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gcode that is generated question...

Posted by ampapa 
gcode that is generated question...
December 10, 2017 02:47PM
I'm running a CoreXY machine and generated some code today with slic3r and noticed when reviewing the file that the "lift nozzle" setting would move my Zaxis in the opposite direction to lift the nozzle. Is there a setting in the software to accommodate for this or do I need to manually make this change somewhere?

Are there other settings as well that need to be addressed for the machine?
; generated by Slic3r 1.2.9 on 2017-12-10 at 17:41:26

; external perimeters extrusion width = 0.40mm
; perimeters extrusion width = 0.48mm
; infill extrusion width = 0.48mm
; solid infill extrusion width = 0.48mm
; top infill extrusion width = 0.48mm

M107
M190 S60 ; set bed temperature
M104 S195 ; set temperature
G28 ; home all axes
G1 Z5 F5000 ; lift nozzle

M109 S195 ; wait for temperature to be reached
G21 ; set units to millimeters
G90 ; use absolute coordinates
M82 ; use absolute distances for extrusion
G92 E0
...

Thanks for you help.

ampapa,
Re: gcode that is generated question...
December 10, 2017 07:43PM
That line separates the nozzle and the bed by 5mm so the nozzle doesn't hit or scrape the bed on subsequent moves. The comment assumes it's the nozzle moving but in actuality it doesn't matter. As long as your Z coordinates correspond to how far away the nozzle is from the bed it's fine. The comment (which starts at the semicolon and ends at the line break) is ignored by the printer, so you can leave it or change it, or, if your configuration doesn't require that move to safely move to the coordinate where extrusion will begin, you can remove the line entirely.
Re: gcode that is generated question...
December 11, 2017 03:52AM
Quote
IMBoring25
As long as your Z coordinates correspond to how far away the nozzle is from the bed it's fine.

Sorry maybe I didn't ask the question correctly.

Since the Gcode produced is running a G28-home all zeroing the Z axis, if I then were to manually enter the Gcode produced into my control panel, I'm using a Duet, my nozzle will move 5mm closer to the print bed and effectively run it into the bed unless I'm missing something here.
G1 Z5 F5000

To lift the nozzel in my case it would need to run
G1 Z-5 F5000
which I'm not sure would do anything since the Z axis has been zeroed and there would be no additional movement it can make to offset the bed.

Thanks,
Re: gcode that is generated question...
December 11, 2017 06:17AM
I wondered if that was what you meant. When you're configuring axis directions, you should always look at how the nozzle is moving relative to the print surface, regardless of which of the two is doing the movement. If positive Z movements move your nozzle and bed closer together, you need to either change Z axis direction in the firmware or reverse the wiring on the bed steppers, then make sure the endstop and homing configuration in the firmware works with whichever you've done.

This line is only the beginning of your problems if you've set up your build volume in Z-negative space. I don't think there's any slicer out there that can be configured to pass increasingly negative Z coordinates as the part builds up.

Edited 1 time(s). Last edit at 12/11/2017 06:19AM by IMBoring25.
Re: gcode that is generated question...
December 11, 2017 07:04AM
Thanks for the explanation.

I'm continually thinking of the print head moving and not the Z axis actually doing the movement.. so in that case Z+ would be correct for increasing the distance between the print head and the bed.thumbs up

Problem solved... well actually no problem to begin with.

Ampapa,
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