we created last week with the Inkscape program, using the adhesive vinyl technique. The logo consists of an original and attractive design that represents the identity of our project.
Once the logo file is finished in Inkscape, the next step is to prepare it for vinyl cutting. To do this, we can adjust the size, color and resolution of the logo according to our preferences and the specifications of the material and the cutting machine. For example, we can choose the size of the logo based on the space available on the surface where we want to paste it, the color of the logo based on the contrast we want to create with the background, and the resolution of the logo based on the quality and definition that we want. These adjustments can be easily made from the Inkscape menu, using the scale, fill and stroke, and export options.
After adjusting the size, color, and resolution of the logo in Inkscape, the next step is to save it as a format compatible with the vinyl cutting program. The most recommended format is DXF (Drawing Exchange Format), which is a vector format that preserves the quality and definition of the logo, and allows it to be easily imported into vinyl cutting software. To save the logo as DXF format, we just have to go to the Inkscape menu, select the save as option, and choose the DXF format from the available options. It is important that the logo is selected before saving, and that it does not have any effects or filters applied that could alter the result. Once the logo has been saved as a DXF format, we can import it into the vinyl cutting program and continue with the process.
Before adjusting the cutting parameters, it is important that we inspect the surface where we will stick the vinyl and measure it to ensure that the logo is perfect. The surface must be clean, dry and smooth, without dust, grease or irregularities that could affect the adhesion of the vinyl. We must also measure the surface with a ruler or meter, and mark with a pencil or tape the place where we want to place the logo, taking into account symmetry, centering and spacing. These measurements will help us adjust the size of the logo in the cutting program, and to place it correctly on the surface without it being crooked or misaligned.
In this photo taken from my colleague Charlotte'sCharlotte's website we see the vinyl cutter ready to start cutting, once the material has been placed in the cutter, we then load our design in DXF format into the cutter program, the Silhouette Studio and we simply click "send", the machine does the rest.
Now comes the most tense and fun step, which is transferring the logo from the vinyl to the chosen surface. To do this, we need to apply a layer of transfer paper over the cut out logo, which is a special paper that has a soft adhesive that allows you to stick and remove the vinyl without damaging it. We must press the transfer paper well on the logo, using a spatula or a card, so that it adheres to the vinyl and covers it completely. Next, we must peel off the transfer paper carefully, lifting the logo from the vinyl support and leaving only the cut out outline. Thus, we will have the logo ready to stick it on the surface we want, with the transfer paper as a protector. After rubbing a lot, a lot...
OUR MOMENT HAS COME:
On this occasion, and whenever possible, we are going to take advantage of this week's practices to advance our final project, which consists of designing and manufacturing a smart buoy that can detect pollution. To do this, we are going to use Inkscape and laser cutting to create a light signal that will be integrated into the buoy and that will illuminate with different frecuency. Thus, we will be able to meet the requirements of the practices, which are to create a design with Inkscape and cut it in acrylic, and at the same time give a practical and creative application to our work.
As all of last week's design was done PARAMETRICALLY in Inventor and you can see the step by step of the design, the parameterization and download all the files in this link, well this week I will try to try something different. I will do it in two ways.
I will focus only on the dome of the buoy, which is the part that will contain the light signal. To make the dome, I'm going to use laser cutting on a sheet of clear acrylic, and then I'm going to heat bend the acrylic to give it the curved shape. I will make the tube that connects it to the rest of the design in 3D printing, using a water- and sun-resistant material. As it will not yet be the final version of the buoy, I will oversize it a little to work more comfortably and to leave room for the electronic components that will go inside. Well, I have never folded acrylic, I will have to be careful not to burn or break it, and follow the instructions given to me in the workshop.
For the design of the box we have many options, we could import the inventor's 2D drawing, we could make a new one in Inkscape, etc. But no, we will use an online tool that will make our work easier. This is the makerCase website, which is a page that allows you to make parametric designs of boxes and other shapes for laser and CNC cutting, in a simple, fast and free way, we can make our design by entering the parameters that our design needs, such as measurements , material, type of joints, etc. The website will generate the plans in SVG or DXF format, ready for cutting.
