Prusarduino - Fire protection for 3D printers

Hi friends,

When I started into the world of 3D printers, I wondered if these nice little things were safe? After all it's a heating system (very powerful though) surrounded by plastics pieces, and sometimes even closed in a woody box ^^.
So I check on internet. You can find everything on the net of course, but to be honest, accidents reported with 3D printers are very rare. Anyway, having a system that would shut down the power of the printer when smoke or high temperature would be detected, could be a great idea. I checked on internet (again eheh) and couldn’t find any very easy solution for a rookie like me. Excepted on this page: http://mkme.org/forum/viewtopic.php?f=2&t=706
The solution is Arduino! :-)
Of course these little boards are perfect to build up a full sensing system, that could power on and off a printer through a relay. It’s what they’ve done. I have to thank the MKme Lab for this very nice starting point. However, it didn’t work OOB when I used their code. So, I decided to go over it and try to make an easy solution for rookies. :-)

Here is my version.

It uses:
- An Arduino Leonardo board
- A DHT11 temperature (and humidity) sensor
- A MQ2 smoke detector (be careful! it doesn't detect flames, as you can see on the attached video)
- A 5V relay
- A power supply for the Arduino board with a switch
(around 20€)

I also designed a case for all the modules to be clipped on the printer. You’ll find here the .stl files, and among them the Arduino code to use on the board. The instructions to understand the code and do the wires connection are in comment inside the code. You can also use the pictures to help you. :-)

Here is also a video to show what it does: https://youtu.be/ErFAudwb-2c

I’ll try to upgrade everything as soon as I can.

If you find an error in the code, or have any question, please let me know. :-)

Happy printing!

EDIT: 10/11/2018: I updated the .ino file for the arduino board. There were few mistakes in the previous one that I corrected. I re-tested everything and it works fine now!!

P.S. If you like the design, please consider a small tip. It would help me buy PLA to test my designs :-)