13. Program Support Functions
13.23 3-dimensional Coordinate Conversion; G68.1/G69.1
464
Precautions related to arc command
If the first command after the 3-dimensional coordinate conversion command was an arc shape,
and the center of the arc did not change before and after the 3-dimensional coordinate
conversion, an arc is drawn. However, an error will occur in the following cases:
(1) For the arc in which the arc center is specified with I and J, if the center coordinate has been
deviated followed by the 3-dimensional coordinate conversion, a program error (P70 Major arc
end position deviation) will occur.
Current
position
Y
X
End point
(X 100, Y 0)
Arc center
(X 50, Y 0)
Y
Y'
(X 100, Y 0)
Arc center
(X' 50, Y' 0)
End point
(X' 100, Y' 0)
X
X'
Program error
Example in which program error (P70) occurs
G90 G28 X0 Y0 Z0 ;
F3000 G17 ;
G68.1 X100. Y0. Z0. I0 J0 K1 R0. ;
G02 X100. I50. ;
No 3-dimensional coordinate conversion
In 3-dimensional coordinate conversion
Current
position
(2) For the arc in which the arc radius is specified with R, If the center coordinate has been deviated
followed by the 3-dimensional coordinate conversion, a program error (P71 Arc center
calculation disabled) will occur.
Y
X
End point (X 100, Y 0)
Y
Y'
(X 100, Y 0)
End point
(X' 100, Y' 0)
X
X'
Program error
Example in which program error (P71) occurs
G90 G28 X0 Y0 Z0 ;
F3000 G17 ;
G68.1 X100. Y0. Z0. I0 J0 K1 R0. ;
G02 X100. R50. ;
No 3-dimensional coordinate conversion
In 3-dimensional coordinate conversion
Radius = 50
Radius
≠
50
Current
position
Current
position