G1 H1 Z-255 doesn't seem to work

jov

The homing of the Z axis with the command G1 H1 Z-255 F360 doesn't seem to work. This is my homeall.g:

; generated by RepRapFirmware Configuration Tool v2.1.8 on Mon Feb 17 2020 21:33:03 GMT+0100 (Central European Standard Time)
G91                     ; relative positioning
G1 H2 Z5 F6000          ; lift Z relative to current position
G1 H1 X-290 Y-305 F1800 ; move quickly to X or Y endstop and stop there (first pass)
G1 H1 X-290             ; home X axis
G1 H1 Y-305             ; home Y axis
G1 X5 Y5 F6000          ; go back a few mm
G1 H1 X-290 F360        ; move slowly to X axis endstop once more (second pass)
G1 H1 Y-305             ; then move slowly to Y axis endstop
G1 H1 Z-255 F360        ; move Z down stopping at the endstop
G90                     ; absolute positioning
G92 Z0                  ; set Z position to axis minimum (you may want to adjust this)

Every other command in the homeall.g works if I enter them in the console window, except that one. If I replace the last three lines with:

G30
G90
G92 Z5

I get the proper homing behaviour.

But I don't understand why G1 H1 Z-255 doesn't work, am I missing something here?

SIam

~~your z-min is on 0 so you can't drive in to negative area~~

G92 Z0

~~btw why you have so big negative settings?~~

i have overseen that you use the relative positioning...

Phaedrux

Are you using a probe or an endstop switch?

G30 is for the probe, so if that works, you must be using a probe.

G1 H1 Z-255 will only work if you have an endstop configured and installed for Zmin.

jov

@Phaedrux said in G1 H1 Z-255 doesn't seem to work:

G1 H1 Z-255 will only work if you have an endstop configured and installed for Zmin.

Aaaaaah, thanks. I'm using a probe indeed (Piezo Orion).

Danal

H2 will work with a probe. Maybe.