Easy way to zero z for production

If you are making a bunch of small parts, and x y 0 is going to be cut out or is in a waste area, jog your bit over the spot, and with your router on, jog down by thousandths until you hear the bit contact the surface, then jog it up until the contact noise stops, and begin your carve.
Then jog over the width of the piece and start again.
Works fine for me for carving LOTS of little pieces.