Hi kolokithas,
Here is the real TLO scoop. When you set up a CNC Mill, you must have a z home position to reliably use TLO. This requires a home switch on the top of the Z axis travel and establishes Z zero on startup. The next thing that you must establish is what surface you wish to reference all measurments. this surface can be the machine table or a fixture plate. You must also devise some way of holding your tools in a repeatable manner. This can be done by installing stop collars on your cutters. Once this is done, you home the machine then zero Z. Next you install each tool in turn and run the Z down until the tool tip contacts the table or fixture. Use a thin piece of paper to feel when contact is made. Note the travel distance for each tool and set up these distances in the TLO table. Now when you call a tool with G43 the controller compensates for the different Z distances to reach the table or fixture. The next thing you must program is the work coordinate offset (WCO) table to allow for various material thickness. The WCO distance moves Z Zero in the opposite direction to allow for the material being cut. Another option that does not use WCO is to set the TLO of the shortest tool to zero and use the length difference for the rest of the tools. When you begin to work, you touch the top of the material with tool #1 then zero Z. install the working tool and call up the appropriate offset with G43 T# and run. This method does not require home switches.
I hope that I have been of some help.
Dennis  |