Jack Rafters - Using Other Than 16 Inch On-Center Spacing - Calculated Industries Sheet Metal/HVAC Pro Calc User Manual

Jack Rafters — Using Other Than 16 Inch On-Center Spacing
A roof has a 9/12 Pitch and a Run of 6 Feet 9 Inches. Find the Jack
rafter lengths and cut angles at 18-Inch (versus 16-Inch) On-Center
spacing. The On-Center spacing is used for both Regular and
Irregular Jack calculations.
KEYSTROKE
1. Enter Pitch, Run, and On-Center spacing:
o o
9 i p
6 f 9 i R
1 8 i j j
2. Find Jack rafter lengths and cut angles:
j
j
j
j
j
j
j
j
3. Reset On-Center spacing to 16 Inches:
1 6 i j
PTCH 9
X 6
FEET
JKOC
STORED
JK1 6 6-3/4
FEET
JK2 4 8-1/4
FEET
JK3 2 9-3/4
FEET
JK4 0 11-1/4
FEET
JK5 0
FEET
PLMB 36.8699°
LEVL 53.1301°
CHK1 45.°
JKOC 16
U ' G
SER S UIDE
DISPLAY
0.
INCH
9
INCH
18
INCH
INCH
INCH
INCH
INCH
0
INCH
INCH
— 91