Thermal Run Away, Printer caught on fire.

<p>Bought the new MK3 extended model and everything was working good for about one month. Inserted new filament and clicked extrude and turned around to do some Christmas shopping online and after a while i heard a horrible snapping or popping sound which was the filament boiling inside the hotend and a small fire started at the nozzle, thank god i was around to catch it before well… who knows? it could have been very bad. anyways i contacted support and they asked for pictures which i did, one of the hotend and the burned and melted fan shroud and another of the tiertime program because it now reads some very crazy numbers for the temps of the hotend and bed. mind you i dont have a heated ben but it was reading -50c for hotend and 1989c for the bed. needless to say i have a $500 dollar paperweight but the worst part is now support will not return my emails.</p><p>I have no idea if just a new heater and thermistor cable would solve the problem but to be honest i could never leave the printer alone again which is not practical so i just want to return it at this point which maybe why they are avoiding me? at this point i am getting very upset and need your help Jason or Joshua. please do not ignore me. </p>

<p>Hi</p><p>This sounds very Bad… :(</p><p>Can you share the pictures of your printer?</p><p>I have some ideas of the failure:</p><p>- Thermal sensor came out from the heater block there is no good thermal contact so CPU tries to reach the requred temperature therefore overheat the Extruder.</p><p>- Bad electrical connection of the extruder flat cable cause bad thermal sensing…</p><p>- Heater FET shorted on the mainboard therfore heater always on</p><p>- Software bug…</p><p>Do you have an electronic multimeter which can measure resistance / voltage?</p><p>If yes I can help to find the real root cause. by the way I am also curious I also have one MKIII pinter.</p><p> </p>

<p>I would love your help. Could we do it over the phone? I could give you my email but im not sure about on here and yeah i got a multimeter and know the basics.</p>

<p>I try to write you a private message, here but this is not work at all.</p><p>So my proposal to let’s continue in the facebook group:</p><p></p><p>Please rise up this topic there and I will write to you again. We can chat as well.</p><p>Péter</p>


Sorry for not able to provide a satisfying solution in time.

But dont worry, we will follow up your support ticket and get it fixed ASAP.

<p>i would very much appreciate that Jason. i have emailed you many times over the past week and need to return this printer for a refund. its a nice printer but i could never leave it alone now.</p>

<p>Hi Sealight, I refuse to use facebook and jason wu is now speaking to me. i might get this solved now but if i dont i will post my email here and then a phone number from that or something. tyvm bro</p>

You are welcome, I hope your printer getting work again. It is nice printer. But is still curious what went wrong I dont want to monitor my Cetus...

This is the reason some homeowners insurance policy will not cover an incident that is caused by 3D printers. I would suggest hanging automatic clean extinguisher over the printer. it really gives some peace of mind.

@Jason-TT do tiertime printers have thermal-runaway protection? Do they have watchdog timers enabled in the micro controller?

The printers currently do not have timers for thermal runaway.
All its protective mechansim are based on the pt100 thermistor. If the thermister some how short circuited or the MCU broke, there could be uncontrolled heating.

Thanks for being honest about it.

The printers currently do not have timers for thermal runaway.

May I ask, why not have it? It is a basic safety feature all the printers out there running open source firmware have. Its every home owners nightmare to have a fire. I’ve nearly had a printer burn down on me years ago, before the open source firmware had thermal safety features enabled. Luckily I was around before there was any damage to the room when it caught fire. I take this very seriously.

I’ve just checked the datasheet for the PT100. If there is higher resistance, the temperature is considered lower. So if the wiring is failing and has higher resistance, it would be possible this is detected as lower temperature which could lead to overheating. Would you agree?

If his hotend read -50c and that caused overheating … perhaps some more safety checks are required to check if values are sane.

What are your thoughts on the matter?

No update on this?

No plans to improve?

No plans to fix the lack of watchdog timer or thermal runaway detection in software?

We will add more safety features in the future.

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Time frame please. Is this not a priority?

How long will we have to wait? Over a year? (like with the wall/infill gap issue?)

I run my printer for days at a time often while I’m away. I’m sure other businesses who use these machines can’t always have someone babysitting the machine for a whole 24 hours either. This is a serious concern for me.