The jig is up

Pressure-treated 1x8 plates were cut to support each leg, and the permanent pressure-treated 2x4 legs were cut and attached using two 3/8” GRK RSS construction fasteners (which are equivalent to 1/2” lag screws). Thanks to the sage advice of a knowledgable friend, 2x4 sections are sistered to each leg between the lvl and ground plate. Adding the sistered pieces reduces the bearing weight on the screws holding the legs attached to inner face of the jig sides. Cross-bracing between legs resists racking.

Surprisingly, multiple corner-to-corner measurements revealed that the jig was off by just 3/16” before correcting for square. A come-along attached to temporary screws pulled the jig into square, and the specified 3/4” plywood corner gussets were fastened into place.

Building, reinforcing, leveling, and squaring the jig took longer than hoped. However, ensuring a sturdy and true strongback now could save headaches later.