Dave, I'm am a little confused by your description of "Straddle a 3" wide board" but I will try to help.. The beadlock will join anything that biscuit joiner can handle. It registers on one face much like a biscuit joiner. For thicker pieces, you add shims to move the bushings away from the the registering fence. Technically, you can even replace the 1/4-20 bolts with longer ones, use a thicker shim, and be able to place the mortise further "inland". Thus, you could use it to form a joint of a
1" apron into the center of a 3" leg. The jig is well constructed, accurate and affordable. I recall only one jig ever being returned to McFeely's and that involved someone trying to use 1/2 drill through 3/8 diameter holes. ???? You won't regret the purchase of this jig! Darin Lawrence, Technical Director McFeely's Square Drive ScrewsPat Barber wrote: