JetSet has now entered the third major phase of the design process: making. Until the end of the semester we will be ordering materials, modeling our device with 3D modeling software, and building our first prototype (no, not drawing, BUILDING). It’s pretty exciting!
I’m especially enthusiastic about this stage of the design process because I get to rekindle my long-lost relationship with Autodesk Inventor. No, I’m not saying that sarcastically. Using AutoCAD software was probably the first thing that drew me to engineering when I was in seventh grade PLTW and I got to design bird houses and pinewood derby cars on the software. I got to use it again in ninth grade Introduction to Engineering Design, and I’m thrilled to get to work with it once more.
I originally made a rough model of our device in Google SketchUp. However, in my opinion SketchUp is more suitable for larger models, like houses or vintage travel trailers. In SketchUp it’s harder to make separate components and join them together, like sliding a string of beads through and axle and still allowing them to rotate and slide back and forth. The reason I initially modeled our device in SketchUp was because the program was already installed on my computer from tenth grade DAP. After I’d created the model, however, I realized you could download a three-year student trial of AutoCAD for free!
In the midst of my excitement I accidentally downloaded the wrong package of AutoCAD programs, including Autodesk 360, Autodesk Vault, DWG TrueView, and AutoCAD (I wanted Autodesk Inventor). I didn’t realize this right away, and at first tried to model the device in AutoCAD 2015. I was having trouble extruding my sketches, and all of the commands weren’t in the places that I remembered- it was very frustrating. I went back to the Autodesk website and realized that Autodesk Inventor was the program I was looking for, and after downloading and starting it I was greeted with the familiar layout that I once built train cars and castles with.
I started out by modeling the base. I used the size of my laptop and a ruler to gauge how big I made the design (we want the device to fit comfortably in a backpack or carry-on bag, while still providing room to move one’s feet). Then I designed the axles and the beads that would slide along the axles. On the base model I sketched how far apart I could space each of the axles, and then used these measurements to determine the maximum width I could make the beads. When making the axles and beads I got to refamiliarize myself with the “revolve” tool. Revolving, like drawing three-point arcs or grounding components, was something that I had to figure out through trial and error. Autodesk has a bunch of helpful tutorials through their online Knowledge Network, but I found that I could solve most problems I ran into by tinkering around by myself faster than if I took time to watch a video.
After I created the four components I opened an assembly file and started joining them together. The biggest challenge I ran into during this modeling process was deciphering the error messages, which I got a lot of when trying to constrain and add joints to the components. For instance, I could slide a bead onto an axle, but then when I tried to flush the axle with the base, an error message would say “relationship with undefined geometry,” and a flurry of yellow exclamation marks would dot my screen. I solved this problem by flushing the axles with the base first, and then sliding the beads on. Because the base is grounded, the axles also won’t move, so their geometry will always be “defined.”
After a lot of challenging work I designed a model I was proud of, and knowing that I overcame many small, tedious obstacles along the way made my accomplishment even more rewarding and makes me eager to keep improving my model. My design is nowhere near perfect- one particular area that needs improvement is the pedals, which currently are not compressible or moveable in any way. Annalise may take on this challenge, since she’s also in engineering and may want to further her 3D modeling skills.
Our 3D model will help us in our search for the appropriate materials, as we will be able to see the approximate dimensions we want our components to be and how they’ll fit together. When we construct our prototype we’ll get to utilize our school’s newly revamped Maker Space, which has a plethora of tools and equipment to aid us. In fact, JetSet has already taken advantage of one machine in the Maker Space: the MakerBot Replicator, a 3D printer. We attempted to print the 3D model I designed, but some complications with file types and flash drives prevented it from happening this week. It’s possible that we’ll also use the 3D printer to print out our device’s base, since it’s specifically designed for our invention; curved surfaces like axles and beads are harder to print, and we aren’t sure whether we’ll be able to find a foot pedal as large as we need, so that may be printed in parts too. It’s going to be an interesting (and challenging) six weeks!