Here you can see some of the pins inserted into the Head Tube and Top Tube and Down Tube.  I used four pins in each lug.  In the BB I used three for the Seat Tube and 3 for the Down Tube.  These go all the way through the lug and tube.  The taped on the nail when tapped in slightly, holds the position of the tube and lug.  When the whole frame is pinned it is pretty stiff and stable.