Plan C | DIY WIRELESS 3D PRINTER SAFETY SHUTDOWN SYSTEM @Plan-C | Uploaded November 2017 | Updated October 2024, 1 hour ago.
drive.google.com/open?id=1nXcDwCVmPUcDuk1CiX6P3krTGfCGPx34
I cobbled together a few ideas from the internet and came up with this. It is a wireless, stand-alone monitor which will shut off mains power to a 3d printer using an Arduino and a (hacked) commonly available radio controlled socket from Maplins.
The Arduino will monitor for smoke or over-temperature on two thermistors. The thermistors in the example are placed on the hot end and bed but could be anywhere. A moving-average temperature (to smooth readings) is taken for each via a Steinhart-Hart equation is and compared to a set, user-defined limit for each. If a limit is breached or smoke is detected then a code is sent to the handset and transmitted to the socket wirelessly to turn off power. A buzzer is activated to alert the user. The whole thing runs off the 5v Arduino power, including the handset so can be powered by USB.
A draft Eagle schematic and a png picture of it are in the link. The pinout is:
D7 = Buzzer
D4 = MQ2
A0 = Bed NTC thermistor (4k7 pull-down resistor)
A1 = Hotend NTC thermistor (4k7 pull-down resistor)
Wireless - D11 (via 150 ohm resistor) to remote control signal
or
Relay version, D12 is trigger with 2k2 pull-down resistor to stop any relay 'flutter' on power-up. Do not use D13 for relay for this reason.
The wireless socket cost £6 and the Arduino Nano cost about £1.50. The MQ2 sensor was about £2 and the NTC thermistors about £1.
I have attached working sketches for two versions of the firmware and have tested both in the video. Please improve and share. The first is a wireless version and the second is for a conventional relay. I prefer the wireless approach. I had problems with my relay (cheap, faulty ebay job) and the wireless approach has less exposed wires to mess around with.
There are links in the config.h and below to the mkme youtube channel where I first saw the nano/relay idea, the rc-switch library which allows for control of wireless sockets via Arduino and a calculator for calibrating your own thermistor should you wish. I have tried my best to comment the code to make it easy to follow but I am no programmer lol. It can surely be made much better.
At the moment, the project is still on a breadboard but I will try and sketch up an Eagle board for it soon.
THIS IS AN EXPERIMENTAL PROJECT AND SHOULD NOT BE RELIED ON FOR PRINTING UNATTENDED. IT IS MERELY TRYING TO ADD ANOTHER LAYER OF PROTECTION IF, FOR EXAMPLE, A MOSFET SHOULD FAIL IN THE 'ON' POSITION AND THE ON-BOARD CPU WAS UNABLE TO SHUT OFF POWER TO THE HOT END OR BED.
I WOULD ALSO RECOMMEND FUSING THE HEATED BED AND HOT END SEPARATELY WITH AUTOMOTIVE FUSES, MAKING SURE THE BED IS PROPERLY ISOLATED FROM SPRINGS ETC WITH PLASTIC WASHERS, THAT ALL HIGH CURRENT WIRES ARE SECURELY CONNECTED AND THAT THE HOT END THERMISTOR IS SECURE.
The inspiration for this project came from the following places:
Basic Relay Idea
youtube.com/watch?v=LBr6AROebYA
Basic Socket Idea
youtube.com/watch?v=P-1EX5GqZd4
Hack Remote Idea and Code:
sui77.wordpress.com/2011/04/12/163
github.com/sui77/rc-switch
Thermistor Calibration Calculator:
thinksrs.com/downloads/programs/Therm%20Calc/NTCCalibrator/NTCcalculator.htm
Arduino IDE:
arduino.cc/en/Main/Software
Good luck All.
drive.google.com/open?id=1nXcDwCVmPUcDuk1CiX6P3krTGfCGPx34
I cobbled together a few ideas from the internet and came up with this. It is a wireless, stand-alone monitor which will shut off mains power to a 3d printer using an Arduino and a (hacked) commonly available radio controlled socket from Maplins.
The Arduino will monitor for smoke or over-temperature on two thermistors. The thermistors in the example are placed on the hot end and bed but could be anywhere. A moving-average temperature (to smooth readings) is taken for each via a Steinhart-Hart equation is and compared to a set, user-defined limit for each. If a limit is breached or smoke is detected then a code is sent to the handset and transmitted to the socket wirelessly to turn off power. A buzzer is activated to alert the user. The whole thing runs off the 5v Arduino power, including the handset so can be powered by USB.
A draft Eagle schematic and a png picture of it are in the link. The pinout is:
D7 = Buzzer
D4 = MQ2
A0 = Bed NTC thermistor (4k7 pull-down resistor)
A1 = Hotend NTC thermistor (4k7 pull-down resistor)
Wireless - D11 (via 150 ohm resistor) to remote control signal
or
Relay version, D12 is trigger with 2k2 pull-down resistor to stop any relay 'flutter' on power-up. Do not use D13 for relay for this reason.
The wireless socket cost £6 and the Arduino Nano cost about £1.50. The MQ2 sensor was about £2 and the NTC thermistors about £1.
I have attached working sketches for two versions of the firmware and have tested both in the video. Please improve and share. The first is a wireless version and the second is for a conventional relay. I prefer the wireless approach. I had problems with my relay (cheap, faulty ebay job) and the wireless approach has less exposed wires to mess around with.
There are links in the config.h and below to the mkme youtube channel where I first saw the nano/relay idea, the rc-switch library which allows for control of wireless sockets via Arduino and a calculator for calibrating your own thermistor should you wish. I have tried my best to comment the code to make it easy to follow but I am no programmer lol. It can surely be made much better.
At the moment, the project is still on a breadboard but I will try and sketch up an Eagle board for it soon.
THIS IS AN EXPERIMENTAL PROJECT AND SHOULD NOT BE RELIED ON FOR PRINTING UNATTENDED. IT IS MERELY TRYING TO ADD ANOTHER LAYER OF PROTECTION IF, FOR EXAMPLE, A MOSFET SHOULD FAIL IN THE 'ON' POSITION AND THE ON-BOARD CPU WAS UNABLE TO SHUT OFF POWER TO THE HOT END OR BED.
I WOULD ALSO RECOMMEND FUSING THE HEATED BED AND HOT END SEPARATELY WITH AUTOMOTIVE FUSES, MAKING SURE THE BED IS PROPERLY ISOLATED FROM SPRINGS ETC WITH PLASTIC WASHERS, THAT ALL HIGH CURRENT WIRES ARE SECURELY CONNECTED AND THAT THE HOT END THERMISTOR IS SECURE.
The inspiration for this project came from the following places:
Basic Relay Idea
youtube.com/watch?v=LBr6AROebYA
Basic Socket Idea
youtube.com/watch?v=P-1EX5GqZd4
Hack Remote Idea and Code:
sui77.wordpress.com/2011/04/12/163
github.com/sui77/rc-switch
Thermistor Calibration Calculator:
thinksrs.com/downloads/programs/Therm%20Calc/NTCCalibrator/NTCcalculator.htm
Arduino IDE:
arduino.cc/en/Main/Software
Good luck All.
