A more elegant solution to tool length compensation was made by the introduction of the tool length offset code, G43. This G code communicates to the CNC controller to look in a special place in its memory for the length of the tool being used. As shown in the video an operator or setup person would have previously “touched off” every tool used in the program, noted the Z-distance travelled from the tool change position to the Z-zero plane on the part, and input that value in a special memory address in the controller. The controller would retrieve that value automatically when a programmed M6 tool change was encountered. The controller would then perform all of the additions or subtractions necessary to insure that the programmed value of Z0.0 would be adjusted for the tip of each tool to rest perfectly at the Z-zero part plane. This little slight of hand is called “length compensation”. The only thing the controller needs is the location in memory where the tool length is stored.