Cricket Valley: Miter and Saw Blade Bevel Angles

Photo courtesy of Tim Uhler

Changing the Cricket Valley Rafter Pitch to 4-1/16 over 12

Summary of Cricket Valley Rafter Angles

 Cricket Valley meets 12 ÷ 12 Slope Angle on the Stick = 20.93913° Saw Miter Angle = 69.06087° Blade Bevel Angle = 23.83230° Cricket Valley meets 7 ÷ 12 Slope Angle on the Stick = 36.86989° Saw Miter Angle = 53.13011° Blade Bevel Angle = 24.42507°

Compound Angles on the Jack Rafters

 Jack Rafter meets Level Line on the 12 ÷ 12 Slope : All the angles are 22.89394° as measured on the rafters. Miter Angle = 90° - 22.89394° = 67.10606° , Saw Blade Bevel = zero Jack Rafter meets 4 ÷ 12 Cricket Valley : These are standard angles with respect to a Level Plane. Plumb Line = 22.10606° , Saw Blade Bevel = Deck Angle = 55.15010° Angles on the face set in the Cricket Valley Roof Plane : Miter Angle = 57.17297° , Saw Blade Bevel = Backing Angle = 12.41795° Check : Angle on the plumb face created by cutting the Compound Angle = arccos (sin 22.10606° sin 57.17297°) = 71.56505° (complementary to the 4 ÷ 12 Pitch Angle)

 Jack Rafter meets Oblique Line on the 7 ÷ 12 Slope : The angle on the stick on the face set in the plane of the roof = 90° - 57.17297° = 32.82703° Dihedral angle at Cricket Valley Roof Plane meets 7 ÷ 12 Slope = 36.84301° The cutting angles from the face set in the roof plane are: Miter Angle = 57.17297° , Saw Blade Bevel = 90° - 36.84301° = 53.15699° Calculating the angles on the Jack Rafter side (plumb) face: LAG Program Entries : (Set Select Entry Mode to Angular) Main Pitch : 36.84301° Adjacent Pitch : 90.00000° Total Deck Angle : 32.82703° LAG Program Returns : R1 = 22.10606° (the angle on the stick ; Miter Angle = 90° - 22.10606° = 67.89394°) C5m = 30.25644° (the Saw Blade Bevel , 7 ÷ 12) 90° - P2m = 38.87303° (angle on the face created by cutting the Compound Angle) Check : arccos (sin 57.17297° sin 67.89394°) = 38.87302°