Tool length offsets (TLOs) amount to nothing more than the jog distance the Z-axis must
travel from its fully retracted position to the position where the cutter makes contact
with a Z-zero reference surface (usually the top surface of the workpiece). This is
accomplished by "touching off" each cutter on the reference surface (using a
feeler gage) and loading the jog distance into the appropriate TLO register. When each
tool is "called," the appropriate TLO is accessed and used to offset the Z-axis
Procedures for Setting TLOs
Make sure the quill is fully retracted and the Z-axis register reads zero at that
position. If necessary, zero out the Z-axis register (in
Load each cutter into a toolholder, making sure it is securely held so it won't slip in
Adjust the height of the table so that the longest cutter/toolholder assembly can be
installed in the spindle without interfering with anything.
Press the HAND WHEEL OPERATION key and press Z and keys to
make the Z-axis active.
Hand wheel the cutter to the Z-reference plane, using a feeler gage such as a
0.100" gage block.
Press the EDIT program key and move the cursor to highlight the "L"
parameter in the appropriate Tool Definition block.
Press the DATA TRANSFER key to transfer the jog distance displayed in the Z-axis
counter into the Tool Definition block. Then press the EOB key.