Machine not executing G02 instruction

Hi all;

Below is the first few lines of gcode for a circular pocket that I would like to cut on my home built CNC. The move to the first X/Y coordinate works correctly as does the plunge on the Z axis.  However, the machine stalls at this point and will not execute the G02 instruction. I'm guessing that I missed something in my preamble, but haven't a clue what it could be.  If someone can enlighten me I would greatly appreciate it.


G90 G20 G17
M3 S22000
G04 P6.0
F30

G0 Z0.1

G0 X0.7812 Y0
G0 Z-0.25
G02 I-0.7812 J0

Kind Regards,

I don't know what the expected behavior is if you have no X/Y coordinates in your command. IIRC if you want a full circle, you can use the same coordinates as your starting point. Arguably better practice is to split the move up into two half circles.

You can try one of the following to see if it helps:

G02 X0.7812 Y0 I-0.7812 J0

or

G02 X-0.7812 Y0 I-0.7812 J0
G02 X0.7812 Y0 I0.7812 J0

I'll give this format a try and report back.

Spindle-at-speed was the issue. I had added a near function to the spindle-at-speed signal in an attempt to get away from the extra dwell after M3. However when I examined the near function input signals the feedback rate was 0 causing spindle-at-speed to never to active.

I removed all of my near function code and put spindle control back to the original configuration and the spindle-at-speed now goes active, but at a significant delta from the commanded speed based on the VFD display and the sound of the spindle. Consequently, I'm back to the additional dwell after M3. Not a real issue since this is a hobby machine and I'm not in any hurry to make cuts.

Thanks for the insight and support.

Kind regards,

The spindle-at-speed signal was the issue. The command is correct for a full circle cut. I did add P1 to insure that a full circle is cut though the documentation indicates that P1 is implied if not provided.

Thanks for you help.