[feature or bug][3.5.0-rc.3] G10 retract z-hop ignores homing

timschneider

G10 with z-hop configured ignores homing state of z-axis.

M207 S1.50 R0 F2000 T2000 Z3.5      ; retraction

Tested on:

FIRMWARE_NAME: RepRapFirmware for Duet 3 MB6HC FIRMWARE_VERSION: 3.5.0-rc.3+ ELECTRONICS: Duet 3 MB6HC v1.02 or later FIRMWARE_DATE: 2024-02-04 11:40:04

in SBC Mode.

Is it a feature or a bug?

Tim

dc42

@timschneider is this a problem, if it still hops by the configured amount? Or have you found that it doesn't?

timschneider

@dc42 oh yes, it is a problem, I was probing around with an unhomed printer and tried to reproduce an error I had in the last print where I was unable to acknowledge a blocking messages while printing. So I started a jobfile with no movements and only a G4 init to put the printer into paused state. The printbed was at its max and unhomed, when I cancled the print, the printer tried to move the printbed further in the max position with a strong sound. So I started to investigate and put a
if move.axes[2].homed infront of every z movemend command - but the problem was still there until I stumbled over the G10. after putting a if move.axes[2].homed infront of the G10, the problem was gone.
I was not sure if it is a feature or bug, but at least it is some sort of inconsistency, as the tool/extruder is not driven when it is not heated up with G10, even if it tries to.

timschneider

@dc42
ok, my use pattern was the cause of the "problem"

The problem occures when you do the following:

printer is unhomed

T0 active and Z-Hop configured

M207 S0.45 R0 F2000 T2000 Z0.5       ; retract for PLA

content of cancel.g

G10
M99

content of pause.g

M99

content of jobfile.g

T0
G4 S10

start jobfile.g
pause printjob via DWC (M24)
cancel printjob via DWC (M0)
repeat the above steps and the z-axis will accumulate the z-hops, 0.0, 0.5, 1.0, 1.5 ... and so on

it looks like, cancel is resetting the retration state without undoing the retraction/z-hop if it was retracted and is adding the z-hop to the current z-axis position.

M115

FIRMWARE_NAME: RepRapFirmware for Duet 2 WiFi/Ethernet FIRMWARE_VERSION: 3.5.0-rc.3 ELECTRONICS: Duet WiFi 1.02 or later + DueX5v0.11 FIRMWARE_DATE: 2024-01-24 17:56:24

//Edit
there is no difference if the printer is homed or not - G10 and cancel will ignore machine limits.

ok this would explaine another usecase we often use.
If we have very long printjobs > 1 week, we sometimes use M916 to change the gcode mid print.

pause print
cancel print
change jobfile
edit resurrect.g
M916

and sometimes the z-position does not match the current machine position from the printhead (the printhead is a few mm above the printed object)

dc42

@timschneider thanks. Please file an issue at https://github.com/Duet3D/RepRapFirmware/issues.

I think a related issue is that there will be a problem if the current machine Z height plus the Z hop amount exceeds the Z maximum defined in M208. You could mention this in your issue report too.