G43, G44, and G49 Tool Length Offset

G43, G44, and G49 Tool Length Offset¶

The tool length offset function adds (G43) or subtracts (G44) the amount stored in the tool offset data memory to or from the Z coordinate values specified in a program to offset the programmed paths according to the length of a cutting tool.
If Tool length offset value is negative, Tool Length Offset direction will be reversed.
It is a modal command and is active until it is cancelled (G49).

Syntax:
G43 H3 Z0 - Using Tool #3 Length as the offset, Moving Z axis to position 0 (after adding offset amount)
G44 H4 Z100 - Using Tool #4 Length as the offset, Moving Z axis to position 100 (after subtracting offset amount)

The offset amount is specified in the Tool Data table, so it is necessary to define tool number using the H argument.
During G43/G44 decoding, the specified tool length and length wear amount is read from the Tool Data table and the combined value is added to the Active Offsets table.
For every motion block, the Tool Length Offset amount is added or subtracted from the calculated Z axis position.
This command performs motion, so it requires at least Z position to be defined in the same line.

G43 H1 Z-20 - Enables Z offset by Tool #1 length amount (-3) and performs motion to Z-20 position after adding Tool #1 Length Offset. Actual calculated Z position -23.
G01 Z-30 - Performs motion to Z-30 position (Actual position Z-33).
G44 H2 Z-30 - Enables Z offset by Tool #2 length amount (4) and performs motion to Z-30 position after subtracting Tool #2 Length Offset. Actual calculated Z position -34.
G01 Z-40 - Performs motion to Z-40 position (Actual position Z-44).