FreeCAD Gcode not working in Linuxcnc

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22 Jan 2022 22:24 #232838 by strahlensauger
I constructed a gnome  door for the kids in FreeCAD and as I put it on my mill, Linuxcnc only showed huge circles instead of the door.
I inspected the gcode and found large I and J Parameters, which LCNC probably interprets wrong. If I delete code from line 150 onward and keep the last thee lines the code behaves as expected.
This occurs on my real machine as also on simulation.
Any ideas?
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23 Jan 2022 09:24 #232868 by cmorley
I don't see G64 setting - that can make corners _very_ rounded.

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23 Jan 2022 14:30 #232877 by strahlensauger
Thank you for answering, I'll check that.
Opening the code in ncviewer.com/ shows the correct lines,
just Linuxcnc shows great circles.
This happens on a test RPI running LCNC as well as on my mill as well as on a simulation under Linuxcnc.
I wonder if I am the only one experiencing such strange behaviour, the drawing just consists of straight lines...
Changing Gcode G90 to G91 shows me at least the drawing inbetween huge circles in LCNC.
If I move the corner points in FreeCAD sometimes the circles disappear (probably when the i and j Parameters get small) but I can not detect any systematical sheme in that...

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23 Jan 2022 23:33 #232907 by Grotius
Hi,

At my place the gcode looks like :
user-images.githubusercontent.com/448801...3f0-4f5c9bea11d2.mp4

Is this looking ok for you?

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24 Jan 2022 00:41 #232908 by phillc54
It seems that it may be doing something funky with huge I & J parameters.

Changing the G2/G3 lines with the huge I & J parameters to a G1 move appears ok.
 


 
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24 Jan 2022 00:48 #232910 by joekline9
It may be the wrong arc center mode.

G90.1 ( abs arc centers)
or
G91.1 ( incremental arc centers)

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24 Jan 2022 01:09 - 24 Jan 2022 01:27 #232912 by strahlensauger
Thank you for your engagement. That is exactly what I drew in Freecad, lcnc draws huge circles.
I just wonder why the postprocessor from freecad for Lcnc don't match.

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Last edit: 24 Jan 2022 01:27 by strahlensauger.

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24 Jan 2022 01:15 #232915 by phillc54
Yes, It does seem that LinuxCNC is interpreting it incorrectly.

If you zoom in a long way where the circles intersect on the left side then you can see the rest of the plot.

It may be best to raise a new issue on Github.
github.com/LinuxCNC/linuxcnc/issues
The following user(s) said Thank You: strahlensauger

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24 Jan 2022 15:12 #232973 by strahlensauger
I opened an issue on Github, thank you for the link.
@ phillc54: just curious; how did you edit that file to change the lines with the big numbers,
did you do all by hand or did you write a macro in vim or did you use Excel or libreoffice?

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24 Jan 2022 22:23 #233020 by phillc54
By hand, it is easy to find the required line by selecting it in the preview.

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