Tiger Strake Digital Fabrication

3D Design and 3D printing In this lesson we learned how to operate the Prusa 3D printers in the lab. We also learned how to 3D scan objects using the RevoPoint camera and software. Personally I found the results of the mobile app "Polycam" much better. This app allows you to use either the integrated LiDAR scanner of your phone (this is especially useful for bigger rooms) or photogrammetry. Photogrammetry uses multiple pictures of an object and digitally stitches them together to create a mesh body. This works best for smaller objects. The assignment for today was to 3D print something that could not be manufactured using another technique (or at least be very difficult to make using another technique). The second part of the assignment was to 3D scan something. For the printing assignment I decided to make something useful for my final project, the rocket. I designed a Thrust Vector Control (TVC) mount that relies on the material properties of PLA (Poly lactic acid, a 3D printing filament). It utilizes something called a compliant mechanism. The model can move, because the plastic is not completely rigid, but rather has some flexibility. Here is a picture of the digital 3D models: <img src="Screenshot 2023-07-16 at 21.59.03.png" width="500" height="500"> you can download the file <a href="TVC Tiger v3.step" download>here</a> This is how the 3D printed model looks like: Another honorable mention is that I used the 3D printer to upgrade my kinetic sculpture. This iteration now uses herringbone gears. The teeth of herringbone gears are angled inwards, giving them more surface area and helping them stay aligned. To create them, I used the Fusion 360 Spur Gear add-in and used the sweep tool to extrude the sketch around the z-axis. Then I rotated the teeth 25° and repeated the process for the upper half. 3D scanning assignment At first, I wanted to scan a NEMA 23 stepper motor. But this did not turn out as well as I hoped it to, so I tried multiple times. Since the results did not get much better, I settled on using a photogrammetry app called Polycam. I used Polycam to scan multiple Items: - A Nike Alphafly running shoe I scanned and 3D printed my running shoe. The scan turned out ok, but the bottom of the shoe had some pretty big holes. I ended up fixing this in Fusion 360 later, but next time I will have to make sure to take enough pictures and cover all angles. <img src="Screenshot 2023-07-18 at 19.05.58.png" width="500" height="500"> - Me I tried to scan me, which turned out to be more difficult than I thought. My first approach was to just try to stand still and move the camera around me. This did not work very well, as I could not reach my back and my arms were in frame. Polycam also did not stich the pictures together correctly as you can see here: <img src="Screenshot 2023-07-18 at 19.12.53.png" width="500" height="500"> - Me #2 I tried again to scan me, but this time I used another method. I mounted my phone and took a video of me rotating so that the camera would be able to capture every part of my head. Then I exported this video and opened it in Adobe Photoshop. From there I rendered the video and used the Photoshop picture sequence tool to export single frames. I uploaded these frames to Polycam and selected the best settings. Unfortunately this was the result: <video width="816" height="480" controls> <source src="4b93b1ee-db87-4a2e-98f5-83f03b1ba6f4.mp4" type="video/mp4"> </video> - Me #3 Finally! This time it worked. I asked a friend to take pictures of my head using the Polycam app. I changed some settings compared to my previous attempts and now it worked. I also cropped the scan a bit, because I used this for the CNC milling assignment. <img src="Screenshot 2023-07-18 at 19.26.08.png" width="500" height="500">