Arduino Watchdog Sniffs Out Hot 3D Printers

We know we’ve told you this already, but you should really keep a close eye on your 3D printer. The cheaper import machines are starting to display a worrying tendency to go up in flames, either due to cheap components or design flaws. The fact that it happens is, sadly, no longer up for debate. The best thing we can do now is figure out ways to mitigate the risk for all the printers that are already deployed in the field.

At the risk of making a generalization, most 3D printer fires seem to be due to overheating components. Not a huge surprise, of course, as parts of a 3D printer heat up to hundreds of degrees and must remain there for hours and hours on end. Accordingly, [Bin Sun] has created a very slick device that keeps a close eye on the printer’s temperature at various locations, and cuts power if anything goes out of acceptable range.

The device is powered by an Arduino Nano and uses a 1602 serial LCD and KY040 rotary encoder to provide the user interface. The user can set the shutdown temperature with the encoder knob, and the 16×2 character LCD will give a real-time display of current temperature and power status.

Once the user-defined temperature is met or exceeded, the device cuts power to the printer with an optocoupler relay. It will also sound an alarm for one minute so anyone in the area will know the printer needs some immediate attention.

We’ve recently covered a similar device that minimizes the amount of time the printer is powered on, but checking temperature and acting on it in real-time seems a better bet. No matter what, we’d still suggest adding a smoke detector and fire extinguisher to your list of essential 3D printer accessories.

23 thoughts on “Arduino Watchdog Sniffs Out Hot 3D Printers

  1. Neat project. I’d like to see something similar built into the firmware to control a relay for power as most firmware already detect thermal runaways but as mentioned in the project article cant do anything when mosfets fail closed.

      1. A thermal fuse could easily stay cool while the printer bursts into flames. If the current doesn’t spike, but remains inside of specs, the components on the board may still overheat (if the system was built by cutting corners).

        1. I was replying to thermal runaways due to mosfets failing failing in the on condition. Using thermal fuses on the heated and hotend (heatsink) can easily prevent thermal runaway in this condition. I do this on all my printers.

  2. nicely done project.

    that said, might be a bit less complicated to just pull the bargain basement probably-fake MOSFETs from your board and replace them with parts sourced via more reliable channels, that have low enough Rdson that you’re not risking failure in the first place. the last time i looked at the schematics (years ago), even reputable RAMPS boards were allergic to spending the $1 necessary to get a power FET actually intended for continuous duty at 10-20A.

  3. Just curious why manufacturers (at least ones built / designed in NA or Europe) don’t include thermal fuses in critical parts like the hot end and heated bed. They seem to be standard / safety required equipment on just about anything else I buy that makes something hot on purpose.

    1. Ultimaker here. We investigated thermal fuses during Ultimaker 2 development.

      Conclusion, due to the small amount of mass we are heating up, and the large temperature range we operate at, any location where we can fit them, they will trigger too soon or too late. Instead, we designed the whole thing to just get hot (~500C), not go up in flames, when you have a thermal runaway.
      (Next to the usual firmware safety checks)

        1. A common way of failure is also that the heating element is pulled out of the hot end by solidified exturded plastic when it gets entangled by the wires. The fuse will stay in the hot end and do nothing in that case.

          However, the uC can easily (and often does) detect that the heat input does not correspondent anymore with the hot end temperature and can take appropriate action.
          This is a good example where smart software is better than hardware.

          1. This is one of the protection items that is often disabled (for whatever reason…) in many of the Chinese printer kits that are hitting the news for their tendency to go up in flames.

            Thermal runaway protection is great, if it’s turned on.

    1. Far too common lately in my book, it’s bad for the whole market. And these are the fires you hear about. Not everyone shouts online when their printer catches fire. Especially if the damage is local and the supplier replaced the machine.

      Don’t know how many other manufactures give off a declaration like this:
      https://ultimaker.com/download/68213/Declaration%20of%20safe%20unattended%20professional%20use%20%28UM3%29.pdf
      But I think it’s important that printers match up with expectations. With 50+ hour prints, you should expect printers to run unattended.

    2. As Daid303 said, far too common, and of very high risk. I alresdy know how f offices burning (no big damages luckily). And know of machines that where discovered early enough. Semiconductor are not the only parts to check, connectors are critical.
      I think a proper failure root cause and redesign is better, as ultimaker seems to have done, than relly on another system that will most likely can fail). Interesting design any way.

    1. My solution was to buy a reputable (still Chinese) power supply, a British control board, as well as a British extruder and hot end, to replace the questionable bits in a Chinese kit.

      E3D and Duet3d, with a MeanWell PSU, and I haven’t had any concerns as to safety or reliability.

      There are surely other reputable options out there, but the “nothing matters but the cheapest price” design philosophy of many of these kits does not inspire any confidence as to their safety.

      The MKS control board that came with my current printer has never been out of the box, other than to briefly look at it before the frame was assembled.

    1. Obviously you haven’t been paying attention. Hackaday has already documented a number of printer fires, as well as the causes.

      You should probably do a basic search on the site before making comments like these.

  4. If I ever bother to get around to building or acquiring a 3D printer, I think I shall place it inside a disused scrap oven. Then it is inside an insulated metal box with a window so I can watch in awe as the magic smoke consumes all.

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