As I said, once the figure is selected, you just have to play with the parameters, dimensions, number of curves, etc... complex designs are not possible, but a practical way to save time when designing boxes.
When we finish inserting the data into the makerCase.com website, we can download our file with the parametric design of the acrylic dome. The file will be in SVG or DXF format. We can open the file in Inkscape and make the changes we need, such as adjusting the size, color, resolution or outline of the design, but the most important thing is that the pieces fit perfectly as it will be guaranteed.
We already saw the easy way, now it's time for the real way, for them we go to Fusion and open a new sketch.
Once in the sketch, the first thing will be to make a rectangle, with the variables a and b, which will be our parametric dimensions on which everything will be supported.
then we will create the arcs, based on a(a/5), to soften the corners. For them we create one and then copy it or directly create 4, whatever is fine.
Now we create the teeth of the joints, for them we will use rectangles of one tenth of a and b, on each of their sides respectively. Like the previous one, you can copy or make 12 rectangles (this time there are more, better to copy and paste).
At this point we make a 6mm extrusion and we would have our first parametric piece ready.
Now it's time to make the body, the height is not a height we can decide, the problem is to define how long the piece would be. It would be easy to say that from 2*a+2*b, that the base is a rectangle, but that is not the case, since I made the 4 arcs, so the length to maintain the parametric design will be 4*(a-2* R), which would be the lines that remain from a after being subtracted by an R on each side, added to the arcs, which would be 4*pi*2*R.
We copied teeth but this time to make the female of the fitting so they will be inside the piece.
To make the lines where to bend the acrylic, nothing came to mind, so I drew a very fine rectangle of a-a/5 X a/200, leaving a rectangle of 80mmX0.5mm, and copied it many times.
ready, that's enough to start cutting.
In the ULB Fablab there are 2 laser cutting machines, one professional and another built there, and the latter will be the one we will use to make the cut. It is a Lasersaur type laser, this is a laser cutter with an outstanding price-performance ratio. We designed it to fill the need of makers, designers, architects and researchers who want a safe and highly-capable machine. Unlike others it's open source and comes fully loaded with knowledge to run, maintain, and modify.
The Lasersaur has a working area: 1220x610 mm (48x24"), which is nothing to sneeze at. With a power of 120W @ 10.6um (100W in long duration) that allows us to make deeper cuts in a smaller number of passes with a resolution: 0.1-0.03 mm (240-840 dpi).
To operate the lasersaur, a very simple web interface is used where you can vary the speed of the laser, the power, the position of the piece to be cut and the number of passes.
We adjust the parameters in the laser cutting machine program, which allows us to control the power and speed of the laser depending on the type of material and the thickness of the acrylic. For the cuts that will define the outline, we will use a power of 100, which is enough to cut through the acrylic without burning or melting it. To crack the sides, which are slots that will help us bend the acrylic with heat, we will use a power of 40, which is lower than the cutting power so that the laser only marks the acrylic without cutting it completely. In both cases, we will use a speed of 600 mm/min, which is a moderate speed that guarantees a precise and uniform cut. For the focal adjustment, which is the distance between the laser and the acrylic, we will use a piece that the workers of this fablab have provided us, which has a height of 13 mm, which is the optimal measurement for the laser to have the greatest power and definition. Thus, we only have to place the piece on the acrylic and adjust the height of the machine until the laser touches the tip of the piece. In this way, we can simply and quickly calibrate the focal adjustment, without having to use any other tool or measurement.
With the pieces cut, the next step is to bend the acrylic to shape the dome of our project. The logic is simple: we apply hot air over the slots we have made with the laser, and carefully bend the acrylic until we achieve the desired angle. But the execution is more complicated than it seems, since acrylic is a delicate material that can burn, break or deform if not handled correctly. I had to fold and unfold many times, trying to make sure the edges matched and the dome was symmetrical and wrinkle-free. Even so, the result is questionable, and it is clear that I am not an expert in this technique.
The result is far from being satisfactory, in many places the acrylic made bubbles and in others small cracks were created, anyway...I have to keep trying.In the following link are the design files.