OctoPrint on x86

A few years ago I began a journey into 3d printing. It has been a wonderful hobby for me and I have learned a lot about the world of manufacturing and "making". Like many beginners, I began with a budget printer from Creality. These printers are inexpensive, insanely modifiable, and have a ton of community support. I have been happy with my choice but there is one thing that I have always disliked about it: the SD Card shuffle.

Enter OctoPrint

Most budget printers do not have network connectivity. The main mechanism used to transfer files to them is via an SD Card. This "shuffle" always rubbed me the wrong way. It is tedious and error prone and I knew there had to be a way to simplify my workflow. This is where OctoPrint comes in. OctoPrint is a wonderful, free, open-source web UI for 3D printing. Among the many things that OctoPrint provides, it allows printing from a network connection.

The Raspberry Pi Problem

OctoPrint is typically installed on a Raspberry Pi; a low-power, low-cost, Arm-based, single-board computer. An image called OctoPi exists for this very purpose. It is almost a turn-key solution and can have OctoPrint up and running quickly. This is the option I wanted to use, however, I didn't own a Raspberry Pi.

It turns out that sourcing a Raspberry Pi is challenging in 2023. The Raspberry Pi was a very economical option before the pandemic and you could secure a board capable of running Octoprint for less than $50. Those boards are now well over $100 and typically out of stock. That's unfortunate, but I had a solution!

The Intel Option

I have an Intel NUC mini-PC that has served several purposes for nearly a decade. It is no longer usable as a primary computing device but has all of the features I need to build a capable OctoPrint server, namely WiFi and a couple of USB ports. The NUC will consume much more power than the Raspberry Pi and take up more space on my workbench, but up-cycling this device feels like a great choice.

OctoPrint Installation

Installing OctoPrint is straightforward and there is nothing specifically different when installing it on x86. This OctoPrint Forum post is a useful guide and worked to get me up and running.

USB Cable Hackery

OctoPrint communicates with my printer via a micro USB port on the main board. I used a standard USB A to micro cable to connect my NUC to the printer. At this point, I found my printer's board in a powered-on, partially booted state which prompted me to take a brief journey into the USB specification.

USB ports, regardless of their connector type (A, micro, mini, etc.) provide 5 volts of DC power. Most cables will happily pass this voltage through to a recipient. This is why we don't have to use external power for low-power devices like webcams and some hard disk drives. Unfortunately, the Ender3 V2's main board does not operate properly when this voltage is applied and we need a way to disable it.

USB cables separate power from signals using different wires. I saw two options to prevent my Ender from receiving the unwanted 5 volts: cut the power wires on the cable or cover the connector pins providing power. I chose the latter option because it seemed a bit cleaner than opening the USB cable's shielding and cutting the wires. I used a bit of tape to cover the USB A's pins to prevent them from connecting with the port's power. This worked as expected and the printer's board no longer partially booted.

Serial Connection

Now that the power is no longer powering our main board it is time to move on to enabling the serial connection that the USB cable provides. The OctoPrint web UI provides a dialogue to configure the serial connection to the printer. I knew I was using /dev/ttyUSB0 and my baud rate but was simply unable to connect.

Undiscouraged, I decided to manually connect to my /dev/ttyUSB0 device using the screen utility. If the connection is successful, you will receive G Code in the terminal. I was only able to connect and receive G Code when I ran screen as the root user. This means that the user running the OctoPrint service did not have permission to access the /dev/ttyUSB0 device. You can enable access, on Ubuntu 22.04, by adding the user running OctoPrint to the proper groups.

sudo usermod -aG tty,dialout $USER

This will add your user to the proper groups for access to the /dev/ttyUSB0 device. Change the $USER variable if you are running OctoPrint under a different user.

The Long Awaited Wireless Print

Now with everything set up, I can slice, upload my G Code, and begin a print directly from my computer. I no longer have to shuffle SD cards or leave the comfort of my desk; my workflow is beautifully simplified. OctoPrint is a high-quality piece of software providing a wealth of capabilities. Its ability to run on low-power hardware makes it perfect for installing on outdated hardware like my decade-old NUC. I highly recommend testing OctoPrint and if you like it, contribute to its development.