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Personally i never leave my printers "unattended", as in i'm at home, but i don't watch them constantly when they're printing. They're in a room that is normall

Personally i never leave my printers "unattended", as in i'm at home, but i don't watch them constantly when they're printing. They're in a room that is normally closed when they're running, and is properly ventilated to the outside after. ABS is printed in the garage. I made a "better than nothing" auto off switch using an Arduino, a 230V relay, a couple of MQ2 smoke detectors, and a couple of DS18B20 digital thermometers. The MQ-2 is mounted about 50cm above my printers frame, one for each printer, connected to an arduino which has a relay controlling power to the printers. If smoke is detected, or the temperature rises above 45C, it cuts the power to all printers. The arduino defaults to off, requiring manual intervention to turn it on again via a push button. If the arduino loses power, so does the printers. It probably won't prevent the house from burning down, but in case of an electrical fire it should shut that down pretty good. The problem is the filament itself. It burns like a candle, so if the flames ever make it to the filament, it should have no problems continuing to the spool, setting the house ablaze.

vorpalhex 8y ago
Is your setup documented anywhere? I'd be interested in seeing those schematics and code. You could always mount some of those fire extinguisher balls over the printers - no need for fancy electronics. Might ruin the printer though...
- 8fingerlouie 8y ago
  I may have an old schematic in Fritzing, but i doubt it. I never got around to documenting it, but it's simple enough. My Macbook developed a "hunchback" and is currently having it's battery replaced, so i can't check the details. IIRC, i wired the relay to a default off, and there's button wired to the arduino that needs to be pushed before it turns on the relay. It then stays that way until one of the MQ-2 or DS18B20 sensors detect a reading that's outside normal operating parameters, or power is cycled. I spent quite a few hours fine tuning the MQ-2 with cigarette smoke, vape "smoke", and finally burning filament. The bad news is that the MQ-2 is rather cheap, so they need a long "burn in" period before they start giving even remotely consistent readings, and then they still vary wildly from each other. Once burn in is over though, they're rather consistent with their own readings, just don't try to match them to the neighbor :) As for the extinguisher balls, i considered it, but they looked like they'd probably destroy more than they would save. I keep my printers on floor tiles, ~60cm away from any wall, and with 160cm to the ceiling, so any small fire would have trouble spreading. If the fire was to spread beyond that, i doubt the fire extinguisher balls could save it. I was looking into CO2 cannisters, but couldn't find any that could be activated by an electrical circuit, and while i could probably design a mechanical part to activate a regular fire extinguisher, i'm not sure i would trust it.
crispyambulance 8y ago
> The problem is the filament itself. It burns like a candle... I wonder if this can be addressed by keeping a slight positive pressure of nitrogen or CO2 in the enclosure of the 3D printer?
- deleted 8y ago
  [deleted]
- nine_k 8y ago
  Filling your room with CO2 by accident won't be great either. That is, proper ventilation would be needed anyway.
  - AWildC182 8y ago
    Could do a really low volume flow of nitrogen or argon at the extruder like in welding. You'd still want some ventilation but you'd just need a tank, regulator, and tubing instead of a sealed enclosure and you'd probably use less gas. Just enough to prevent anything at the tip from burning.
    - nine_k 8y ago
      Yes, ventilation here is more like a fan in a room window than a sealed box and tubes.
bootlooped 8y ago
If you are worried about it, you can buy automatic fire extinguishers. If you hang one of those directly over the printer, I think the risk of fire spreading from that area would go close to zero.
- 8fingerlouie 8y ago
  I've made a point of buying only "quality" printers. I have a couple of Prusa i3 Mk2/Mk2.5, and an Emotion Tech Micro Delta. While they're maybe not the highest build quality, they're made from quality parts, with safety features enabled in software. Sometimes they're a bit too sensitive, like printing PETG with an open window, which will trigger a thermal runaway 85% of the times because the heater is unable to keep a steady temperature with the draft. The main "fire prevention" though is i never print while not at home, and i never print while sleeping. That of course limits the time i have for printing, but so be it. I'm thinking about upgrading to a Prusa i3 Mk3, as this supports pausing/resuming prints and cutting power between it.
ghostly_s 8y ago
What does this have to do with the topic of the article? It's about particulate emissions, not fire hazard.

vorpalhex 8y ago

Is your setup documented anywhere? I'd be interested in seeing those schematics and code. You could always mount some of those fire extinguisher balls over the printers - no need for fancy electronics. Might ruin the printer though...

8fingerlouie 8y ago
I may have an old schematic in Fritzing, but i doubt it. I never got around to documenting it, but it's simple enough. My Macbook developed a "hunchback" and is currently having it's battery replaced, so i can't check the details. IIRC, i wired the relay to a default off, and there's button wired to the arduino that needs to be pushed before it turns on the relay. It then stays that way until one of the MQ-2 or DS18B20 sensors detect a reading that's outside normal operating parameters, or power is cycled. I spent quite a few hours fine tuning the MQ-2 with cigarette smoke, vape "smoke", and finally burning filament. The bad news is that the MQ-2 is rather cheap, so they need a long "burn in" period before they start giving even remotely consistent readings, and then they still vary wildly from each other. Once burn in is over though, they're rather consistent with their own readings, just don't try to match them to the neighbor :) As for the extinguisher balls, i considered it, but they looked like they'd probably destroy more than they would save. I keep my printers on floor tiles, ~60cm away from any wall, and with 160cm to the ceiling, so any small fire would have trouble spreading. If the fire was to spread beyond that, i doubt the fire extinguisher balls could save it. I was looking into CO2 cannisters, but couldn't find any that could be activated by an electrical circuit, and while i could probably design a mechanical part to activate a regular fire extinguisher, i'm not sure i would trust it.

crispyambulance 8y ago

> The problem is the filament itself. It burns like a candle... I wonder if this can be addressed by keeping a slight positive pressure of nitrogen or CO2 in the enclosure of the 3D printer?

deleted 8y ago
[deleted]
nine_k 8y ago
Filling your room with CO2 by accident won't be great either. That is, proper ventilation would be needed anyway.
- AWildC182 8y ago
  Could do a really low volume flow of nitrogen or argon at the extruder like in welding. You'd still want some ventilation but you'd just need a tank, regulator, and tubing instead of a sealed enclosure and you'd probably use less gas. Just enough to prevent anything at the tip from burning.
  - nine_k 8y ago
    Yes, ventilation here is more like a fan in a room window than a sealed box and tubes.

bootlooped 8y ago

If you are worried about it, you can buy automatic fire extinguishers. If you hang one of those directly over the printer, I think the risk of fire spreading from that area would go close to zero.

8fingerlouie 8y ago
I've made a point of buying only "quality" printers. I have a couple of Prusa i3 Mk2/Mk2.5, and an Emotion Tech Micro Delta. While they're maybe not the highest build quality, they're made from quality parts, with safety features enabled in software. Sometimes they're a bit too sensitive, like printing PETG with an open window, which will trigger a thermal runaway 85% of the times because the heater is unable to keep a steady temperature with the draft. The main "fire prevention" though is i never print while not at home, and i never print while sleeping. That of course limits the time i have for printing, but so be it. I'm thinking about upgrading to a Prusa i3 Mk3, as this supports pausing/resuming prints and cutting power between it.

ghostly_s 8y ago

What does this have to do with the topic of the article? It's about particulate emissions, not fire hazard.