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92 — S
HEET METAL/HVAC PRO CALC
Irregular Hip/Valley and Jack Rafters — Descending, with
On-Center Spacing Maintained
You’re working with a 7/12 Pitch and half your overall Span is 4
Feet. The Irregular Pitch is 8/12, and 16-Inch On-Center spacing is
maintained on both sides. Complete the following steps:
(1) Find the length of the Common rafter;
(2) Reset calculator to 16-Inch On-Center spacing;
(3) Enter the Irregular Pitch; find the length of the adjoining
“Irregular” Hip (or Valley) and the cut angles;
(4) Find the Jack lengths on the “Irregular” Pitch side (16-Inch
On-Center spacing);
(5) Find the cut angles;
(6) Find the Jack lengths on the “Regular” Pitch side (16-Inch
On-Center spacing);
(7) Find the cut angles.
KEYSTROKE DISPLAY
1. Find Common rafter length:
o o 0.
7 i p PTCH 7 INCH
4 f R X 4 FEET 0 INCH
d R 4 FEET 7-9/16 INCH
2. Enter On-Center spacing:
1 6 i j JKOC 16 INCH
3. Find Irregular Hip/Valley rafter length and cut angles:
8 i Ç H IPCH 8 INCH
H IH/V 5 FEET 9-11/16 INCH
H PLMB 23.70162°
H LEVL 66.29838°
H CHK1 41.18592°
H CHK2 48.81408°
4. Find Irregular Jack lengths:
Ç j IJOC 16
INCH
j* IJ1 2 FEET 9-5/8 INCH
j IJ2 1 FEET 4-13/16 INCH
j IJ3 0 FEET 0 INCH
*Note: It is not necessary to continue pressing Ç when displaying each Jack rafter
size.
(Cont’d)
STORED
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