3D Printers

[KmxSoft]

I apologise if this isn't the right place for asking for help. however I'd like to get decent advice from knowledgeable people about the following.

Having just bought a 3D printer for use in my home I'm more than a biit surprised that these heat generating devices don't seem to get much attention with respect to fire risk, and it seems even more of an issue that these devices are frequently built by DIY enthusiasts. I've built several over many years and whilst the technology for mitigating the risk of fire is available I rarely see this referred to.

3D printers contain 2 and sometimes 3 heaters. Whilst the thermocouples or thermistors control the temperatures (up to a typical max of 300 gegrees C), failure of the circuitry could easily lead to thermal runaway. I'm not sure of the thermal flashpoints which could result in fire, however some printers are housed in wooden cabinets, and there are always significant plastic assemblies which I assume could combust.

Here's the issue which I'd appreciate professional advice on...

I'd like to buy a simple fire detector which provides an electrical switch - not just a loud noise! So is there a cheap and cheerful smoke detector offering that switch? I'd use that with a relay to disconnect the power from the printer.

 I'm also up for having a canister which could flood the printer cabinet with an appropriate gas. In the good old days I'd have looked at Halon however I know that's no longer available. I did buy an extinguisher a while back containing an appropriate gas, however that depends on a glass vial breaking due to heat - the physical location of the heat path between printer and canister isn't ideal for my use. What I'd really like is a canister where the contents could be released through an electrically operated valve, possibly ported through a tube - so as a secondary question is there such a canister commercially available?

[Kinmel]

Historically 3d printers could suffer a thermal runaway, but the Firmwares in modern printers all but eliminate the problem

Modern printer systems do not only measure temperature, but also measures the uninterupted period of time that the MosFet has been passing power to the heating element.   Thermistors are constantly turning the power on and off to maintain a set temperature . When the firmware detects  an unexpectedly long continuous current, it simply shuts the MosFet down.

[KmxSoft]

Thanks for that. I agree that modern firmware deals with thermal runaway, however that assumes that the firmware and associated circuitry is operational. That's not a failsafe situation as there is no backup if the firmware fails to kick in.

[Kinmel]

If the firmware is not running then the only part of the printer that has a voltage applied to it is the small PSU.

Any PSU "fire" is going to be confined to a metal cased circuit board which at worse will release some smoke, usually the only indiction of failure is the smell.

[Noddy]

Im not sure of the prevalence of 3D printers but I’ve never attended or even heard about a 3D printer causing a fire?  

[KmxSoft]

That's interesting. I'm clearly worrying unneccessarily. Given the combination of a heat generating device and the fact that they are frequently running for double-digit hours unattended I had them to be a likely fire risk. An insurance assessor would probably have an opinion. I know there are youtube videos relating to housing 3D printers within a fire safe cabinet.

Edited July 2, 2020 by Carl
Quote removed as its a direct quote from the post above. Please see FAQ

[Messyshaw]

I have carried out fire safety work at a large industrial facility where multiple commercial sized 3D printers are in use, including those that print in metal.

No special fire safety measures such as separation, compartmentation or suppression systems were required

However, I understand that some smaller printers are left printing for many hours on complex jobs - probably not a great idea in a domestic setting if you leave it printing overnight and sleep in the same premises 

[Noddy]

I don’t know much about 3D printers to be fair but as an experienced fire investigator I’d be more concerned about the li-ion batteries and tumble dryers (and other white goods) we have in our homes.  Although I accept there are undoubtedly less printers around when compared. 

[KmxSoft]

2 hours ago, Messyshaw said:

...some smaller printers are left printing for many hours on complex jobs - probably not a great idea in a domestic setting if you leave it printing overnight and sleep in the same premises

That possibly describes most domestiic 3D printer situations where new owners buy a 3D printer without having much knowledge about the technology. From what I gather there was a sizeable rise in new owners when the corona virus lock down came in and many people had time on their hands - I know I was surprised to find the sudden loss of listed 3D printers on Amazon at the time, usually there are 10+ different models for sale and it swooped to zero overnight. No doubt many of those new owners set 3D printer projects chugging overnight.

Having a working 3D printer in a tower block is no doubt not uncommon.

1 hour ago, Noddy said:

I don’t know much about 3D printers to be fair but as an experienced fire investigator I’d be more concerned about the li-ion batteries and tumble dryers (and other white goods) we have in our homes.  Although I accept there are undoubtedly less printers around when compared. 

3D prrrinteers are a fairly recent innovation which came into existance only a dozen years ago. The early ones had a price which tended to restrict their appeal, however in the last couple of years those prices have come right down - for 200 notes you can get a decent sized printer. Some models are sub 100 pounds. I would expect, present pandoma excepted, that 3D printers will rise in prominence in forthcoming Xmas lists.

[Kinmel]

3d printers are probably the most rigorously tested consumer items in the world.

Although manufacturers take the safety and quality control of 3d printers very seriously, pre-production units are quickly put under the microscope by highly knowledgeable user groups.

One recent model did not have thermal protection turned on by default.  As soon as the usergroups recognised the problem they not only told the manufacturer, but corrected the firmware too. The rapid improvements in 3d printing is driven by amateurs and to them time and effort is of no consequence.

A desktop PC is much greater fire risk than a 3D printer.

 

[Dyson]

I attended a fire earlier this year involving a 3D printer which caused damage to the ground floor of a sizeable office block. I don’t know what make it was. 

[Messyshaw]

@KmxSoft

OK, I have done a little research tonight and come across this set up for protecting the 3D printer set up as I believe you describe that this system:

• Alerts the user in the event of smoke being detected so he can manually intervene.
• Shuts down power to the system if smoke is detected (electricity may be fuelling the fire and the system fans may encourage the fire)
• If the temperature continues to increase, automatically extinguish the fire with a clean agent extinguisher

It ain't beautiful or BS compliant, but it does exactly what I think you wanted for about £160 & electrics

Look here (or on the attached PDF below the photo) for further info (7th case study down). https://www.safelincs.co.uk/case-studies.php

Please do give Safelincs a shout as I have found them very accommodating and offer a great service (no, I am not on commission!!) 

Good luck and please do let me know how you got on !!

3-DP.pdf

[KmxSoft]

8 hours ago, Messyshaw said:

@KmxSoft

OK, I have done a little research tonight and come across this set up for protecting the 3D printer set up as I believe you describe that this system:vailable

That looks ideal. Thanks for sharing.

[Highlander]

Without the free air ventilation I bet that now gets nice and toasty