Purpose:

3D printing filament sensor meassuring serveral aspects to pause prints before they fail.

• Pause print by observing a rotary encoder meassuring filament movement (lack of movement or wrong direction).
• Also pause by ovserving a load cell meassuring extruder pulling force on the filament (too much or sudden loss of force).
• Also observe another load cell meassuring how much weight of filament is left on the spool and warn if it's not enough.

License: AGPL 3.0

Status: WORK IN PROGRESS - unfinished (software stable, documentation in progress, hardware being cleaned up for release)

Attribution:

This plugin is based on https://github.com/MoonshineSG/OctoPrint-Filament (AGPL 3.0 license) The Hx711 code is based on https://github.com/tatobari/hx711py/ (Apache 2.0 license) Licenses are deemed compatible: http://www.apache.org/licenses/GPL-compatibility.html

Hardware:

The hardware is currently being developed here: http://marcuswolschon.blogspot.de/2016/06/ultimaker-ii-filament-sensor-and-remote.html

Installation:

 /home/pi/oprint/bin/pip install --upgrade pip
 /home/pi/oprint/bin/pip install numpy
 sudo chmod a+rw /dev/gpiomem
 /home/pi/oprint/local/bin/python setup.py install && sudo /etc/init.d/octoprint restart && tail -f /home/pi/.octoprint/logs/octoprint.log

alternative for development (no reinstall on every change of the source code):

 /home/pi/oprint/local/bin/python setup.py develop && sudo /etc/init.d/octoprint restart && tail -f /home/pi/.octoprint/logs/octoprint.log

Settings are in the Octoprint Settings menu. Pins are in BCM numbering.

• odometry_pina - first pins for the rotary encoder, meassuring filament movement.
• odometry_pinb - second pins for the rotary encoder, meassuring filament movement.
• odometry_min_rpm - the filament wheel must have turned this many times before the odometry sensor will ever generate an alarm
• odometry_min_reverse - the filament wheel must have turned this many in reverse times before the odometry sensor will pause the print
• odometry_timeout - if no movement is detected for this many seconds, pause the print
• odometry_circumfence - circumfence of the filament wheel on the rotary encoder in meter
• center pin of the rotary encoder is connected to GND, pina and pinb are pulled up by the Raspberry Pi
• odometry_bound - time in milliseconds to debounce the odometry pins
• odometry_inverse - inverse the detected direction of the rotary encoder. Reverse movement is a cause to pause the print. ("False" or "1")
• force_pin_clk - CLK pin of the Hx711 board for the load cell meassuring the filament pulling force
• force_pin_data - DATA pin of the Hx711 board for the load cell meassuring the filament pulling force
• force_maxforce - exceeding this value (after scale and unit are applied) is considered excessive force and pauses the print
• force_minforce - less then this value (after scale and unit are applied) is considered a (sudden) loss of pulling force and pauses the print
• weight_pin_clk - CLK pin of the Hx711 board for the load cell meassuring the (remaining) weight of the filament spool
• weight_pin_data - DATA pin of the Hx711 board for the load cell meassuring the (remaining) weight of the filament spool

API

(work in progress) An API is available to check the filament sensor status via a GET method to /plugin/filament/status which returns a JSON

Note: Needs RPi.GPIO version greater than 0.6.0 to allow access to GPIO for non root and chmod a+rw /dev/gpiomem. This requires a fairly up to date system.