On 8/13/25 09:03, Steffen Möller via Emc-developers wrote:
Gesendet: Mittwoch, 13. August 2025 um 14:06
Von: "andy pugh" <bodge...@gmail.com>
An: "EMC developers" <emc-developers@lists.sourceforge.net>
CC: "Steffen Möller" <steffen_moel...@gmx.de>
Betreff: Re: [Emc-developers] Building closer community FreeCAD & LinuxCNC
On Wed, 13 Aug 2025 at 12:50, Steffen Möller via Emc-developers
<emc-developers@lists.sourceforge.net> wrote:
* G-code compatibility - what can we do to ensure that anything that FreeCAD
generates can indeed be interpreted by LinuxCNC in an automated fashion?
LinuxCNC supports splines and NURBS. As far as I know no CAM software
outputs those.
In fact, many CAM softwares don't even output arcs....
https://linuxcnc.org/docs/stable/html/gcode/g-code.html#gcode:g5
I am not at all clear if there is any technical advantage in
outputting splines / NURBS from a CAM other than smaller file sizes in
some cases, but that's not really of much value as most CAM G-code is
never read by human eyes and the file size is small in real terms.
I like it. So we would have a best-possible semantic equivalence of
what is modelled with what is described in G-code.
I recall some issue of FreeCAD-LinuxCNC compatibility that you, Andy, fixed.
Found it:
https://github.com/LinuxCNC/linuxcnc/issues/1528
I thought it would be nice to catch such issues somehow automagically,
maybe with a couple of parts modeled in FreeCAD with various sorts of
corners, edges, shapes and forms that we could then somehow run and compare
as part of our CI testing.
Wow, the I word in that example was 5 million user units! I
can imagine that small differences could fall off the
insignificant bits of the floating point value, at least if
not done in double precision. It seems that an arc was not
reasonable with such a huge radius, it would be
indistinguishable from a straight line.
Jon
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