The Virtual Machine Shop

length compensation (plus, minus, cancel)

The G43 and G44 code words are used to adjust for length differences in the tool magazine. Applying these codes changes the effective Z=zero level of the part so that each tool touches off at the same place. The length of each tool has to be set up in a controller memory address. The program block calls for the length compensation and describes where that data is stored using the H word.


N1000 G43 H3 (#3 is just one of many memory locations)

Whatever value is stored in location #3 is added to the "distance to go" from tool change position to Z=zero. Note that the Z movement downward is a negative (or minus value). Therefore "adding" a tool length offset in effect "subtracts" from the relative distance. Ergo the concept of "adding" a tool length offset to make the distance shorter. G44 does just the opposite of G43 in that it "subtracts" the tool length. G44 is rarely used. G49 cancels length compensation.