8 Basic CNC Programming
8.4 NC Codes
106
Multiple coordinate systems can be useful for different size workpieces, or for special set-up conditions.
There are seven coordinate system codes. One of these codes (G53) is used for rapid traverse motion to
specified machine coordinates. The other six codes allow you to make up to six individual parts on the
same workpiece by specifying different work coordinate systems for each part.
The coordinate system codes are G54 through G59, referring to coordinate systems 1 through 6
respectively. These coordinate systems may be set through the Coordinate Systems command on the
Setup Menu.
Info Table: The Coordinate System Group
G 53
For rapid traverse motion to specified machine coordinates.
G Code
G54
G55
G56
G57
G58
G59
Coordinate
System
Activated
1
2
3
4
5
6
8.4.6.8.
The Polar Programming Group
The Polar Programming Group codes allow you to perform programming operations based on polar
coordinates (as opposed to Cartesian coordinates).
The supported Polar Programming codes are listed in this table.
Info Table: Polar Programming Group
Code
Function
G15
Polar programming OFF
G16
Polar programming ON
Using polar coordinates allows you to specify a radius and an angle by specifying a G16 code (polar
programming on), then X, Y, and Z codes. The X code specifies the radius, the Y code specifies the angle
in degrees, and the Z code specifies the height at the end of the cut, as in linear interpolation.
A G15 code is used to cancel the polar programming mode.
Polar programming can be used in both absolute and incremental programming modes. The point taken
to be the center of the commanded motion depends on whether using absolute or incremental mode,
and on whether or not the radius (X) value is specified, as follows:
Info Table: Polar Programming in Absolute and Incremental Modes
Mode
Activated by
Center Point Location if Specifying
Radius (X) and Angle (Z) Codes
Center Point Location if Specifying on
Angle (Y) Code
Absolute
G90
The defined workpiece origin
The current location
Incremental
G91
The current location
Polar programming is especially useful when writing programs for machining bolt holes. An L code (see
8.4.11 L Code: Angle of Arc Resolution, Loop Counter, pg. 118) can be used as a multiplier for the angle
value. See the following example.
NC Code Example:
G0 X0 Y0 Z0.07
