14 The Tool Compensation
If G28 or G30 is programmed (followed by G29) between two blocks in offset mode, the compensation vector will be deleted at the end point of the block it positions the tool to the intermediate point, the tool will move to the reference point, and the vector will be restored at the end point of the returning block G29.
For example:
...G91 G17 G41...
N110 G1 X80
N120 G28 Y80
N130 G29 Y0
N140 X80 Y50
...
Fig.
A new compensation value can also be
called at address D in offset mode. In the
event of a reversal in the sign of the radius, the direction of motion along the contours will be reversed (see earlier).
Otherwise, the following procedure will
be applicable. The compensation vector will be calculated with the new radius value at the end point of the interpolation,
in which the new address D has been
programmed. Since the compensation vector has been computed with the previous radius value at the start point of that block, the path of the tool center will not be parallel to the programmed path. A new radius compensation value can be called at address D in a circular interpolation, too, this time, however, the tool center will be moving along an arc with a variable radius.
A special instance of the foregoing is canceling or setting up the compensation with D00 or Dnn, respectively, while in offset mode. Notice the difference in tool paths with reference to the following example, when the compensation is set up with G41 or G42 and canceled with G40, or when the compensation is set up and canceled by programming D.
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