One-press resume printing after power failure

dc42

I think the long-term solution will come when we support variables and parameters in GCode commands. Then we will be able to pass the Z height at which the print stopped to resurrect-prologue.g, and it can be used in a G92 command in that file.

dc42

Firmware 2.01 beta 2 puts a G92 command in resurrect.g, just before it calls resurrect-prologue.g.

resam

This is a step in the right direction!

As you clearly stated, this does not account for any Z movement in the command string when the print is stopped with M911.

Thinking about it some more, this means that people who can't home Z with a print on the bed should NOT perform any Z movement in the command string when the print is stopped with M911, because the G92 will not account for it, and you will end up 3mm too low (inside you print).

Since this would leave a hot hotend directly over your print, causing it to warp/melt, adding a Z-hop would still be beneficial.

@dc42 how about adding a new parameter to M911 that controls when and which G92 commands to insert. Something like:
M911 S19.8 R22.0 T0:0:2 P"M913 X0 Y0 G91 M83 G1 Z3 E-5 F1000"

With Tx:y:z being a single digit for each axis:

0: do not use G92 for this axis (there must be a G28 in resurrect-prologue.g for this axis!)
1: run G92for this axis with the last saved position before calling resurrect-prologue.g
2: run G92for this axis with the last saved position after calling resurrect-prologue.g

For my CoreXY machine, I would use T0:0:2, because I can home X and Y in the resurrect-prologue.g, but afterwards, I want to use G92 to set my Z height.
This allows people to not home at all, as well as doing a "partial" home for some axis.
Maybe this also helps people with absolute extruder coordinates, I'm not sure how this is currently handled?

Does this make sense, or am I missing anything?

wilriker

@resam I think you have a small mistake in your description of what "2" means because it is identical to what "1" means. I guess that 2 would mean setting G92 after resurrect-prologue.g, wouldn't it?

resam

@wilriker thanks - copy-paste error

dc42

@resam said in One-press resume printing after power failure:

This is a step in the right direction!

As you clearly stated, this does not account for any Z movement in the command string when the print is stopped with M911.

Thinking about it some more, this means that people who can't home Z with a print on the bed should NOT perform any Z movement in the command string when the print is stopped with M911, because the G92 will not account for it, and you will end up 3mm too low (inside you print).

Since this would leave a hot hotend directly over your print, causing it to warp/melt, adding a Z-hop would still be beneficial.

@dc42 how about adding a new parameter to M911 that controls when and which G92 commands to insert. Something like:
M911 S19.8 R22.0 T0:0:2 P"M913 X0 Y0 G91 M83 G1 Z3 E-5 F1000"

With Tx:y:z being a single digit for each axis:

0: do not use G92 for this axis (there must be a G28 in resurrect-prologue.g for this axis!)

1: run G92for this axis with the last saved position before calling resurrect-prologue.g

2: run G92for this axis with the last saved position after calling resurrect-prologue.g

For my CoreXY machine, I would use T0:0:2, because I can home X and Y in the resurrect-prologue.g, but afterwards, I want to use G92 to set my Z height.
This allows people to not home at all, as well as doing a "partial" home for some axis.
Maybe this also helps people with absolute extruder coordinates, I'm not sure how this is currently handled?

Does this make sense, or am I missing anything?

There is no guarantee that the Z hop in your power fail script will be completed, because the power reserve might run out first.

resam

@dc42 said in One-press resume printing after power failure:

There is no guarantee that the Z hop in your power fail script will be completed, because the power reserve might run out first.

Yes - I'm fully aware of that. But I feel like taking a risk today