13. Program Support Functions
13.26 End Point Error Check Cancellation; G69
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13.26 End Point Error Check Cancellation; G69
Function and purpose
If an illegal program is given to NC, a program error will occur.
However, the error point check cancellation command G69 can be used to escape a program
error only in the following conditions.
(1) The end point does not exist on the circumference of a circle in circular interpolation
(containing helical cutting).
(2) With tool radius compensation, the compensation amount is changed during circular
interpolation modal.
Command format
G69 (G03) X__ Y__ Z__ - - - ;
End point error check cancellation
G69
:End point error check cancellation (G69 command is unmodal.)
G03
:Commands such as circular command
X Y Z - - -
:End point of the circular commands
Though this point is illegal at usual, it will not be regarded as the
error point by using G69.
Detailed description
(1) Circular cutting (including helical interpolation)
If the end point does not exist on the circumference of a circle and G69 command is given in
circular interpolation, the circular radius changes linearly together with the angle after
movement as shown below:
Radius R
End point
Start point
Outer
circumference
Angle
θ
θ
s
θ
e
Rs
Re
θ
θ
e
Rs
Re
θ
s
0
R
Start point
Although the speed of the outer circumference is slightly faster than the commanded speed,
the angular speed is constant.
