Anet A8 SAFE mod

I'm working on an automatic fire alarm for 3D printers. Not to the alarm, but ensure automatic shutdown of the printer if it overheats.

The biggest "danger" is the thermostat which is located in a small hole on the print head (Heatblock). As if it were falling off by mistake, the printer does not detect that it is hot, but continues to heat, which has led to several houses being burned. I myself have experienced that the fan on the extruder, which feeds filament, melted.

If you do not use an "all-metal extruder", the Teflon tube in the tube, already at 250 C, will emit harmful fumes.

The idea is that the IR thermometer (GY-906) is aimed at the heat block so that it measures the temperature, at the same time as the Smoke detector (MQ-2) measures any. smoke evolution. This disconnects the 230V supply before the printer's power supply with a relay, which I currently. is in doubt whether to be NO or NC.

NO: has the advantage that it increases security in that the printer cannot turn on until security is established.

NC: has the advantage of reducing fault interruptions, but since the printer does not continue after a power failure, this should not cause concern.

When it works for me, I will try to implement the security in octopi.

Preliminary shopping list:
1 pcs. Arduino Nano.
1 pcs. GY-906 IR termometer, based on MLX90614.
1 pcs. MQ-2 Smoke detector.
1 pcs. Relay, so the 230V supply is cut off automatically.

In addition, I have added 2 pcs. Heat Bed MOSFETs, I saw, limit the current that flows through the terminals on the controller board.

The manufacturers strongly recommend that you do not leave a lit 3D printer unattended, and that a smoke alarm is installed in the immediate vicinity. This project is intended as an additional help.

The code is on my GitHub profile: OZoneSQT

Here is a project / kit based on Anet A8 SAFE mod.

But modified, and laid out on a print in Arduino Nano size with connections to the individual sounders and sensor.