Generally speaking, usually R breaks at 180° where IJK can do a full 360° arc with a single command. I think it's possible to go >180 with a negative R, but I'm not sure where that ends. I've never been a fan of R because it tends to break tangency where ijk are a little more strict.
Phil T. The Feral Engineer Check out my LinuxCNC tutorials, machine builds and other antics at www.youtube.com/c/theferalengineer Help support my channel efforts and coffee addiction: www.patreon.com/theferalengineer On Fri, Feb 25, 2022, 10:38 PM cogoman via Emc-users < [email protected]> wrote: > I believe that R arcs that are 90 degrees or less are going to come out > very close to the IJK versions, but if you want a full circle, it's > better to break it up into 4 90 degree arcs. I don't know just where > radius arcs start to diverge from IJK arcs, but I would guess that 180 > and 360 degrees are problem spots. > > On 2/10/22 16:30, Les Newell wrote: > > That code is testing the 180 degree issue, which is not usually a > > major problem as far as accuracy is concerned. Try using a R value of > > 5.002, instead of 5.0025. In this case the arc does not technically > > fit. Some controllers throw a fit and some quietly fudge the radius to > > fit. I think LCNC fudges the radius, adding a tiny amount of error but > > it won't be enough to measure. > > > > Try using an R arc that's really close to a circle. Tiny rounding > > errors in the X,Y coordinates can move the arc all over the place. > > > > Les > > > > On 10/02/2022 00:17, andy pugh wrote: > >> Thde docs state that a 7% difference was seen, but with some brief > >> experimentation I can't see it: > >> > >> F1000 > >> G0 X0 Y0 > >> G2 X10 Y0.1 R5.00025 > >> G0 X0 Y0 > >> G2 X10 Y0.1 I5.0 J0.05 > >> M2 > >> > > > > > > > > _______________________________________________ > > Emc-users mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
