Suicide Switch by Vl4d

Last crawled date: 2 years, 12 months ago

Disclaimer: I am not responsible for anything you do.
The problem:
Many a time I have needed to run a print well into the night, leaving me with two options. Leave the printer running all night or wake up at some ungodly hour to turn it off.
The solution:
Enable to printer to pull the plug on itself at the end of the print, in a reliable, simple to implement solution.
My printer started life as a Da Vinci 1.0, however it's now running an mks gen 1.4 board which has servo outputs. Your printer may differ.
For this, you will need:
A control board that has a servo output.
1 x R/C Relay such as https://littlebirdelectronics.com.au/products/pololu-rc-switch-with-relay-assembled
1 x r/c servo extension cable
1 x regular relay such as https://littlebirdelectronics.com.au/products/30a-horn-relay-spst
1 x momentary push button of your choice (hence forth known as the ignition button)
Please refer to the diagram how to wire this, if it doesn't make sense then you probably shouldn't be messing with your printer.
How it should work.

Power switch off, press ignition - it will power on, but then die when you release the ignition button, no bueno.

Power switch on, press ignition - it will power on, energize the main relay and keep it on even after you release the ignition button.
To kill it either:

Power switch off - duh...

Insert m280 p1 s2000 in your end gcode.
(where p is the number of your servo -1, eg 0 is servo 1, 1 is servo 2 etc) I had a Z-probe on p0, hence why this is p1. This will switch the rc servo, which will interrupt the circuit keeping the main relay closed, which in turn will interrupt the circuit keeping the power supply on.
It's like the worlds most boring game of domino's.
Possible issue:

The mks gen 1.4 board 'maintains consciousness' if connected by usb even if the main power is out. It's a good idea to call m280 p1 s0 after the kill command to ensure rc servo/relay/thing releases. Otherwise if your printing off a sd card with no usb connected, everything should reset once power cuts out.

For some reason, sometimes my m280 p1 s2000 is ignored, I found if you call m280 p1 s0 before hand this should't be an issue.
To be safe, put this in your end gcode.
m280 p1 s0 - rc relay closed, which should be default option
m280 p1 s2000 - rc relay open, kill everything
m300 - beep just to buy some time and make sure everything is thoroughly killed.
m280 p1 s0 - reset rc relay in case usb power is present. (printer will stay dead until you press the ignition button).
BTW you may need to make a couple easy changes in your firmware (I'm using marlin) if you haven't already enabled the servos.
P's,
The screw posts for the r/c relay servo broke when I tried to screw it in, ended up just using double sided tape instead.
Big servo uses a m3 screw, rc servo 2mm self taping screws I had lying around.