Prototyping a load cart: From design to a built output 👩🏻‍💻⇨ 👩🏻‍🔧

Growing up, I was a huge fan of Iron Man —The Mechanic of the Marvel Cinematic Universe. I still admit to the fact that I chose my college degree because I wanted to be like him. I wanted to build stuff and turn my ideas into reality. During the course of my college years, I did research on complex systems and spent most of my time in front of my computer, coding programs. Later on, I found myself working on a research laboratory that focus on prototyping scientific instruments and devices. This is still far from what Tony Stark does, but that's a science fiction story. Here's my story, my day's activities in working on a laboratory, the reality that I live in.

I like to draw the things that I'm thinking of, I see myself as a visual learner. I learned that when I took a computational physics course that uses numerical techniques for applications in solid state physics. Basically, we study and calculate parameters involving the lattice model. At first it was hard for me to imagine how would a lattice look like when it's sliced with respect to a certain plane. I understood it better when my friend explained it to me using a rubik's cube. So whenever I have to understand a numerical value, I try to ask what does this number look like? I draw a picture of it on my mind or on a piece of paper. For this one, I used the Autodesk Sketchbook as I work on my design in building a load cart and track.

No one gets it [easy] on the first try. That's the principle I live by in prototyping. There are times when thinking about the design of the product would take me days to weeks. The execution of planned designs is even more a difficult step in prototyping. A wrong measurement would result to re-doing a particular step. When you don't achieve the functionality of the thing you're building, that would mean you have to restart. An output that doesn't look good would call for a redesign. Prototyping means you'll have to work on the same thing over and over again until you get the best results.

In the past week, I've been trying to build a load cart that would hold a sensor and a set of masses. By designing my own load cart, I'll be able to accommodate the things that I'll attach to it like fitting two puzzle pieces. Also, I needed a small load cart, just the size of a palm so after sketching, I used Autodesk Fusion to create a 2D sketch of the parts. I usually use acrylic sheet as my material in prototyping since laser cutting is much faster than 3D printing. The downside of laser cutting is that acrylic sheets are costly, the machine consumes more power than a 3D printer, and you'd have to build your output from the 2D pieces you have cut. Wow, listing those reasons made me wonder why I used a laser cutter in the first place. Hahaha. I would probably re-do this using a 3D printer for a more simple and solid look.

After generating a .dxf file of my sketch in Autodesk Fusion, I used the software paired with the laser cutter machine to generate an .oux file. This tells the machine the shape of the piece that I want, the power of the laser, and the speed of the nozzle that will carve the design. Laser cutting could take from a few seconds to minutes depending on the area and kind of the material you'd want to cut.

Using screws, I attached the wheels of the load cart. To add friction on the wheels and the surface it comes contact with, I used an electrical tape to cover the acrylic. There was a mistake on the design of these wheels, it would slide off from the screw that's holding it intact with the cart's base. For the mean time, I cut a piece of paper as a stopper so it won't slide off.

Finding the right adhesive to use is a tricky task. There were times when my father would ask me why I know how to use epoxy when he thought I'm just facing my computer 24/7. I usually work with epoxy in gluing acrylic pieces together, it dries fast and clean compared to other adhesives.

The sketch that I started to work on last Monday is now the thing I'm holding in this photo. After a few days and with limited access to the equipment in the lab, I was able to build this first prototype. While assembling the pieces together, I found some things that I'd have to re-do. On the next prototype, I'm thinking of using a 3D printer so I can get away with the sharp corners. It was fun working on acrylic and screws though.