This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
Note the difference in the shapes and spaces between these two modified profiles and the given profile A. It will be noticed that a portion of the gable moulding miters on the horizontal moulding G H from 6x to 10'.
For the pattern for the gable moulding, proceed as follows: At right angles to E F, draw the stretchout line J K, upon which place the stretchout of the given profile A, as shown by the figures 1 to 10 on J K. Through these figures, at right angles to J K, draw lines as shown, which intersect with lines drawn at right angles to E F from similarly numbered intersections in 1o 10o at the top and 1x 6x 10' at the lower end. Trace a line through the intersections thus obtained. Then will L M N BO be the pattern for C.
For the pattern for the horizontal return at the top, draw a side view as shown at B, making P R the desired projection, and the profile 1 19 on B, with its various intersections, an exact reproduction of 1o 10o in the elevation. Extend the line R T as R S; and, starting from 10, lay off the stretchout of the profile in B as shown by the figures 1 to 10 on R S, being careful to measure each space separately. At right angles to R S draw the usual measuring lines, which intersect by lines drawn parallel to SR from similarly numbered points in the profile in B. Trace a line through points thus obtained. Then will U V 10 1 be the pattern for the return B.
In similar manner, draw the side view of the lower horizontal return as shown at D, making the projection W 10 equal to P R in B. The profile shown from 1 to 10 in D, with all its divisions, is to be an exact reproduction of the profile lx to 10x in elevation. Extend the line W X as X Y, upon which lay off the stretchout of the profile 1 10 in D, being careful that each space is measured separately, as they are all unequal. Through the figures on X Y draw lines as shown, which intersect by lines drawn parallel to W Y from the various intersections in the profile in the side D. A line traced through points thus obtained, as shown by Z V, will be the desired cut, and 1 Z V 10 the pattern for the return D.
In Fig. 304 is shown a front view of a segmental pediment with upper and lower horizontal returns. This presents a problem of obtaining the pattern for horizontal returns at top and foot of a segmental pediment, shown respectively at A and B, the given profile to be placed in C. The principles used in obtaining these patterns are similar to those in the preceding problem, the only difference being that the moulding is curved in elevation. In Fig. 305 the true method is clearly given. First draw the center line B D through which draw the horizontal line C C1. From the line C C1 establish the height E; and with the desired center, as B, draw the arc E C intersecting the line C1 C at C.
In its proper position on a vertical line F G, parallel to D B, draw the given profile of the curved moulding as shown by A. which divide into equal spaces as shown from 1to 10. Through these figures, at right angles to F G, draw lines intersecting the center line D B as shown.
Then, using B as center, with radii of various lengths corresponding to the various distances obtained from A, describe arcs as shown, extending them indefinitely below the foot of the pediment. The point C or 6" being established, take a tracing of the profile A, with all the various points of intersection in same, and place it as shown by A2, being careful to have the point 6 in A2 come directly below the point 6" in elevation in a vertical position. Then, from the various intersections in A2 erect vertical lines intersecting similarly numbered arcs drawn from the profile A. Trace a line as shown from 1" to 10", which is the modified profile for the foot of the curved moulding.
Establish at pleasure the point 1' at the top, and take a tracing of the given profile A, placing it in a vertical position below 1', as shown by A1. From the various intersections in A1 erect vertical lines intersecting similarly numbered arcs as before. Through these intersections, shown from 1' to 10', trace the profile shown, which is the modified profile for the top return.
The curved moulding shown in elevation can be made either by hand or by machine. The general method of obtaining the blank or pattern for the curved moulding is to average a line through the extreme points of the profile A, as I J, extending it until it intersects a line drawn at right angles to D B from the center B, as B H, at K.
We will not go into any further demonstration about this curved work, as the matter will be taken up at its proper time later on.
To obtain the pattern for the upper and lower return mouldings, proceed in precisely the same manner as explained in connection with returns B and D in Fig. 303.
In Fig. 300 are shown the plan and elevation of a gable moulding in octagon plan. This problem should be carefully followed, as it presents an interesting study in projections; and the principles used in solving this are also applicable to other problems, no matter what angle or pitch the gable has. By referring to the plan, it will be seen that the moulding has an octagon angle in plan a b c, while similar points in elevation a' b' c' run on a rake in one line, the top and foot of the moulding butting against the brick piers B and A.
The method of proceeding with work of this kind is explained in detail in Fig. 307, where the principles are thoroughly explained. Let A B C D E represent a plan view of the wall, over which a gable moulding is to be placed, as shown by G H I J, the given profile of the moulding being shown by L M. Divide the profile into equal spaces as shown by the figures l to 8. Parallel to I H or J G, and through the figures mentioned, draw lines indefinitely as shown. Bisect the angle B C D in plan, and obtain the miter-line as follows: With C as center, and any radius, describe the arc N O. With N and O as centers, and any radius greater than C N or C O, describe arcs intersecting each other at P. From the point C, and through the intersection P, draw the miter-line CQ. Transfer the profile L M in elevation to the position shown by R S in plan, dividing it into the same number of spaces as L M. Through the figures in the profile R S, and parallel to D C, draw lines intersecting the miter-line C Q, as shown. From the intersections on the miter-line, and parallel to C B, draw lines intersecting the surface B A. Now, at right angles to C D in plan, and from the intersections on the miter-line C Q, draw vertical lines upward, intersecting lines of similar numbers drawn from points in profile L M in elevation parallel to J G. A line traced through points thus obtained, as shown from 1' to 8', will be the miter-line in elevation.