This was final exam week at UAF. My partners and I had to finish our project and give our final presentation about it.
The device sits on a plywood box which holds the Raspberry Pi and the breadboard that contains the weighing circuit and RFID circuit. The keyboard, monitor, and mouse would be connected to the Raspberry Pi to access the user interface.
The base of the frame carries the circuit for weighing the filament spools. I put the force-sensitive resistors in place and ran the leads through holes in the plywood top of the box. If we had had time, it would have been nice to plan channels to conceal the wires. As it is, the FSR connectors are hot-glued onto the frame and the wires are bent into place.
The RFID reader fits nicely into a recess in the spool holder. Ideally, the reader would be located so it lies closer to the perimeter of the filament spools. Presently, the reader is close to the hole in the center of the spools, which means the RFID tags harder to read. Another improvement would be to have a channel for the wires. Presently, they are exposed as they run from the reader down through the plywood top of the box. Bending them to avoid friction with the FSR leads and the sides of the holes was quite a task. If the wires rub on anything it would affect the apparent weight of the filament spool.
Reconnecting the circuit elements above the box top with the breadboard inside the box took some time. I was careful to label the important leads, but there was some awkward balancing to do as I made the connections. It would have been nice to have hinges on one side of the box lid.
The day before the final presentation, I met with the partner who was in charge of the user interface. He and I were able to link my Python programs and another partner’s Google Sheet connection code into the user interface and get everything working together. The data that ends up in the inventory spreadsheet is correct and complete, but the format is not as conveniently readable as we would have liked. We just ran out of time to do better. However, the device works and the inventory system works.
Now, people who use the 3D printers could take a spool of filament, set it on the device, answer a few questions on the screen, and have the MakerSpace inventory spreadsheet updated. The staff could use the spreadsheet to make purchases when needed to maintain the proper stock of filament varieties.
I’m not taking any classes in the spring semester. So, I volunteered to come back to tidy things up and turn it over to them for use. My partners handled all the Node Red programming for the user interface and the Google API issues for the spreadsheet interface. I’m happy to finish up the project details because I want to learn more about those things. Such knowledge will be useful for my future projects.
