8 Basic CNC Programming
8.4 NC Codes
118
8.4.11.
L Code: Angle of Arc Resolution, Loop Counter
The L code is used in three unrelated ways, as listed below.
Section Contents: Angle of Arc Resolution, Loop Counter
Description
Section
Page
To specify the resolution of an arc or circle
8.4.11.1 L Code: Angle of Arc Resolution
As a loop or program counter
8.4.11.2 L Code: Loop and Program
Counter
By default, an L code that is not specifically used as a counter is treated as specifying the arc/circle
resolution factor.
8.4.11.1.
L Code: Angle of Arc Resolution
When specifying an arc or circle, the L code specifies the angle of arc resolution in circular interpolation
programming. When the system executes a circular motion, it splits the arc into a series of line segments
to approximate the circle. The L code specifies the resolution in terms of the angle in degrees across
which a line segment approximates a portion of the arc. Setting a low value of L increases the resolution
of the arc or circle, and thus creates a smoother cut. However, very fine resolutions may cause the
milling center to hesitate while cutting.
The table below illustrates the effect of the L value.
Info Table: L Code Specifying Angle of Arc Resolution
High Value of L
Low Value of L
Example
Resolution
Resolution is low; the approximated circle is
made up of few lines.
Resolution is higher; the approximated circle is
made up many lines.
Default Settings
The default setting for the milling center is 2 degrees, and typically this will work quite well. The L code
can be a fraction of a degree (such as L0.5), but it must be large enough so that the milling center will
move at least the minimum motion distance (0.0005") on each of the straight line motions.
