Link to all of the Timber FRaming Angles Help Files
The Hip-Valley Roof Ratios Angle Formulas for Rafters Rotated into the Roof Surface Plane were developed by Sim Ayers.
The Hip-Valley Roof Ratios Angle Formulas were developed by Joe Bartok.
The Timber Framing Hawkindale Angle Formulas were developed by Rees Hawkins Acheson from the Martindale Hip and Valley Roof Angles.
The Hawkindale angles were based on the book by Frank L. Martindale "Bevel Angles for Three Dimensional Connections" 1948 that was based on the book "Hip and Valley Design" by H. L. McKibben and L. E. Gray published in 1912.