Most of the 3d printer firmwares can detect heat spikes and stop heating the extruder to prevent fire and you can control your printer's power with rpi with a simple relay circuit. You can also setup a bot with camera to alert you via mail/message/telegram if there is a fire risk. These are the common precautions I have seen people take.

that's a very good point. Especially because there is a large community of hackers that love tweaking their printer (I'm one of them). Things like using the wrong voltage on a hot bed or fan can start a fire.

Here is an example of what this guy had to go through: https://www.thissmarthouse.net/dont-burn-your-house-down-3d-...

I agree, I use octopi but mainly because it is convenient and not to run it remotely.

I'm thinking of eventually enable remote printing though (just to be able to perform long prints), but I will have some safety measures installed before that. All of the below is probably mandatory for me.

* A webcam that I can watch from wherever I am (mobile and browser). Also with audio so that I can listen in on it. I think it would be possible to have an automatic system to listen (or watch) in on the printer to hear anomalies - but I will not have the energy to pursue that.

* I will be able to shut down the power via internet.

* Perhaps automatically shut down printer and then cut power if internet connectivity is lost - preferably with sms notification.

* A smoke alarm that automatically cuts power (will most likely be software controlled though, so not foolproof)

* A heat activated fire extinguisher (haven't done research on it yet but exists quite a few, popular for caravans etc.).

* Decent printer with good track record (prusa), and all the automatic protections enabled (temperature sensors giving up etc.)

I have not yet decided if the above provides a satisfactory level of assurance that nothing will go wrong. I know that just the webcam will provide immense ease of mind - but that is just me being human.

OctoPrint user here. I'm surprised that unattended printing is somehow supposed to be the primary use case for OctoPrint.

For me the point of the software is not to leave a printer unattended for long periods of time. To be honest, I don't see how OctoPrint is fundamentally different from the printers' physical panels in this regard: my printers did not come with deadman switches either! If I wanted to start a 2 week unattended megaprint, I could do that from the standard printer panel as well.

The draw of OctoPrint comes from the fact that it's a standardized and networked UI. It allows you to upload files to your printer, manage its settings, take a video of the print. It's a deluxe firmware.

I mostly use OctoPrint because it gives a nice web based interface that I can access from more than just the 1 PC that used to be connected to my printer. Being able to send jobs to the printer via the network is also pretty great.

I was touring one of the 3D Printer manufacturers when they were first setting up, in little more than a garage. I'm not mentioning names because, honestly, it doesn't matter. But I remember it being said "We aren't running the printers unattended until we've gone a full day without one of them catching on fire... I have no reason to expect that is still the case, but it's a funny memory.

I always think how i would feel about a known fire in my house. Would i leave my fireplace unsupervised for a longer period? Definitely not, and that is the one place that should be fireproof.

I use my Octoprint mainly for three things:

1: Controlling the axis for manual bed leveling (yes i level manually)

2: Upload the gcode files to octoprint (no fiddling with micro sd cards)

3: Watching the picam. So i can sit in another room, but so close to hear if a motor jammed or something else.

You can also get a small automatic fire extinguisher like they have for grow rooms and over stoves to help mitigate. Having that in an enclosure with some leds and a webcam would be a decent mitigation. Checking in on the print every now and again is a good call too.

I've heard that purging the 3D printer with e.g. CO2 gas is something that you can do to improve layer adhesion. It should be sufficient to prevent fires also? Seems most plastics have a limiting oxygen concentration of around 16%. Purging from 21% down to, say, 15% requires that one adds 40 L of CO2 (at STP) to dilute a 100L chamber. Your typical 2.6 kg small CO2 bottle that people use for home-brew beer kegs would last for at least 35 fillings.

interesting thought but it's hard to seal up a vessel for any length of time. you could perhaps do a positive pressure vessel that slowly leaks from inside to out. (this is a common tactic in clean rooms with purified air a psi or two more pressurized than the hallways so the clean air always flows out to the hall.) not sure what the effects of leaking CO2 into your room would have though.

I wonder when we will see the first 3D printer that can validate what it is printing via some camera and image recognition software.

And maybe even correct errors it made a second ago ;-)