Jack Rafter intersects Hip or Valley Rafter
Study of Shelf Cut following the line parallel to the long axis of the Hip or Valley Rafter


Jack Rafter intersects Valley Rafter
Wireframe sketches of Shelf Cut (Square Cut) on the Jack Rafter and housing on the Valley Rafter
Exploded view if sequence of Square Cuts taken through the Jack Rafter
Tetrahedron modeling the Compound Angle of the Shelf Cut for the Jack Rafter
P2 ... Side Cut Angle on the shoulder of the jack rafter set in the surface of the roof, at the intersection of the jack rafter and the Valley rafter.

C5 ... Backing Angle. Saw Blade Bevel Angle to make the cut along the miter line created by angle P2.

P6 ... Angle produced by plane of the shelf cut intersecting the plumb face of the jack rafter, or Backing Angle C5 as viewed when projected to the plumb face of the jack rafter through angle 90 P2.

R4P ... Valley Rafter Side Cut Angle, traced on the unbacked shoulder of a Valley rafter, where the Valley intersects the plumb plane of a wall perpendicular to the roof ridge line (or, a plane parallel to the plumb face of a jack rafter).

A5P ... 90 A5P is the dihedral angle measured between the lower (unbacked) shoulder of a Valley rafter and the plumb plane of a wall (a plane parallel to the plumb face of a jack rafter) perpendicular to the roof ridge line.

Joe Bartok