Circular Interpolation Question

[jamie.marquis]

When milling a circular pocket F360 typically generates a series of half circles. In the below example F360 generates (2) has circles rather than the hand generated full circle down a few lines. Could someone explain the reasoning for the half circles?

Thanks!

James

G53 G0 Z0.

( ** 2D Contour1 ** )
S20000 M3
G54
A0.
G0 G49 X1. Y0. Z0.6

G1 Z0.2 F100.
Z0.0394 F34.
Z-0.25
(++++++++ From F360 ++++++++++)
G3 X-1. I-1. J0. F100.
X1. I1. J0.
(+++++++++++++++++++++++++++)
G1 Z0.6

(  )
G1 Z0.2 F100.
Z0.0394 F34.
Z-0.25
(+++++++ Manual test ++++++++++)
G3 I-1. J0. P1 F100.
(+++++++++++++++++++++++++++)
G1 Z0.6

G53 G0 Z0.
M2
%

[a.laasW8M6T]

Its not likely that Fusion is generating half circles in the actual toolpath(this can be verified by looking at the toolpath information)

more likely is the particular Postprocessor you are using is forcing the circles to be broken up, this is due to some controls not liking full circles for circular interpolation.

[seth.madore]

Due to software rounding that does occur, it was decided early on (I believe) that breaking a circle into 90 or 180 degree arcs was a safer proposition for most. You can change this setting in the post processor if you would prefer (I did the same for both my Kitamura and DMG MORI mill posts)

maximumCircularSweep = toRad(180);

Changing that to 360 will give you a complete circle. However, there is other logic that should also go into place in the onCircular section, I'll have to dig that info up, it's been a while....

[jamie.marquis]

Thanks guys for the replies. I see the lines in the post where the 180 degree arc is specified. I'll probably just leave it alone for now, the question was just out of curiosity.

@seth.madore, please don't spend any time on this, you answered the question!

Thanks!

[PatrickPowers-CGS]

it's in the post processor. For example the generic Fanuc  you can change this line

maximumCircularSweep = toRad(360);