Restart 3d print or CNC job after power failure

[AndreyP]

Using KFLOP for complex 3d printer machine.
So after slicing the 3d model and executing the gcode on KFLOP any ideas on how to create a setup where if the power is shut down or some kind of glitch happens you can restart the 3d print at the last point in space on the model?

Maybe there is a way to save the last line of gcode to RAM and then on reboot KFLOP loads the last gcode line and finds it on the gcode file and then asks if you want to start from there and if so it moves to that last point and starts again. Seems to be a more complex than that solution though as I have not seen any printer/CNC that can restart after power failure.

[TomKerekes]

Hi AndreyP,

Writing to RAM probably wouldn't work as that would be normally lost with loss of power.

You would probably need to change KMotionCNC to continually write the GCode Line number to a disk file. Even then the disk file might be lost or corrupted on the loss of power. Maybe use a few files and somehow force a cache flush.

I don't know what your process is but resuming after a stop can be difficult even if you know exactly where because things might have cooled down, shrunk, curled, moved, etc.

One crude approach might be for KFLOP to monitor the Z height. It might then be able to determine the current layer number from when it sees a new maximum Z height. Then write this to a Disk file. Or maybe just measure the Z height when the system is turned back on.