good to know the standards- i had just centered the pegs in the mortises and tenons as it looked as if that much behind the peg in the tenon and that much 'in front' of the peg in the cheek of the mortise would hold. in this case, with this tree, the tenons from the heart of the posts are definitely of tougher wood than the edges of the beam.
so the peg hole ideally ought to be 1 1/2 inches in from the shoulder of the tenon? i'm assuming that's to the edge of the peg hole, so 2' to the center? that might work. again though, would there be a pressing need for pegs in this application- m&t joint between a 10' 10X8 load bearing beam (weight of a 10X12 deck and a timber pergola, plus dancers) and 3' 10X7 supporting posts?
