Matthias Wandell is a genius, and his Screw advance box joint jig is a marvel.
I made this finger joint with the jig built by his plans (I upgraded it recently).
The ruller is Metric, not Inch. every finger is 2.5mm thick ׂ(=0.09 inch)
The stock is 6mm thick, maple. came up perfect with no gaps at all in first try.
Making all the finger joints for the box took less than 2 min.
-- Only by the 4th time I realized how it was suppose to be done in the first place.