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02-08-2016, 02:35 PM #1
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- Oct 2014
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Marlin end code - relative distance
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
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02-15-2016, 11:39 AM #2
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- Nov 2014
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- New Orleans
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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.Last edited by dustmann; 02-15-2016 at 03:09 PM.
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02-15-2016, 12:41 PM #3
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- Burnley, UK
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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.
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02-15-2016, 12:56 PM #4
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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.
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02-15-2016, 01:29 PM #5
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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)
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02-15-2016, 03:10 PM #6
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- New Orleans
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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.
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02-15-2016, 03:23 PM #7
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- Oct 2014
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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.
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