Are G2/G3 arcs still broken into G1 segments?

TDK

In the documentation, there is nothing that indicates that G2/G3 commands are broken up into line segments. I know this is what has traditionally been done. Does RRF 3.x still break arcs up into segments? Still a fixed 0.2mm distance per segment?

The best I could find while searching was this ~2 year old post where dc24 said arcs are broken up into 0.2mm segments:
https://forum.duet3d.com/topic/7983/g1-vs-g2-g3-for-cnc/6

I'm trying to avoid ringing issues and wondering if converting lines to arcs and slightly rounding paths prior to printing would help at all.

bot

IIRC, they are segmented with a length that depends on the radius of the arc. It's a hardcoded relationship. I'm not aware of exactly how or where it's implemented in code.

dc42

G2 and G3 commands are still broken into line segments. However, a G2 or G3 command is much more efficient for the Duet to processes than the equivalent set of G1 commands.

TDK

@dc42 said in Are G2/G3 arcs still broken into G1 segments?:

G2 and G3 commands are still broken into line segments. However, a G2 or G3 command is much more efficient for the Duet to processes than the equivalent set of G1 commands.

Thanks for confirming. Does the user have any control over how this is done or is it a hard-coded 0.2mm per segment?

PCR

https://hackaday.com/2020/11/03/this-gcode-post-processor-squeezes-lines-into-arcs/

A Former User

@TDK
(...some time in the future with a higher processor-speed maybe and superduper high motor movements would be great to be able to break this segments down as fine as a user wants... +1 here for maybe the duet4 or so... (with current speed and resolutions I do not need it really - let´s wait till we have slicer and mainboards that support vectors first maybe?))

TDK

Very much not a new thing:
https://github.com/TheLongRunSmoke/g1tog23

I saw in other posts that the distance is not user-configurable, and is actually not fixed, but it's hard to know if that is still accurate.

Still a bit disappointed G2/G3 isn't natively supported but it is what it is. I didn't verify the fix in the latest RC.

dc42

The segment size used to approximate arcs varies according to the requested speed. The slower speeds typically used by CNC machine Gcode give rise to smaller segments.

Is the segment size chosen by RRF causing a problem on the job you are running?