Rockwell Automation 8520-GUM 9/Series CNC Grinder Operation and Programming Manual Documentation Set - Manual (Page 631)

Turning Operations
Chapter 18
18-15
The format for the G33 thread grinding operation is:
Parallel thread G33Z__ F__ Q__;
E
Tapered thread G33X__Z__ F__ Q__;
E
Face thread G33X__ F__ Q__;
E
Where : Is :
X the end point of the thread grinding move in the X-axis. This parameter can be
an incremental or absolute and radius or diameter value. If not present there
must be a Z parameter. If an X parameter is present, it indicates either a face,
tapered, or lead-in thread. When used in a G33 block without a Z parameter, a
facing thread is made parallel to the X-axis at the Z-axis position prior to the G33
block. X values can be entered as a radius or a diameter value. X can also be
programmed as an incremental or absolute value. The initial minor diameter of
any straight or tapered thread is determined by the position of the X-axis prior to
the G33 block.
Z the end point of the thread grinding move in the Z-axis. This parameter can be
an incremental or absolute value. If not present there must be an X parameter.
When using a Z parameter in a G33 block without an X parameter the threading
pass is made parallel to the Z-axis at whatever X position the grinding wheel
edge was at prior to the G33 block. Z parameter is always entered as a radius
values regardless of the current mode.
E F This parameter may be entered by using either an E- or F-word. It represents the
thread lead along the axis with the largest programmed distance to travel to
make the thread cut. It is mandatory when cutting any threads.
If the E-word is programmed, its value (sign ignored) is equal to the number of
threads per inch or inches per thread (determined in AMP) regardless of whether
inch or metric mode is active at the time.
If the F-word is programmed, its value (sign ignored) is the thread lead in inches
per revolution or millimeters per revolution, depending on the mode in which the
control is operating.
Q an optional parameter that provides a relative value for the start offset angle of
the thread. Its primary use is in grinding multi-start threads. For example, if a
threading pass were made with a value of zero here, and then followed by
another pass with a value of 180 then the second pass is started 180 degrees
from the first resulting in a two start thread. If two more passes are then made,
one with a parameter value of 90 and one with a value of 270, the result would
be a four start thread.