Calculated Industries 4090 - Manual (Page 92)

U
SER
’
S
G
UIDE
— 91
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 DISPLAY
1. Enter Pitch, Run, and On-Center spacing:
o o 0.
9 i p PTCH 9
INCH
6 f 9 i R X 6
FEET
9
INCH
1 8 i j j JKOC 18
INCH
2. Find Jack rafter lengths and cut angles:
j JK1 6
FEET
6-3/4
INCH
j JK2 4
FEET
8-1/4
INCH
j JK3 2
FEET
9-3/4
INCH
j JK4 0
FEET
11-1/4
INCH
j JK5 0
FEET
0
INCH
j PLMB 36.8699°
j LEVL 53.1301°
j CHK1 45.°
3. Reset On-Center spacing to 16 Inches:
1 6 i j JKOC 16
INCH
STORED