Using Octoprint with the C3D Mini

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    So I run Octoprint on a Raspberry Pi to control my CR-10 3D Printer. It offers some features like a webserver so I can control it from any device on my network, as well as outside my network. It allows gcode to be uploaded to the printer’s onboard micro SD card via network (drag and drop in the browser*). It gives the USB webcam a URL. And it does way much more!

    I want all of that for my laser too! I figured it may be pretty simple considering i use Pronterface to test and control the laser. I mean Gcode is Gcode after all right? 🙂

    Ray told me that Jim Fong did this so I contacted him. I now have the info! I am going to implement this ASAP and I will update you when I get it running!

    DISCLAIMER: never run your laser unattended. use this at your own risk.

    A big thanks to Jim Fong for these instructions:

    Using Octoprint to control a Laser Cutter

    Requirements (as tested)
    Raspberry Pi3
    Cohesion3D mini with Smoothie Firmware

    Download lastest Octopi for RaspberryPi image from

    Install Octopi disk image on a SDcard. I used Etcher,

    Follow the Octopi Getting Started instructions to configure Networking and System Password

    Plug in the Cohesion3D board to one of the Pi3 USB ports.

    Plug in the SDcard in the Pi3 and boot.

    Using a web browser, connect to the Octoprint server using the IP address displayed on screen. You will need to hook up a monitor to the Pi3 HDMI to see the IP address.

    At this point, you should have Octoprint running on the web browser. If not, see this video for more help

    Octoprint configuration
    The smoothie serial port connection will be /dev/ttyACM0
    Baudrate AUTO
    Printer Profile Default

    You will be able to jog the laser using the Control window however the HOME button will not work correctly.

    Some additional Octoprint settings are required. The Settings page is accessed by the wrench button upper right hand corner of web page.

    Select Gcode Scripts and add M5 to the “After print job is cancelled” window. Add this as the first line item.
    To home laser printer when connected, add $H to “After connection to printer is established” window.

    To add a working Home Button, you will need to install the Custom Control Editor using the Plugin Manager. Create a new Button control and add $H in the command box.
    See on how to create this new Home button.

    I used Lightburn to create the Laser gcode. Before you save the gcode make sure Start from current position is selected. You can use Octoprint Jog buttons to postion laser head
    and when the gcode is run, the laser will start from that position. Use the Octoprint Upload button to copy the gcode file to the Server. Gcode file must have .gcode extention.
    To start a Laser Job, click on a uploaded gcode file and select print.

    Jim added:

    I only did a few test laser scanning cuts. Octoprint serial feed isn’t as fast as LightBurn usb serial. You may see pauses while laser scanning. There is a Octoprint setting to ignore the serial “OK” and it will feed the gcode faster. Since I only did limited testing you may see some issues.

    Octoprint built in home button sends to wrong gcode command. I think it is G28 when smoothie laser requires G28.2. Let me know if you find a way to change that. I made a new home button to get around that issue.

    *Note on drag and drop provided by Ray:

    While you can upload via octo to the memory card in the C3D (by dragging your file onto the right half of the Octoprint window) this is slow. By dragging it onto the left half you are actually uploading to the Octoprint installation (i.e. the card in the pi) and that seems to be what is actually happening here (and what you should be doing).

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