[Chiuso] Fire hazard  

Re: Fire hazard

http://wiki.e3d-online.com/wiki/E3D-v6_Assembly

Like all 3D printers, printers fitted with a high temperature all metal hotend can be a fire hazard. You are using experimental technology to heat and melt plastic, in a machine that you may have built or modified yourself, that likely does not have safety certification or significant failsafes. Fire/Smoke alarms, supervision of your printer while printing, and expertise should not be considered optional.

What is the worst case scenario?

Dead people I suppose.

Re: Fire hazard

Thanks Simon 🙂

But I want to know how people die because of a 3D printer.

A malfunctioning fan is bad. What happens when the fan dies?

Re: Fire hazard

The extruder fan? Idk. Probably a clogging extruder at some point. Not sure what happens though if the extruder temperature is set to its software/firmware max...which I don't know right now. The carriage could lose its integrity at some point without a working extruder fan.

Re: Fire hazard

But I want to know how people die because of a 3D printer.
3D printer is as dangerous as any other device using electricity for direct heating. If something goes very very very wrong, it can catch fire. Then people can die.
I know about few cases when hardware failure caused damage to 3D printer, fortunately none of them was with fire.
I never let my printers work unattended. Room with 3D printer is equipped with smoke detector and there is always somebody at home when one of printers is working. Better safe than sorry.

Re: Fire hazard

To add to this. If I remember correctly I read on this forum that the heater cartridge is not powerful enough (at 12V) to melt the aluminium of the heater block.

Re: Fire hazard

Serious enough for me to have a smoke detector/ fire alarm in my 3D printer room, and never leave home with a 3D print running. PLA can burn like a candle. Light the end of some PLA filament with a lighter and see. However the likelyhood of a fire like this with any 3D printer is rare. Lets just be careful out there 🙂 That is all.

Re: Fire hazard

I'm interested in hearing how people handle long prints. I recently did a 39-hour print. There's no way I could have done that without going to sleep or leaving the house.

Re: Fire hazard

http://www.safelincs.co.uk/fireblitz-automatic-fe36-fire-extinguisher/ 🙂 (Trying to lighten this topic a bit)

Re: Fire hazard

http://www.safelincs.co.uk/fireblitz-automatic-fe36-fire-extinguisher/ 🙂 (Trying to lighten this topic a bit)
I really thought about something like that. I'm not sure of the implementation yet.
A Box with this on top was my idea. But I'm not sure how good the tolerance are for the system. 79°C is high, but I'm not convinced it's high enough.
What do you think?

Re: Fire hazard

Use this inside printer box:

Re: Fire hazard

Yes, that's it. And at least 4 times a year whole family fire drill. Children can be trained 12 times a year.

Re: Fire hazard

Thanks for all useful information. Larger nozzle for shorter prints, mine is 60 hours with 0.4 mm nozzle. Fire alarm in printer room. In future build printer box with automatic fire extinguisher.

How flammable are different filaments? I am using PET but contemplate using ABS

Re: Fire hazard

ABS is quite flammable. However it needs to melt and boil first. Its autoignition temperature is about 460°C.

Re: Fire hazard

Going back to the OP quote:

Like all 3D printers, printers fitted with a high temperature all metal hotend can be a fire hazard. You are using experimental technology to heat and melt plastic, in a machine that you may have built or modified yourself, that likely does not have safety certification or significant failsafes. Fire/Smoke alarms, supervision of your printer while printing, and expertise should not be considered optional.

So what failsafes are actually in the printer? I only know of the Thermal Runaway error, which I believe is in case of a thermistor failure.

I found this video, which looks really promising:

I also found this video, which tells me I'm not dressing the part:

😉

Re: Fire hazard

So what failsafes are actually in the printer? I only know of the Thermal Runaway error, which I believe is in case of a thermistor failure
Software failsafe - thermal runaway protection and temperature limits.
Hardware failsafe - fuses protecting against high currents (short circuits).

BTW I would never rely only on failsafes provided by printer itself. CPU may hang leaving the board with heaters permanently on. Failsafes (if used) should work independently.

Re: Fire hazard

I found this video, which looks really promising:

My nephew is an electrical engineering student and said he'd help me figure out how to implement the device in this video. He picked out a relay that he thought would be adequate, but he said to know for sure I would need to know how much current the printer draws. Anyone have an idea? I promise I'll post some pictures with the results. 🙂

Re: Fire hazard

I would need to know how much current the printer draws.
What current are you asking about? Input current to PSU (120/230V)? Output current from PSU (12V)?

Re: Fire hazard

http://wiki.e3d-online.com/wiki/E3D-v6_Assembly

What is the worst case scenario?

I don't know how unlikely it is but here goes:

The hot-end somehow sets the extruder body (? PLA or ABS?) on fire.
The flame wicks up the filament until it reaches the full 1kg roll of filament above it.
The filament roll catches fire, starts to drip onto the printer and run over the edge of the printer and the table onto the carpeted floor, and towards the wallpaper, bookshelves or curtains.
The rest of the house follows. 😮

Re: Fire hazard

I would need to know how much current the printer draws.
What current are you asking about? Input current to PSU (120/230V)? Output current from PSU (12V)?
I believe he was talking about putting the relay between the outlet and the printer, so it would be input to PSU. Here is a possible relay he mentioned that he believes would be adequate: https://www.adafruit.com/products/3191 because it can handle "up to 10A of resistive-load current at 120VAC".