The Zero Z height tool is a must have for every CNC user. Makes resetting Z height in Mach3, after tool changes or material changes, a breeze. Thanks Tweakie for an excellent tutorial.
Tool position setting Part II.
Build in 'CNC ROUTER BUILDS' published by Tweakie, Apr 27, 2014.
The method used for tool position setting is a matter of personal choice but this is what I do.