Task #02
The task for the second week is to learn basics in a 3D modelling software and create a simple model of an object. Furthermore, we will make a custom sticker and cut it out using a plotter. And finally, we will create a laser-cut cardboard press-fit kit.
Model
For my modelling exercise, I chose the recommended Fusion 360 as my modelling software. I downloaded it, activated my free student license, and jumped straight into modelling. I picked a Rubik's cube stand as my reference. I measured all the important dimensions using a caliper. I sketched the triangular side first and then extruded it to 3D. I copied the 3D sides two more times and assembled them using the joint function. It was a bit tricky to figure out how to properly align the sides. I had to make components out of the extruded bodies first. After that, it was easy to connect the components using revolve joints alongside the outer edge. Finally, I united the three components and filleted the edges.
💡Tip: Fusion model in your web page
You can add your Fusion model to your pages by opening "Data Panel" in Fusion, clicking your account name and setting wheel option. It will opend "Administrator Console" in your web browser. There, you can go to your projects, show options and pick "Share". Select "Embed", pick size, copy the HTML code and paste it to your HTML file.Sticker
To make my own sticker I found a free SVG design of a lion online. I opened it in Inkscape and modified it a bit. I deleted really small componets and resize it. My idea was to create two-colour sticker. so, I prepared also the background and added small circles to help me align the two layers. I exported both layers in DXF to preserve the vector format.
For my design I chose blue and white sticker vinyl foil. To cut it out I first pressed the vinyl foil on sticky base mat and loaded it to the plotter machine. In the control system I opened my DXF file, scaled it, chose default options for cutting a vinyl foil and sent it to the machine.
After unloading the mat, I removed the unwanted sections using a small hook. Then I used a transfer foil which I put over the sticker of a lion. I trasfered it on top of the white circle. And that was the moment I realised I screwed up during rescaling in in the control software. You can see the slight misalignment in the picture. The outcome was a bit off-centered lion in the circle. Luckily, it does not look that bad.
Laser cutting
First things first, I had to think about what I will be cutting out using the laser. My idea was to create a bedroom with furniture. The furniture could be moved around, so, you could freely design the layout of the room. For the modelling part of the process I chose Fusion again. I sketched my vision and used parameters for width of the material and kerf (width of the laser beam). Then I extruded all the walls and base of the model to see the intended outcome when assembled.
💡Tip: Adding parameter in Fusion
MODIFY -> Change Parameters -> Add. Now, when modelling and entering "Sketch Dimensions", you just start typing the name of the created parameter and press Enter. The dimension can a quite complex function when you use other mathematical symbols like+-*/, constants or references to other
dimension (just by clicking on it, like in Excel).
I only sketched the furniture in 2D. I exported all sketches in DXF.
First thing before the actual laser cutting could begin was to define and set cutting parameters. There are three most important ones: speed, power and frequency. We defined them by making few square test cuts, setting the power to maximum and varying the speed. The speed and power go against each other. More power will deepen the cut, more speed would make it shallower. Generally, you want to cut through while maintaining the fastest movement. So you start with full speed, full power and lower speed if you do not cut through, and lower power if you cut through too easily. We set the frequency by the table value for cardboard, because that is what we are cutting. Also, we focused the laser on the cardboard surface with a help of small puck, which was placed under the laser head to define the right distance. Of course, we did not forget to turn on the air ventilation and filtration before cutting.
⚙️ Laser cutting parameters
- Laser cutter: FabCreator FabCore CO2
- Kerf: 0.25 mm
- Speed: 50 %
- Power: 100 %
- Material: Cardboard 2.4 mm
After inserting piece of cardboard in the machineand loading my DXF file into the control software, I checked my layout using "Frame" function which makes the laser head go around the bounding box of the area to be cut, so, you can check whether you do not exceed your pice of material. When everything was ready I turned the safety key and pressed "Start".
With a help of scalpel, because somewhere, specially corners, the laser did not cut through entirely, I took the pieces out and assembled the the room and furniture. The used ratio is 1:40 (25 mm in the model is 1 m in real life).
And the final result.
