the Zero Null Feature
Zero Null feature helps with one of the more difficult
setup problems, centralizing the part at the same
time as aligning a feature on the part during the
zero null, clamp the part firmly and centralize
the spindle with the shotpin in a position eyeball
close to the desired position.
the four lock screws in the back as shown and rotate
the spindle to the desired postion.
the four screws and you are done.