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wongarsu 8 hours ago

Closer to 200C. But the gantry constraints movement, the 200C nozzle can only really touch its holder, the print bed, the filament and some metal or silicon cleaning surfaces. None of those are flamable at those temps.

Maybe if it knocks itself down to the ground? But I worry much more about faulty wiring or stuff like that. And that's more a function of the brand and model

m4rtink 4 hours ago | parent | next [-]

It could be enough if the nozzle just stops moving while touching the model being printed - based on the type of material, it might start burning.

And if you want to be outright malicious, you can disable maximum temperature control and do the same with much hotter nozzle rammed into the model - and even print an extra burnable model when you are at it!

Or count on the power supply or the wiring catching fire instead due to overload.

colechristensen 7 hours ago | parent | prev [-]

All of the fires I've heard about 3d printing involved sketchy power supplies in some of the printers or DIY builds out there. Thermal runaway protection is really easy code to write and very common in firmware and the thermal design of the heated parts makes it hard to get there.

Not saying fires don't happen that way but let's say it's a failure mode that is a challenge to achieve intentionally much less accidentally.

Ccecil 7 hours ago | parent [-]

Thermal runaway protection does not help in certain failure modes.

Failed FET for instance. They tend to fail "on". Unless you have a highside FET shutting off the power (and that may fail too).

On my printer I have software watchdogs but I also have an entire "dumb" (no MCU) circuit that will shut off a large relay that goes to my heaters if any of it's failsafes are triggered. I have a smoke detector, secondary thermistors, etc.

There are a bit more things in the way of thermal fuses and heaters that are less likely to runaway on the newer commercial printers but I still think people need to take the risk more serious.

I have been building printers and printing since 2011 and I still prefer to not have my printer in my house where the family sleeps, even with the failsafes. It lives out in the shop with plenty of room around/above it in case of a fire.