Smithy CNC Mills - Manual (Page 80)

SmithyCNC Programmer’s Reference Manual: Coordinate System 8-9
These tests did not study the effect of re-reading the var file while they contain
numbers. This could cause problems if g92 offsets had been removed with
g92.1 but the var file still contained the previous numbers.
It is this complexity that causes us to say that G92 values must be treated as
temporary. They should be used to set global short term offsets. The G54-59.3
coordinate systems should be used whenever long lasting and predictable off-
sets are needed.
8.5 Sample Program Using Offsets
This sample engraving project mills a set of four .1 radius circles in roughly star
shape around a center circle. We can setup the individual circle pattern like this.
G10 L2 P1 x0 y0 z0 (ensure that g54 is set to machine
zero)
g0 x-.1 y0 z0
g1 f1 z-.25
g3 x-.1 y0 i.1 j0
g0 z0
m2
We can issue a set of commands to create offsets for the four other circles like
this.
G10 L2 P2 x0.5 (offsets g55 x value by 0.5 inch)
G10 L2 P3 x-0.5 (offsets g56 x value by -0.5 inch)
G10 L2 P4 y0.5 (offsets g57 y value by 0.5 inch)
G10 L2 P5 y-0.5 (offsets g58 y value by -0.5 inch)
We put these together in the following program.
(a program for milling five small circles in a diamond shape)
G10 L2 P1 x0 y0 z0 (ensure that g54 is machine zero)