Filament runout sensor for OctoPrint

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Joined: Sat Mar 11, 2017 11:23 am

Filament runout sensor for OctoPrint

Post by zorrobyte » Sun Mar 12, 2017 9:57 pm


I've been considering building a filament runout sensor and have this one in mind:


This works with an Octopi and can pause the print if the filament runs out. Unfortunately it doesn't have dual extrusion support, but I may submit a PR if I have the free time: ... d/issues/3

I see that Marlin has FILAMENT_RUNOUT_SENSOR support as well, although since I'll be using OctoPi - no need to tweak my Lulzbot Marlin config (and pull my hair out when I change toolhead and reflash).

It'll be a few weeks before I build one, but will share my thoughts here.

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Joined: Sun Feb 12, 2017 8:57 pm

Re: Filament runout sensor for OctoPrint

Post by sneaks » Mon Mar 20, 2017 7:53 pm

Hey Zorrobyte, You could actually put two of my sensors in parallel and it should work. The only concern is your printer wouldn't be able to determine which filament is actually out. It would just know it needs to pause your print and run some gcode. Worse case scenario it unloads both filaments and you have to reload both. Small concern in comparison to a failed print.

It is at least something to get you up and running until a plugin can be updated for dual.

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Joined: Mon Mar 13, 2017 4:52 pm

Re: Filament runout sensor for OctoPrint

Post by DCWGeoff » Tue Mar 21, 2017 3:01 pm

Just what I was thinking of building after having a near catastrophic printer failure with during an out-of-filament condition (the PTFE guide tube went wandering and was pulled into one of the holes in the side of the large gear on the extruder).

Any idea how the sensor works on transparent filaments such at T-Glase? I would expect some attenuation of IR with T-Glase, as well as fanning / dispersion of the IR beam, which might be enough to trip the sensor.

Otherwise, I was thinking of something like this but using a roller-type microswitch to detect filament-out, and a second microswitch to detect unusual tension due to a spool jam. Any sensor setup like this needs to be reliable both in terms of false positives and false negatives.

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