Accidental damage to our 3D printers during transportation delayed production of the student’s 3D models, but one of the other instructors was able to bring in her MakerBot Replicator 2 so we were able to complete the students’ designs with her help. Repairs to the damaged printers began this past weekend. While details of the damage were inventoried and repair supplies ordered, we explored the shelves for other projects left on hold from earlier in the year.
Notice of a new Raspberry Pi (a small single-board computer) came out this week. The B+ variation had four USB ports instead of only two and a SD Micro card storage interface in place of the older B model’s full size SD card connection. As we discussed the B+, several of the older B model were brought out and explored for uses supporting SOLID Learning or STEMulate Learning projects from an Internet Radio for in-car musical streaming to a video streaming source for mobile devices like smartphones and tablets (think “airplay” without the Apple brand products).
We had previously considered the OctoPrint 3D printer host control software, which has been ported to the RaspberryPi and together with an EDIMAX (under-$10 USD Wi-Fi transmitter), this seemed like the perfect system to monitor our printers remotely from the classroom. Copying the latest OctoPi distribution of Raspbian to an SD card and setting up various details (TightVNC for remote access, wireless networking, AVAHI zeroconf for easy access via browsers and many updates to the tiny Linux platform), we had the test set-up ready.
The web-based printer controls worked, allowing controlled diagnostics to be performed by two teams at the same time, but the MakerBot is not supported for printing due to its proprietary electronics and special file type for GCODE (s3g). On both Raspberry Pi test systems, everything worked as expected save the web cameras that allow streaming video observation of each printer. These are the B model boards (only have two USB ports each), so also required an external USB hub so that the webcam, WIFI module, keyboard/mouse, and USB connection to the printer can be managed at the same time.
After some trial and error, the inexpensive web cameras (picked up for $4 USD each at the last electronics swap meet) turned out to be YUYV format instead of the MJPEG format needed by OctoPi’s MJPG-Streamer application. By modifying the MOTION application’s code, the YUYV was able to be streamed properly.
./mjpg_streamer -i "./input_uvc.so -y" -o "./output_http.so"
Now with the added “-y” option, both Raspberry Pi boards are loaded and ready for remote control of 3D Printers once identified repair parts arrive and rework can begin.