Special function: circle radius compensation in combination with G164

In certain situations, circle center point compensation (G165) can lead to an unfavorable shift in the programmed circle center point and thus the circle's position. Such unfavorable situations can occur when the circle starting, and destination points are close together and the circle almost corresponds to a programmed full circle. Such a circle with specification of the destination point with and without circle center point compensation (G165/G164) is programmed in the following example. To simulate the resolution error in the post-processor, when circle center point compensation is active the circle's destination point is shifted by 0.1μm in each case in the x and y directions in comparison with the starting point. The circle with G165 is rotated about the starting point and the position of the corrected circle center point M_K shifts very considerably in comparison with the programmed center point M.

N10 G00 G90 X0 Y0 Z0
N20 G01 X-50 Y0 F20000
N30 G01 X0
N40 G165 G02 X0.0001 Y0.0001 J200
N50 G01 Y50
M30
N10 G00 X0 Y0 Z0
N20 G01 X-50 Y0 F20000
N30 G01 X0
N40 G164 G02 X0.0 Y0.0 J200
N50 G01 Y50
N60 M30

In such cases a better result can generally be achieved with inactive circle center point compensation and setting of the "max_radius_diff_circle" > 0 and "max_proz_radius_-diff_circle" channel parameters. The programmed circle center point is not changed by the function and the circle radius difference is transferred in a linear fashion from the starting radius to the destination radius via the circle's angle.

If the circle radius deviations lie in the order of magnitude of the resolution accuracy, the circle distortions and dynamic effects are generally negligible.

For a full circle, here also the circle starting and destination points must be identical!