As part of Acer’s Seize The Idea contest I’ve been looking around the house at my half finished DIY projects and thinking of innovative ways to use one of the Acer products to finally wrap a few of them up. Since nearly of all my recent projects involve one or both of my 3D printers, it seems fitting that I should take this opportunity to solve a little control issue I’ve been having.
As it sits now I have to dedicate a laptop to the printers, and can only print with one at a time. I’ve been eyeing an open source project called Octoprint and how to set it up to control one or both printers. A single board computer like the Beagle Bone Black or Raspberry Pi will provide more than enough processing power plus USB and network connections. Octoprint can be accessed through any browser, and can even stream video of the printer in action. This is useful, but I still need a laptop or another computer to run the browser.
My plans now, are to use the Acer Switch 11 on the printer table as a semi-permanent display for controlling the printers. If I want to walk away and watch TV or sit in the other room with the wife or kids I can take the Acer with me and continue to monitor the print. The only problem I have left is the size of the Switch with the detachable keyboard takes a little more room than I like. To save some of that space I’m ditching the keyboard and printing a simple and compact stand to hold the tablet.
OpenSCAD, or Open Source CAD, is a tool for creating solid 3D models. The models are not built interactively like most people think of CAD, but are generated programmatically with a scripting language. It is very powerful, but also takes some time and patience to understand. When I am designing models like this one I prefer to make as much of it as possible configurable. This will allow anyone to modify the script with the dimensions of their tablet and print a custom model.
My design is simple, a hollow pentagon with two slots cut for the tablet. In OpenSCAD we accomplish this by drawing a 5 sided cylinder and subtracting slightly smaller cylinder from the inside. With faceted cylinders you can get very close to a true cylinder with 32 or more sides. Fewer than 16 and the sides become more distinct. We can go down to 3 sides, but 5 or 6 makes for a nicer look. I picked 5 so the front face could be parallel to the tablet and the back point would keep it from tipping over as easily. 6 sides would also have worked, but to get the same y dimension would have taken more filament to print. You can see the source code for the model on my GitHub here: Switch 11 Stand. If you need help on how to use this model, the OpenSCAD website has a lot of information.
So we have a tablet, and a stand, now we need to get Octoprint working. I chose the Raspberry Pi B+ for this because Octoprint provides a ready to run image, and the B+ has 4 USB ports. The OctoPi image can be snagged from the Octoprint downloads page. Just burn that to a microSD and boot the Pi. All the software and dependencies are included so it’s just a matter of configuring and using Octoprint. There are a couple great howtos on the Octoprint site.
Below is a photo of the 1st working iteration of the stand with the final version sitting on the printer behind it. The laptop, on the left, does not fit in front of the printer like the tablet does, and requires a constant USB connection. The Raspberry Pi is powered off the same source as the printer and handles all the USB communications, and as a bonus provides a streaming webcam so I can keep an eye on the prints.
If you have some ideas on what to build or how to utilize the Acer products in the Seize The Idea contest, head over to the Seize The Idea site and submit an entry.
[Note: This post was sponsored, and the author received a review unit of the Acer Switch 11.]