Hi TB and everyone:
I will try and clarify if I can, sometimes what was done by the "old experts" is not easy to describe, but I know of examples standing today built in 1865 that is remarkably straight and true.
picture if you can your ring of upper plate timbers whether they are sitting on stone walls or vertical posts --no problem--now the bottom chord of each the trusses mortised into the opposing plates and pinned, or if you wish dovetailed and wedged. The top of each chord is flush with the top of the plate at the point of fastening
At a predetermined distance in from the plate the sloping truss timbers gracefully rise towards the peak from each end terminating , well mated and fastened at their tops, the bottoms are set into the top of the chord in a shallow seating and pinned securely.
In my example a 1" wrought iron rod drops down from the peak extending through the bottom chord to hold it perfectly straight.
Being that the truss is framed in a predetermined total distance from the extreme outer edge of the plate it allows enough room for the thickness of a squared timber to be placed on top of the sloping truss timbers (and listen carefully now) -these timbers are running the length of the building one on each side of the trusses and securely fastened there.
From underneath the sloping truss timbers and right where the aforementioned square timbers set an angled web supporting brace is gracefully set in place mortised and tenanted and pinned, (these braces are at a right angle to the bottom of the sloping truss timber).
Now all the rafters are set in mortises at their feet while their gently tapered lengths are supported about 1\2 the distance , to the peak, and lie above the trusses, what a sight!
this may not work for you and your plans, but variations of the above I am sure will work.
NH
