Unwanted Z move after "Pause at Height"

[guyzly 1]

Can someone see why I get this Z movement after Pause?  I have done this a few times with success but am unable to find what is causing the Z axis to move down to the bed and then the Head collides with the print.

;TYPE:CUSTOM
;added code by post processing
;script: PauseAtHeight.py
;current layer: 107
M83 ; switch to relative E values for any needed retraction
G1 F1500 E-1
G1 F300 Z22.6 ; move up a millimeter to get out of the way
G1 F9000 X222 Y222
M104 S200 ; standby temperature
M117 2
M18 S1800 ; Set the disarm timeout
M0 ; Do the actual pause
G28 Y
M109 S210 ; resume temperature
G1 F1500 E1
G1 F199.998 E1; Extra extrude after the unpause
G1 F1500 E-1
G1 F9000 X145.046 Y144.755
G1 F300 Z21.6 ; move back down to resume height
G1 F1500 E1
G1 F2139.4 ; restore extrusion feedrate
M82 ; switch back to absolute E values
G92 E704.4168
;LAYER:107
;TYPE:WALL-INNER
;MESH:Cage3B.stl
G3 X144.459 Y145.013 I-0.764 J-0.943 E704.43832 F1069
G1 X143.691 Y145.016 E704.46386
 

[Dustin 193]

I'm only seeing 2 z moves.. these appear to be correct distances..
if there is more than this going on, the issue is firmware side.

[guyzly 1]

Thanx,

I had the G28 Y code in there because I had not learned to put the delay for stepper motors to turn off.  I was doing the "place item (magnet) in print" and the Y axis slide during the process so rehoming the Y axis fixed that.  Don't know why but when I cut the G28 Y out, the problem went away.  Oddly, I have done several successful prints with rehoming the Y but in the end putting a delay in stepper motor deactivation was the real fix.

Just starting with the Gcode thing so I appreciate the feedback.

[GregValiant 1,491]

This is just an FYI...

Depending on the "repeatability" of the end stop switches - it is generally not a good idea to home any axis during a print.  The switches are going to vary at least a little bit every time you ask for homing.  The "0" position this time will likely not be exactly the same as the "0" position last time.

When the X and/or Y are involved during a print you can get a minor but noticeable layer shift.  When it happens with the Z you can get an over-extruded layer (the new Z0 is a bit too low), or an under-extruded layer (the new Z0 is a bit too high).

[guyzly 1]

Agreed. Thx Greg