Sometimes Z moves in Wrong Direction

I have enabled Z axis Reverse Z and Relative Z moves
I have also included a start up GCode that homes, turns on inline mode and sets Z to the desired height:
G1 Z140 F2000
M3 I S0

After getting an operation set - MOST of the time the system runs properly.
My machine Homes Z by raising all way up (and hits limit sw). The homed Z position in Marlin is then 210mm. That’s why I set Z Reverse Direction. So, when i start a run I need to move Z down to the desired height above the material (say to Z 140) . HOWEVER, sometimes, without changing the Z Revers Direction or any other Z setting, when i hit the > PLAY/START button, after homing it tries to move the Z axis UP instead of Down to the desired Z height. Since the Z axis is already at the top, the stepper motor stalls and hammers away.
This seems to happen “Sometimes” after I open and close the Device settings, even if I don’t make any changes at all in the settings.
When I use the MOVE commands to manually move the Z axis, it goes in the right direction.
To get it back working properly, well, I never figured out what really corrects it, because each time i try and number of things, and finally it will start working right again. Things I’ve tried were to move it from the Move window, or opening and closing the device settings, or? or just closing the program and reopening. When it is not moving in the right direction I save the GCode file and the file has the correct Gcode. I can close Lightburn and run the Gcode using Repetier Host and it works properly.

ANOTHER Bizarre behavior is Changes to the GCode don’t take effect right away, or revert back to previous setting. When I use different thickness material, I need to change the Z height in the startup Gcode, say i had it set to G1 Z136 F2000 and I edit it to G1 Z140 F2000
When I run the program, it moves Z to 136 mm, the Previous setting. I go back in to Device settings and check the Gcode and it shows 140, run it again, and it uses the previous 136 value. I close Lightburn and restart it, go to the settings and now the GCode shows Z136 (the previous value) so somehow the program never really changed the value all the way through its internal code. I then again edit it to Z140 and then it used the new value. Really strange.

This topic was automatically closed 30 days after the last reply. New replies are no longer allowed.