From the Set Tool Offsets menu, press WORK> . This takes you to the Set Work Offsets menu.
Use the pulse wheel to jog the X and Z Axes to approximately 0.20" (5.1 mm) away from the face of the workpiece.
Use the LEFT arrow key to select the .001 jog increment.
Put a sheet of paper  between the tool and the workpiece.
Carefully move the tool to the part.
Stop when the tool is near as possible to the workpiece, but you can still move the paper.
Use the axis selection thumb knob and select the Z Axis.
Press SET Z to record the Z-Axis position in the offset table.
Be aware: Many service and repair procedures should be done only by authorized personnel. The service technicians at your Haas Factory Outlet (HFO) have the training, experience, and are certified to do these tasks safely and correctly. You should not do machine repair or service procedures unless you are qualified and knowledgeable about the processes.
Danger: Some service procedures can be dangerous or life-threatening. DO NOT attempt a procedure that you do not completely understand. Contact your Haas Factory Outlet (HFO) and schedule a service technician visit if you have any doubts about doing a procedure.