$12=0.002 grbl arc setting question

hi carvers

this GRBL arc setting is extremely fine, do i really need it that fine? and would i possibly be better with a courser setting , ie, $12=0.01 or $12=0.05 ?

my thinking is, it would send less lines through grbl and maybe improve performance ?

what say you ?


sorry about the election

Depending on how your g-code generating software handles arcs (some high level programs break the arc up and send linear segments to grbl = high g-code rate to grbl) and some use G2 and/or G3 (one g-code line per arc).

If the upper level code uses G2 and/or G3 then grbl will break the arc movement up into linear segments using the $12 setting.

Here is a comment from the source code for grbl handling the arcs (settings.arc_tolerance = $12).

The chordal tolerance of each segment is configured in settings.arc_tolerance, which is defined to be the maximum normal distance from segment to the circle when the end points both lie on the circle.

The $12 setting allows the user to select how close the linear segments approximate the path of the arc.

I have not done any testing to see the effects of changing $12.

If no one else answers with direct experience, try some small changes to see what the effect is and fine tune what is acceptable for you.

[Edit] - Well, this question caused me to wonder what the effect would be, so I did a little testing with my pen attachment to the spindle mount. Much as I expected, but this will give you an idea of what amount of change really affects the quality of the arc (this is using G2/G3). Pen marks a 1mm line.


Smiley Faces :slight_smile: awesome use of technology LOL ! (lean on ladder) ? bhahaha,

i had another thought, im trying to work out what the steppers are capable of then matching that .

maybe i should shutup and carve something !!!??? LOL! (lurch on liquor)?

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Looks more like a frog to me.

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