Printable View
I am trying to set my end GCODE to raise the Z axis 25mm above the top of the print.
Right now I am using G1 Z25 F5000 ; lift nozzle but if my print is higher than 25 the
head crashes into the print.
Will this fix that -
G91 ; set relative positioning
G1 Z25 F5000 ; lift nozzle
Which slicing software are you using? slic3r sets a G90 command at the beginning of a print to use absolute coordinates. Your G91 command set at the end of the G-code can remedy this as you have noted.
edit:
I have noticed that after completing a print and homing X/Y, it appears that when a new print begins without resetting the printer, the motors try to home even further (from the home position) resulting in a lot of skipped steps or mechanical crashes. Therefore as Mjolinor mentions below this is definitely not the recommended solution.
It will work but the potential problem is that with relative distances and only a Z switch you may not have room to raise 25mm.
These are the sort of problem that are caused by using only a subset of proper Gcode. In real Gcode you can do conditional things and make more complex decisions.
I pay attention to the height of the printed object and if that would put me too high to raise 25mm I just set it to raise 2-3mm. Most of my prints are not that high, so I am good...for now.
Does this break the parameters of the limits set in firmware? When I add a G91 followed by a G1 Z25 on a 10mm test cube, the LCD is reporting 35.0mm as the final Z position before homing. A G92 command without parameters would set all axes to 0, which could cause mechanical issues (loss of current position relative to endstops)Quote:
Originally Posted by Mjolinor
I have had quite a few mechanical crashes after adding this end code, it works fine for the first print, but causes crashes at the beginning of a new print. See my original post above.
I'm using Simplify3D. It issues a G90 at the beginning as well.
I have not seen any change in my homing and auto bed leveling behavior since implementing this.