Engineering Documentation
October 5th, Thursday, 2023
Today, I have my self-designed card holder printed. The design process involves TinkerCAD modeling, Prusa Slicer parameter adjustment, and printing calibration
Interactive index
Gathering Ingredients Addition Subtraction PrusaSlicer Troubleshooting Reflection
The engineering design process is similar to mathematical operations. Something we are already familiar with can lead to a completely new invention with a different function by using subtraction, addition, multiplication, and so on. Therefore, a good start to the design process can involve gathering things we are already familiar with. During the brainstorming process, I chose a bed and a cat pattern.
Addition is a great operation. One ubiquitous example is the pencil with an eraser. A pencil and an eraser are two individual things at first. However, since they are often complementary to each other, someone ingenious combined these two into one for convenience. A bare bed can be as boring as Mark. Therefore, I'm adding this cat pattern to the bed. It's an easy addition, just for decoration purposes! Besides, I'm also adding a little semicircle with a hole inside on the open side of the bed to serve as a keyring.
Subtraction is also useful for creating new functions. Prof.Roy gave me inspiration through subtraction: if we remove the top of a shoe, the rubber bottom can be reshaped into a doorstop. I used to have this problem with my old card holder; I always had a hard time taking out the cards. This is why I decided to apply subtraction to the bed frame. I created a hollow semi-cylinder on one side of the bed so that I can grip the card, making it much easier to take out.
This was my very first time using Prusa Slicer. It took me some time to get used to its navigation tools. Prusa Slicer gives you a layer-by-layer view. This feature is especially useful for double-checking the structural stability of your design. You can also personalize your infill percentage as well as support options. The support is theoretically removable, and it's a good prevention for problems like poor bridging. The import and Hexport process can be overwhelming at first: import models into CAD software -> export from CAD software -> import into Prusa Slicer -> export from Prusa Slicer -> import into the USB Dongle. But once I got through it once, all the confusion went away.
My first design was initially placed horizontally, which meant that the card slots would be printed without support. This might cause poor bridging, which was my first error. To fix this, I then flipped it vertically and positioned the open side facing up, eliminating the need for long bridging. However, even after flipping the entire bed, the Prusa Slicer still warned me of poor support. Therefore, I checked 'everywhere support' and the 'brim' feature (essentially a skirt with a 0-mm separation from the model). After enabling these two features, the alert disappeared. Prof.Roy also guided me through some advanced features to ensure the print would meet my expectations. One of these features is raft layers, which ensures a smooth surface ready for the actual print. The second mistake I made was forgetting to switch to PLA material in the settings. Credit goes to Prof.Roy for pointing that out.
The final fruit is quite sweet! I'm satisfied with the overall quality. There's no poor bridging in the card slots, and the dimensions of the slots perfectly fit my cards. My self-designed semicircle notch also functions well: I can easily pull my cards out! However, there's one issue regarding the interior support. When I tried to clean the support, some of it stuck to the corners. In the end, I couldn't find a particularly effective tool with which I could clean the remaining support, so only 2 out of 4 slots function as perfectly as I expected. Prof.Rogers mentioned that there are specific settings which restrict inner support to some extent. This was a bitter but valuable lesson.