Configuring "resume a print after a power failure"
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Hi, I want to configure "resume a print after a power failure" option on my Duet but I have one problem with understanding documentation. It says that I need to use G92 command in sys/resurrect-prologue.g to tell the printer Z coordinate. But what parameters should I use?
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@anraf1001 If the machine lost power the position of the motors is no longer known so usually you need to home the printer again in
sys/resurrect-prologue.g
. On many printer types homing X and Y is not a problem even if a partial print is already in the build-plate but homing Z can be problematic as some part of the printer could collide with the partial print.There are several ways around this problem
- Your printer has layout that makes regular homing possible even with a partial print of arbitrary size on your build plate
-> just putG28
in yoursys/resurrect-prologue.g
and you're done - You have a way of reliably determining the Z position of your printer
-> useG28 XY
to only home X and Y andG92 Znnn
wherennn
is the current position of Z to tell the printer the current Z height without the need of the homing process for Z
- Your printer has layout that makes regular homing possible even with a partial print of arbitrary size on your build plate
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@wilriker In second scenario you need to update the position every time you use power-recovery?
Not really user friendly. -
@wilriker said in Configuring "resume a print after a power failure":
- You have a way of reliably determining the Z position of your printer
-> useG28 XY
to only home X and Y andG92 Znnn
wherennn
is the current position of Z to tell the printer the current Z height without the need of the homing process for Z
Yup But I asked what parameters should I use. I need to know what Z coordinate was beore power loss.
- You have a way of reliably determining the Z position of your printer
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@anraf1001 This is basically under discussion in this thread. Look at my (currently) last post in this thread, there I explain where you can find this information.
@dragonn Yes, you are right, this is currently a rather tedious and manual process in case you cannot home your printer with something on the build plate. I am in the lucky position that by coincidence I can home my printer in Z if Y is at max unless that print would basically cover the whole build plate (it probably never will). So in my case I have
G28 XY ; Home X and Y regularly G0 Y216 ; Move Y to the front maximum G28 Z ; Home Z now where the head has least chance to hit something
in my
resurrect-prologue.g
. But as I said, I am lucky here. -
Another option is to add a Z-max homing switch to use for homing Z only after power recovery.
I could add a G92 command in resurrect.g to set the head coordinates to the location at which power failure occurred. This won't take account of any Z-raise that your your power fail script attempts to do.
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@dc42 said in Configuring "resume a print after a power failure":
I could add a G92 command in resurrect.g to set the head coordinates to the location at which power failure occurred. This won't take account of any Z-raise that your your power fail script attempts to do.
I have a feeling that this should then be configurable or happen before
resurrect-prologue.g
is called so that the user has means to override/prevent this. Other than that I like the idea. -
@wilriker said in Configuring "resume a print after a power failure":
@dc42 said in Configuring "resume a print after a power failure":
I could add a G92 command in resurrect.g to set the head coordinates to the location at which power failure occurred. This won't take account of any Z-raise that your your power fail script attempts to do.
I have a feeling that this should then be configurable or happen before
resurrect-prologue.g
is called so that the user has means to override/prevent this. Other than that I like the idea.I'll write that command immediately before the call to resurrect-prologue.g.
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hi
is it possible to use an break on Z ?
so with power or start print, the break ist open (magnet ?/Solenoid)
and when power fail, duet activates the break (magnet off) and saves the position ? -
@knaudler if your brake can be triggered by the duet you could modify the commands to run on power loss to trigger it.