Smithy CNC Mills - Manual (Page 28)

SmithyCNC Programmer’s Reference Manual: G Codes 2-13
Rotational axis words are allowed in canned cycles, but it is better to omit them. If rotational
axis words are used, the numbers must be the same as the current position numbers so that
the rotational axes do not move.
All canned cycles use X, Y, R, and Z numbers in the NC code. These numbers are used to
determine X, Y, R, and Z positions. The R (usually meaning retract) position is along the axis
perpendicular to the currently selected plane (Z-axis for XY-plane, X-axis for YZ-plane, Y-axis for
XZ-plane). Some canned cycles use additional arguments.
For canned cycles, we will call a number "sticky" if, when the same cycle is used on several
lines of code in a row, the number must be used the first time, but is optional on the rest of
the lines. Sticky numbers keep their value on the rest of the lines if they are not
explicitly programmed to be different. The R number is always sticky.
In incremental distance mode: when the XY-plane is selected, X, Y, and R numbers are treated
as increments to the current position and Z as an increment from the Z-axis position before the
move involving Z takes place; when the YZ or XZ-plane is selected, treatment of the axis words
is analogous. In absolute distance mode, the X, Y, R, and Z numbers are absolute positions in
the current coordinate system.
The L number is optional and represents the number of repeats. L=0 is not allowed. If the
repeat feature is used, it is normally used in incremental distance mode, so that the same
sequence of motions is repeated in several equally spaced places along a straight line. In
absolute distance mode, L>1 means "do the same cycle in the same place several times,"
Omitting the L word is equivalent to specifying L=1. The L number is not sticky.
When L>1 in incremental mode with the XY-plane selected, the X and Y positions are deter-
mined by adding the given X and Y numbers either to the current X and Y positions (on the
first go-around) or to the X and Y positions at the end of the previous go-around (on the
repetitions). The R and Z positions do not change during the repeats.
The height of the retract move at the end of each repeat (called "clear Z" in the descriptions
below) is determined by the setting of the retract mode: either to the original Z position (if that
is above the R position and the retract mode is G98, OLD_Z), or otherwise to the R position.
See Section [sub:G98,-G99:-Set]
It is an error if:
* X, Y, and Z words are all missing during a canned cycle,
* a P number is required and a negative P number is used,
* an L number is used that does not evaluate to a positive integer,
* rotational axis motion is used during a canned cycle,