Tetrahedron Slice -- Hucks jig for Roof Framing Angles

I've seen Hucks jig for roof framing angles and always knew it was a tetrahedron slice from the jack rafter side cut. I had some left over 6x6 from a recent job and decided to cut the 6x6 into Hucks jig for hip roof framing angles. Mathematically, it's called a Trirectangular Tetrahedron. Whatever you call it, Huck's done a great job in developing a jig that's useful on the jobsite. It will give you the miter angles for Purlin Rafters, Frieze Blocks, Bird Blocks or Square Tail Fascia Miter Angles.

Hopefully, this drawings will clear up the purpose of Hucks jig. It's a piece of wood representing the tetrahedron slice of the jack rafter side cut. For a 8:12 pitched roof you draw the jack rafter miter on the side of the material and then set your saw to 45° to cut the cheek cut for the jack rafter. Hucks jig is a slice from the jack rafter side cut.

Tetrahedron Slice unfolded showing the hip roof framing angles from Hucks jig.

1. Rafter Slope Angle
2. Jack Rafter Bevel Angle
3. Purlin, Frieze Block and Square Tail Fascia Miter Angle
4. Hip Rafter Slope Angle
5. Hip Rafter Backing Angle
6. Hip Rafter Square Tail Miter Angle