Abstract: A method for calibrating the center point of a tool attached to a robot face plate or other machine uses a calibration block having vertical and horizontal faces. The position of the tool center point is determined by moving the tool from a starting position to touch one of the faces, recording the location of the face plate and returning the tool to the starting point. This is repeated for the other surfaces. Then the tool center point can be calculated from the recorded locations. Also disclosed is a calibration block having a centering area with four walls arranged to form a parallelogram and a leveling area with four walls arranged to form an x, y coordinate axis.