The large holes are required if your strongback is not prefectly straight. The looseness allows the forms to be perfectly lined up on a less then perfect SB.

I used a sting to draw a straight line end to end on the SB (which may not be exactly parallel to the SB edges) to initially line up the forms. Then use string, line of sight or what ever method you come up with to assure perfect alignment in all directions....some folks here have even used lasers. The large holes give the 'wiggle room' you may need during this final adjustment.

: I am to the point where I will set up my strong back. I am building a
: Guillmot. I cut the holes in the forms to the lines on the plans. The
: resulting hole is very loose on my 2x4. How should I set up the forms with
: the large?? holes? The comments previously regarding strong back setup
: were very encouraging. Just want to get off on the right foot Thanx, Steve