Pentagon 11 " " 8 " Hexagon 4 " " 7 Heptagon 121 " " 6 " The miter is to be drawn along the line of the first column, as shown for the triangle in Fig. S, and for the hexagon in Fig. 9.
In Fig. 10 is shown a diagram for finding degrees on the square. For example, if a pitch of 35 degrees is re . quired, use Slg- on tongue and 12 on blade; if 45 degrees, use 12 on tongue and 12 on blade; etc.
In Fig. 11 is shown the relative length of run for a rafter and a hip, the rafter being 12 ineheS and the hip 17 inches. The reason, as shown in this diagram, why 17 is taken for the run of the hip, in stead of 12 as for the common rafter, is that the seats of the com mon rafter and hip do not run parallel with each other, but di verge in roofs of equal pitch at an angle of 45 degrees; therefore,17 inches taken on the run of the hip is equal to only 12 inches when taken on that of the common rafter, as shown by the dotted line from heel to heel of the two squares in Fig. 11.
In Fig. 12 is shown how other figures on the square may be found for corners that deviate from the 45 degrees. It is shown that for a pentagon, which makes a 36-degree angle with the plate, the figure to be used on the square for run is 14i inches; for a hexagon, which makes a 30-degree angle with the plate, the figure will be 13; inches; and for an octagon, which makes an angle of 221 de grees with the plate, the figure to use on the square for run of hip to corre spond to the run of the common rafters, will be 13 inches. It will be observed that the height in each case is 9 inches.
Fig. 13 illustrates a method of finding the relative height of a hip or valley per foot run to that of the common raf ter. The square is shown placed with 12 on blade and 9 on tongue for the common rafter; and shows that for the hip the rise is only inches.
The Steel Square as Applied in Roof Pram= ing. Roof framing at present is as simple as it possibly can be, so that any attempt at a new method would be super fluous. There may, however, be a certain way of presenting the sub ject that will carry with it almost the weight assigned to a new theory, making what is already simple still more simple.
The steel square is a mighty factor in roof framing, and without doubt the greatest tool in practical potency that ever was invented for the carpenter. With its use the lengths and bevels of every piece of timber that goes into the construction of the most intricate design of roof, can easily be obtained, and that with but very little knowledge of lines.
In roofs of equal pitch, as illustrated in Fig. 14, the steel square is all that is required if one properly understands how to handle it.
What is meant by a pi/eh of a roof, is the number of inches it rises to the foot of run.
In Fig. 15 is shown the steel square with figures representing the various pitches to the foot of run. For the -1-pitch roof, the figures as shown, from 12 on tongue to 12 on blade, are those to be used on the steel square for the common rafter; and for pitch, the figures to be used on the square will be 12 and 9, as shown.
To understand this figure, it is necessary only to keep in mind that the pitch of a roof is reckoned from the span. Since the run in each pitch as shown is 12 inches, the span is two times 12 inches, which equals 24 inches; hence, 12 on blade to represent the foot run, and 12 on tongue to represent the rise over the span, will be the figures on the square for a -pitch roof.
For the pitch, the figures are shown to be 12 on tongue and 9 on blade, 9 being * of the span, 24 inches.
The same rule applies to all the pitches. The pitch is shown to rise 4 inches to the foot of run, because 4 inches is -k of the span, 24 inches, the -A- pitch is shown to rise S inches to the foot of run, because S inches is 3 of the span, 24 inches; etc.
The roof referred to in Figs. 16 and 17 is to rise 9 inches to the foot of run; it is therefore a L-pitch roof. For all the common rafters, the fig ures to be used on the square will be 12 on blade to represent the run, and 9 on tongue to represent the rise to the foot of run; and for all the hips and valleys, 17 on blade to represent the run, and 9 on tongue to represent the rise of the roof to the foot of run.