I work alone, so I often have to come up with jigs as extra “hands.” If I find my cabinet-opening diagonals aren’t equal, here’s what I do to square and hold them till permanent connections are in place.
As shown in the drawing below, I measure the adjoining sides A and B. Then I square each of these numbers and add them together. The root of this total is the diagonal C.
At the C dimension, I adjust and clamp a sturdy bar gauge made from a ripped 2x4. Then I rack the cabinet box until the gauge fits into what was the lesser diagonal. Now I’m ready to make my mechanical connections.
Michael Boothby, Langton, Ontario, ca
From Fine Homebuilding 224, pp. 24
November 10, 2011