PowerTec 80008 Instruction Sheet

INSTRUCTION SHEET
RAFTER FRAMING SQUARE
The long arm of the square is the "body", the short arm of the square is the
"tongue". The side of the square with the brand name stamped on it is the
"face". The reverse side is the "back".
Rafter Framing Rule
• The first line of figures gives the length of common rafter for one foot run.
• The second line of figures gives the length of hip or valley rafters for one
foot run.
• The third line of figures gives the length of first jack rafter and the difference
in the length of the other spaced 16 inches on centers.
• The fourth line of figures gives the length of first jack rafters and the
difference in the length of the others spaced 24 inch centers.
• The fifth line of figures gives the side cut of jack rafters against hip or
valley rafters.
• The sixth line of figures gives the side cut of hip or valley rafter against the
ridge board of deck.
EXAMPLES
If a roof raises 8 inches to the foot (third pitch), under 8 on the first line is the
figure 14.42, this is the length of the common rafter for one foot run; if the building
is 16 feet wide, half the width of the building would be the run of the common
rafter; in this case it would be 8; multiply 14.42 x 8 = 115.36.
The total is 115.36 inches or 9 feet 7-3/8 inches. To obtain the bottom and
top cuts of the common rafters, use the figures 12 on the body and 8 on the
tongue; The 12 side will give the bottom cut and the 8 side will give the top cut;
the same figures will give the bottom and top cuts for the jack rafters.
On the second line under 8 is the figure 18.76. Multiply this figure by 8, this is the
run of the common rafter 18.76 x 8=150.08.
The total is 150.08 inches or 12 feet 6 inches. This is the correct length of the hip
or valley rafter. To obtain the bottom and top cuts of the hip or valley rafter, use
the figures 17 on the body and rise per foot run on the tongue; The 17 side will
give the bottom cut; the figure on the tongue will give side and top cut.
The reason for giving the lengths for one foot of common and hip or valley rafters
is that it will work in all cases regardless of width of buildings.
On the third line under 8 is the figure 19.23 inches; this is the length of the first
jack rafter, also the difference in the length of the others spaced 16 inches on
centers. For example, the first jack rafter being 19.23 inches, the second jack
rafter would be 3 feet 2-1/2 inches; making each one 19.23 inches longer than
the other.
Page size 100 mm x 140 mm FOLDS to 100 mm x 35 mm
Model No. 80008 On the fourth line under 8 is the figure 28.84 inches this is the length of the first
jack rafter and the difference in the length of the others spaced at 24 inches
QUESTION...
on center.
In marking angle cuts, particularly for the fifth or sixth lines on the tables, the 12
1•847•780•6120
inch mark is always used for top, bottom and side angle cuts.
The side cuts are always on the right hand or tongue side on rafters. When
marking boards these can be used for convenience at any time by taking the 12
inch mark on the body and using the body references on the tongue.
On the fifth line under 8 is the figure 10. By placing the square on stock to be cut
at figures 10 on body and 12 on tongue, and marking on 12 side, this gives side
cut of jacks against hip or valley rafters.
On the sixth line the figures refer to the graduation marks on the outside of
the body.
These figures on the square have been derived by deciding the figures to be used
with 12 on the tongue for the side cuts of the various pitches by the following
method:
NOTE:
• To obtain the lengths and cuts be careful to use the figures under whatever
figure your roof raises to the foot; if your roof raises to 12 inches to the foot,
or half pitch, look under 12 and so on in all cases. In cutting jack rafters, allow
for half the thickness of hip or valley rafters as lengths given on square are to
center lines.
• The figures on the square giving side cuts of jacks will also give the correct
miter cuts for mouldings in the valley at the junction of two gables and miter
cuts for gable mouldings where it intersects with level mouldings at the end of
a building.
• The figure giving cuts of sheathing in the valley or hip also give cuts for mitering
level plancier with gable plancier; also the miter cuts where two gable planciers
intersect; also the cut for plancier on gable end.
• To locate the bottom and top cuts of hip or valley rafter, use the figures 17
on body and whatever figure your roof raises to the foot, this will give you the
correct cuts in all cases.
To locate the bottom and top cuts of common rafters and jack rafters, use the
figures 12 on the body and whatever figure your roof raises to the foot on the
tongue; this gives the correct cuts in all cases. Always remember that the cuts
come on the tongue, or last named figure; it is so arranged in all cases.
From a plum line, the thickness of the rafter is measured and marked at
the right angles. A line is then squared across the top of the rafter and the
diagonal points connected. This line or side cut is obtained by marking
along the tongue of the square.