Beware your 3D printer (They can cause fires) (Page 8 of 8)

Actually - the greater majority of 3d printer fires are caused by loose electrical connections which allow arcing to occur.

RAMPS boards are famous for burning out the main power connector because over time the screw terminal loosens up (multiple heat/cool cycles)
and people do not recheck these to make sure they stay tight.

and I agree that one should not leave the printer running unattended. starting a printer and leaving the room/house - or going to bed! - is just begging for trouble.

Every printer must have over temp under temp shut down function, much like pretty much all popular printers have.
Robo3D does (thanks to community) and even chinese piece of crap named FLyingbear (agains, thanks to community)

It seems like the community is the only thing that can save your house from burning down.
Clearly printers from factory do not come flashed with firmware that prevent such thing.
Where do they even get their firmware to begin with ? Why cant they just copy from some other printer MFG and make few changes to accommodate their design ? Its all open source anyway.

Idiots.

Exactly. It does not matter what traps they put in the firmware.

The number one reason most printers go into thermal runaway is because the logic locks up.

That means the firmware is no longer running and the processor is no longer monitoring the process so the firmware is unable to intervene.

As Heartless said the best way is to watch it. Don't run it when away or asleep either. WHEN the logic locks up, not IF the system will go into thermal runaway and the heaters will continue to heat until something burns up and opens. Now how much burns down before that happens is anybodies guess.

Until they redesign boards and logic so there are watchdog circuits included that run independent of the processor and firmware there will always be a danger of thermal runaway.

Ideally all boards should have a supervisor circuit that runs independent of the processor and firmware that monitors the heartbeat of the CPU and checks that firmware is executing. IF either stop the supervisor will try to reset the board which should kill everything back to idle. If that fails it cuts AC power to the system.

This would add more expense to the boards and well we all know how most of these boards being Chinese are made as minimal as possible to save cost.

The motors are never the cause of the fires though. It's always the hot end. The logic freezes due to a power glitch, static, or any other reason. At that point temps are no longer monitored but heater is on. It will continue to heat until it, the wiring, or other burns open. That's why safeties need to run independently of firmware or processor on a correctly designed system.

You keep wording things like there are written rules to follow. Unless a product has a certification like UL or ETC,  then there are no rules and you buy it knowing that it has not met any testing other than the makers and may or may not be safe.

If you want the safest then you as a buyer look for certifications which most printers don't have. Otherwise you just have to hope be mindful of your machine.