Smithy CNC Mills - Manual (Page 73)

SmithyCNC Programmer’s Reference Manual: Coordinate System
SmithyCNC Programmer’s Reference Manual: Coordinate System 8-2
COORDINATE SYSTEM AND G92 OFFSET
8.1 Overiew
You have seen how handy a tool length offset can be. Having this allows the
programmer to ignore the actual tool length when writing a part program. In
the same way, it is really nice to be able to find a prominent part of a casting or
block of material and work a program from that point rather than having to take
account of the location at which the casting or block will be held during the
machining.
This chapter introduces you to offsets as they are used by the EMC. These
include;
* machine coordinates (G53)
* nine offsets (G54-G59.3 )
* a set of global offsets (G92).
8.2 The Machine Position Command (G53)
Regardless of any offsets that may be in effect, putting a G53 in a block of code
tells the interpreter to go to the real or absolute axis positions commanded
in the block. For example
g53 g0 x0 y0 z0
will get you to the actual position where these three axes are zero. You might
use a command like this if you have a favorite position for tool changes or if
your machine has an auto tool changer. You might also use this command to get
the tool out of the way so that you can rotate or change a part in a vice.
G53 is not a modal command. It must be used on each line where motion based
upon absolute machine position is desired.