3D printing is a Fire Hazard!

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neep
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Joined: Sun Jan 04, 2015 12:45 pm

3D printing is a Fire Hazard!

Post by neep »

After leaving a print unattended for about an hour I came into my lab to find my Felix 3.1 with a hot-end completely separated from the PEEK part. Apparantly it had gotten jammed, and the guide wheel grip was strong enough to have the PLA filament push out the hot-end straight out.
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I am apalled that this could happen and that there isn't any sort of safety mechanism in place to stop this. The hot-end was being dragged along the platform and the print, which subsequently was melting so much it discolored and leaves me to wonder if the whole print could have caught fire, with disastrous outcome. In this case, the max temperature would have been limited to 195C, but what if the thermistor or the heating element had been dragged out as a result of this event, and the temperature could have become higher? I don't want to imagine the nightmare that could have come of that.
IMG_0002-20160415-4.jpg
This experience made me acutely aware of the very real fire hazard that an FFF 3D printer poses, and had me looking into my insurance policy. Then I started googling for experiences of others in this regard, and found some horrible stories. Someone had his house burned down and lost a pet. Another had his entire printer go up in (2 feet tall!) flames.

I think it's becoming time that printer manufacturers think and do more about safety of their products. Not just because I can see liability law suits happening in the medium term but mostly because it's the right thing to do. Having a smoke detector that not only can trigger an extuinghisher but most importantly shuts off the power to the entire device is paramount, IMHO, and doesn't have to cost much at all.

You don't have to look much to find some of the examples I mentioned. Just google for "3D printer fire hazard" and you'll see some very frightening posts and pictures. The actual causes can be many. Simple short circuit, heating element separation, thermistor problems, etc. This is a machine with moving parts that hold wires that connect to relatively high current power sources. Things can and will go wrong, either mechanically, electrically, or even the software can have bugs and indirectly cause much destruction.

I believe something like this should be a standard feature on any FFF 3D printer:

https://www.kickstarter.com/projects/10 ... s/comments

Thoughts? Discussion? I think it's high time.

Neep
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kerog
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Post by kerog »

What firmware version were you using? From 0.92, there is a heater decouple shutoff. Sounds like you had a heater decouple, overheated, and the peek dropped off. Can't see how the jam you were describing could have done it by itself.

Totally separate from the rest of your point, though.

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gfeliksdal
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Post by gfeliksdal »

Hello Neep,

Sorry to hear this happened to your printer. Indeed curious to hear which firmware version you have. To let you know that we take safety serious. We have implemented several safety features to prevent burning from firmware 0.92 onwards. After testing several worst case scenarios, we urged the firmware developer to implement the following features.

Heater decoupling test. If the extruder heater cannot increase 1 degC in temperature at full power within 15 seconds, it will shut itself off. (60seconds for the heated bed). This prevents fire-hazard in case when thermistor and or heater drops out of heater body. The most dangerous case is when the heatercartridge falls out of the heater body, it will become red-hot and reach temps above 400degC.

Temperature variation tests
If the temp cannot hold its temperature within 15deg of its target temperature over some time period, it will also shut itself off.

In your case although the temperature was hot enough to melt the peek isolator, it would fortunately not be a direct firehazard. The real firehazard is when the heater cartridge falls out of the heater body and touches some of the plastic parts.

Besides these safety features we also not recommend to leave the printer unattended for very long periods of time. If you do it, it is recommended to leave it in a properly conditioned room.

Stop Fire
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Post by Stop Fire »

Yes, the possibility of 3D printer catching fire also depends on the version of firmware that is installed ! More recent firmwares are more advanced and have the additional protection measures – like against a thermistor coming off place. For example, below you can find a commit message 43c298a (dated Jun 30 2014) from a Marlin Firmware repository. My cheap Chinese 3D printer (with Atmega 1284P) had a slightly older firmware version installed, so I had to update its’ firmware to enable this “Thermal Runaway Protection”! Always update a firmware of your 3D printer!!!

/*================== Thermal Runaway Protection ==============================
This is a feature to protect your printer from burn up in flames if it has a thermistor coming off place (this happened to a friend of mine recently and motivated me writing this feature).

The issue: If a thermistor come off, it will read a lower temperature than actual. The system will turn the heater on forever, burning up the filament and anything else around.

After the temperature reaches the target for the first time, this feature will start measuring for how long the current temperature stays below the target
minus _HYSTERESIS (set_temperature – THERMAL_RUNAWAY_PROTECTION_HYSTERESIS).

If it stays longer than _PERIOD, it means the thermistor temperature cannot catch up with the target, so something *may be* wrong. Then, to be on the safe side, the system will he halt.

Bear in mind the count down will just start AFTER the first time the thermistor temperature is over the target, so you will have no problem if your extruder heater takes 2 minutes to hit the target on heating.*/

Hugues
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Post by Hugues »

That sounds like something that should be added to our printer,

would like to hear from Felix about this !
Hugues
Regards from Switzerland

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gfeliksdal
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Post by gfeliksdal »

Hi Hugues,
This has been implemented for about 3 years now. Starting from repetier firmware 0.91. At the moment people updated their firmware, we had quite some people with bad thermistors which required a replacement for their printer to work properly. There are two safety mechanisms:
DEF: thermistor decoupled, this will popup when the thermistor signal falls out of range.
DEC: Heater decoupled, this wil popup when the heater is not able to heat the hot-ends one degree C within 15 seconds. or the bed 1 deg C within 60seconds. It will also detect if the temperature remains stable within 20degC

This fix covered the most dangerous situation where the heater cartridge falls out of the heater body when it was not mounted correctly. If this happens the heater cartridge can easily get to a temp of 400 degC, which obviously is not very safe.

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