Z axis gets reset to zero before print starts
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I have a curious problem that appeared after changing back to a standard V6 clone from a dragon hotend. When I start a print the Z axis zero gets reset before the first movement. Then it air prints about 35mm above the bed. If I add a short pause (G4 S1) to the gcode file before the initial movement command it prints normally. I am currently using Cura 5.0 slicer with no additional starting gcode commands. Initially my start.g file was unchanged. I have tried several additions and deletions to that file without success. Including or excluding the wipe macro had no effect.
Any suggestions? Editing the gcode file every time is a pain.
The printer is a custon coreXY with a Duet3 and a single rev1 toolboard. It has 3 Z axis steppers for bed leveling. I have been running release 3.3 before and after the hotend switch. My Z probe has been a Precision Piezo Orion throughout.
echo "start.g executing"
M220 S100 ; reset speed factor
M557 X35:285 Y35:285 S50 ; define default mesh grid
G1 Z35.0 F1000 ; Move the platform down to 35mm
;G92 E0 ; reset extruder
;G1 X150 Y0 F6000
;G29 S0
;M376 H3
;G1 E5 F100 ; Extrude a short distance before wipe
M98 P"0:/macros/wipe"
;G4 S1 ; wait then beep
M300 S500 P500
G4 S1wipe macro
if !move.axes[0].homed || !move.axes[1].homed || !move.axes[2].homed
exitif move.axes[2].machinePosition < 35
G1 Z35 F500G1 X-15 Y20 F6000
while iterations < 4
M280 P4 S115
G4 S0.2
M280 P4 S80
G4 S0.2
continueM280 P4 S20
Typical starting section of the gcode file
;FLAVOR:RepRap
;TIME:1838
;Filament used: 7.81383m
;Layer height: 0.35
;MINX:103.875
;MINY:90.082
;MINZ:0.35
;MAXX:144.943
;MAXY:219.915
;MAXZ:17.85
;Generated with Cura_SteamEngine 5.0.0
T0
M190 S70
M104 S245
M109 S245
M82 ;absolute extrusion modeM83 ;relative extrusion mode
G1 F1800 E-1
;LAYER_COUNT:51
;LAYER:0
M107
M204 T1500
M566 X1200 Y1200
G4 S1
G0 F7200 X105.327 Y92.253 Z0.35
G0 X103.876 Y96.79
M204 P1000
M566 X2100 Y2100
;TYPE:SKIRT
G1 F1500 E1
G1 F1800 X103.886 Y96.111 E0.07411Reference files
config-g-6-14-22.txt
M122.txt
M122-B121.txt -
Is it homing correctly?
When exactly is the z axis getting set to 0?
@wifibeagle said in Z axis gets reset to zero before print starts:
appeared after changing back to a standard V6 clone from a dragon hotend.
@wifibeagle said in Z axis gets reset to zero before print starts:
My Z probe has been a Precision Piezo Orion throughout.
The piezo depends on the rigidity and weight of the hotend. Perhaps when changing the hotend it's characteristics changed and it's triggering early in the homing move?
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@phaedrux Thank you for your suggestions.
There is no problem homing, zeroing the Z axis, G32 bed leveling or probing to verify the bed leveling.
The reset seems to occur with the first slight XY move at the start of a print. Then a short delay, less than a second, Z zero reset and the start of the air print. It all happens so fast it is hard to tell the exact behavior. I would not expect the Z probe to be active at this time.
There is a slight sensitivity difference for the piezo after the hotend change. It seems slightly less sensitive than before. Translating between probe locations at 6000mm/min there are frequent probe triggers. I have a 0.8 second delay between motion and the start of a probe. That has eliminated false trigering. Reducing the acceleration during probing also helped but not as much as the delay.
I upgraded to 3.4.1 yesterday for other reasons. I will try a print today without adding the G4 delay and see if the problem persists.
John
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@wifibeagle
Reprinted a part that required the G4 delay after deleting that command. No problems with the print. It appears 3.4.1 may have cured the problem even if it has not completely solved the mystery.I can live with that!
