Beware your 3D printer (They can cause fires) (Page 5 of 8)

Looks like it is off (commented out) by default.

One more thing to worry about, thanks!  8*|  Condolences to SkyMiner, that had to be pretty horrific!

So I just ordered a Kidde PI9010 [See below, should have ordered PI2010] dual-mode smoke detector and SM120X relay module for $30-ish.  That and a relay to drop out on alarm activation ought to cover the starting-to-smoke case.  Plus it has a 5V output which I can probably connect to my Raspberry Pi to have it text me (and interface to my fire alarm system).

I'll probably add the http://www.amazon.com/10Pcs-Celsius-Cir … B00H8SKNFO to my E3D hotend if I ever get it installed to cover the hotend overheating case.

But I think SkyMiner's point wasn't "OMFG, don't print unattended!", but "In the real world we need our 3D printers to be able to print unattended without burning our houses down."  You can espouse "Never print unattended" all day long, but when I've got a 28 hour or 54 hour print job, what am I supposed to do?  And if I have to check on  a printout constantly, then the cost of my objects just went from pennies to tens of dollars.

And while we need firmware, that's not going to solve every problem.  As a computer engineer I can tell you that hardware's going to fail (FETs stuck on), and firmware's going to crash (leaving heaters in whatever state they were in), so we need the mechanical engineering of the product to provide fire safety, plus electrical failsafes should anything go wrong.

w_smith, your line of thinking is all fine and good for the Makerbots of this world - the companies producing fully assembled printers that are unlikely to be modified by an end user.

The problem comes when kits are assembled by folks that may have never stripped a wire before. The safety of such a machine is largely a function of the end user's assembly skills, creating the impression that unattended printing is safe would be irresponsible.

Also, the "well some prints take 24 hours" line of reasoning is a not a great one. If you're pulled over for doing 120mph on the highway, it doesn't matter that it's a long way from LA to NYC - what you're doing is unsafe and you're getting a ticket.

If you want to take countermeasures to improve the safety of your machine, that is a good thing! But do not be disillusioned. There are only two truly safe ways to print: with the printer in a metal box, or attended (human in the same room).

I would think a fire rated chemical cabinet (the big yellow ones) would be the best option for unattended printing. One could also rig up a fire extinguisher (Halon) to a relay that is tripped by the smoke detector. Also have the smoke detector trip the power relay. Another relay could be used externally to drop off power if internet connection was lost, not allowing you to keep an eye remotely on your print. A lot of hoops to jump through, at that point you might want to look at leasing a commercial printer, or picking up a second hand commercial printer if your doing multi day prints.

Automatic halon suppression: $185
http://www.amazon.com/Fire-Fight-Produc … atic+halon

Fire cabinet: $515
http://www.amazon.com/gp/product/B001Q8 … _i=desktop

$700 bucks and im pretty sure you would be safe to print as long as you like.

I could have possibly started a fire last night. I replaced one of the stepper drivers on the Sanguinololu that came with the SD2 I bought off a guy here and the extruder MOSFET decided its life was over. Not sure how it happened. Anyway, after realizing the extruder was heating I noticed my volcano reading a temperature of 480C, so the thermistor is definitely shot and I'll be wiring in my original RUMBA...

Remember, MAXTEMP doesn't mean much if the board MOSFET goes, which, once again, is a great reason to never print unattended. FET failure can happen at any time and without warning. Watchdogs, fuses, logic, etc. cannot prevent disaster in this scenario. Only human intervention can.

Sounds like a conversation I recently had

@Jagowilson- I am glad you caught it in time. And you hit the nail on the head: no preparation compares to human intervention.

I generally will let longer prints go unattended, in the sense that they are running while I'm not paying attention to it. Usually I'm in the same room or, barring that, other people are in the room with it (sometimes I print in the living room, sometimes by my computer desk). I basically use the same sense I use with an oven or a toaster. Gotta keep checking on it and make sure nothing is wrong and don't leave it running when nobody is there to keep an eye on it.

Isn't this what the kickstarter Smoke Signal did? Can't figure out how to order it.

glad you caught it in time with no major damage, but kinda looks to me like there are some non-factory wires there? the fan is obviously not a factory install but what is with the twisted up ends on the red/burned wires at the bottom? I would say those are the source of your problem.

If the connection of the power wires in the terminal block isn't very good, it causes extra resistance and heats up.  I had the power block on my Sanguinololu melt once or twice because one of the wires had pulled partway out after I turned the printer around.

You shouldn't ever need to cool wires or terminals. If wires or terminals get warm/hot, they are underrated for the job they're performing.

um, yeah...if the bare ends of those wires were exposed, that is definitely the source of the problem.

and I am not a big fan of  those plastic covered crimp connectors, either - have seen far too many fail and cause problems because they weren't crimped well enough.
Heat-shrink tubing is a far better alternative IMHO - twist the wires together tightly & securely, slide heat-shrink over the connection - make sure there is a good overlap of existing insulation on each end and heat to shrink tight.