G64 Path Blending
http://linuxcnc.org/docs/html/gcode/gcode.html#sec:G61-G61_1G64 <P- <Q->>
P - motion blending tolerance
Q - naive cam tolerance
G64 - best possible speed.
G64 P- <Q- > blending with tolerance.
G64 - without
P means to keep the best speed possible, no matter how far away from the programmed point you end up.
G64 P- Q- - is a way to fine tune your system for best compromise between speed and accuracy. The P- tolerance means that the actual path will be no more than P- away from the programmed endpoint. The velocity will be reduced if needed to maintain the path. In addition, when you activate G64 P- Q- it turns on the naive cam detector; when there are a series of linear XYZ feed moves at the same feed rate that are less than Q- away from being collinear, they are collapsed into a single linear move. On G2/G3 moves in the G17 (XY) plane when the maximum deviation of an arc from a straight line is less than the G64 P- tolerance the arc is broken into two lines (from start of arc to midpoint, and from midpoint to end). those lines are then subject to the naive cam algorithm for lines. Thus, line-arc, arc-arc, and arc-line cases as well as line-line benefit from the naive cam detector. This improves contouring performance by simplifying the path. It is OK to program for the mode that is already active. See also the Trajectory Control Section for more information on these modes. If Q is not specified then it will have the same behavior as before and use the value of P-.
G64 P- Example Line (set path following to be within 0.015 of the actual path)
It is a good idea to include a path control specification in the preamble of each G code file.
