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Ab Cd

line, shown, draw, fig, plan, lines, true and profile

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AB CD show the elevation of the corner on which a gore piece is re quired. H 7' E in plan is a section through C D, and E F G H is a section through X I, all projected from the elevation as shown. The profile 1 7 can be drawn at pleasure, and at once becomes the pattern for the sides. Now divide the profile 1 7 into an equal number of spaces as shown, from which drop vertical lines onto the side 7' E in plan, as shown from 1' to 7'. From these points draw lines parallel to F G, intersecting the opposite side and crossing the line 7' 1" (which is drawn at right angles to F G from 7') at 1" 2" 3" 4" 5" 6". Draw any line parallel to C D, as K J, upon which place all the intersections contained on 7' 1" in plan, as shown by 1° to 7° on K J. From these points erect perpendicular lines, which intersect by lines drawn from larly numbered points in elevation parallel to C D. Through the points thus obtained trace a line. Then will 1° to 7° be the true profile on 7' 1" in plan.

For the pattern for the gore, draw any vertical line, as A B in 323, upon which place the stretchout of the profile 1° 7° in Fig. 322, as shown by similar figures on A B in Fig. 323. At right angles to AB, and through the figures, draw lines as shown, Now, measuring in each instance from the line 7' 1" in plan in Fig. 322, take the various distances to points 1' to 7', and place them in Fig. 323 on similarly numbered lines, measuring in each instance from the line A B, thus locating the points shown. Trace a line through the points thus obtained. Then will F G 7 be the pattern for the gore shown in plan in Fig. 322 by F G 7'.

In Fig. 324 is shown a face view of a six-pointed star, which often arises in cornice work. No matter how many points the star has, the principles which are explained for its development are applicable to any size or shape. Triangulation is employed in this problem, as shown in Fig. 325. First draw the half-outline of the star, as shown by A B C D E F G. Above and parallel to the line AG, draw JH of similar length, as shown. Draw the Qection of the star on A G in plan, as shown by J K H. Project K into plan as shown at I, and draw the miter-lines B I, C I, D I, E I, and F I. As K H is the true length on I G, it is necessary that we find the true length on I F. Using I F as radius and I as center, draw an arc intersecting I G at a. From a erect a line cutting J H in section at b.

Draw a line from b to K, which is the true length on I F.

For the p a t t e r n, proceed as shown in Fig. 326. Draw any line, as K H, equal in length to K H in Fig.

325. Then, using K b as radius and K in Fig. 326 as center, describe the arc b b, which intersect at a and a by an arc G G struck from 11 as center and with F G in plan in Fig. 325 as radius. Draw lines in Fig. 326 from K to a to H to a to K, which will be the pattern for one of the points of the star of which 6 are required.

When bending the points on the line HK, it is necessary to have a stay or profile so that we may know at what angle the bend should be made. To obtain this stay, erect from the corner B in Fig. 325 a line intersecting the base-line J 11 at c, from which point, at right angles to J K, draw c d. Using c as center, and c d as radius, strike an are inter secting J H at e. From e drop a vertical line meeting A G in plan at d'. Set off i B' equal to i B, and draw a line from B to d' to which is the true profile after which the pattern in Fig. 326 is to be bent. If the stay in Fig. 325 has been cor rectly developed, then d' B' or d' B must equal e a in Fig. 326 on both sides.

In Fig. 327 is shown a finished elevation of a hipped roof, on the four corners of which a hip ridge A A butts against the upper base B and cuts off on a vertical line at the bottom, as C and C. To obtain the true profile of this hip ridge, together with the top and lower cuts and the patterns for the lower heads, proceed as shown in Fig. 328, where the front elevation has been omitted, this not being necessary, as only the part plan and diagonal elevation are required. First draw the part plan as shown by A B C D E F A, placing the hip or diagonal line F C in a horizontal position; and make the distances between the lines F A and C B and between F E and C D equal, because the roof in this case has equal pitch all around. (The same principles, how ever, would be used if the roofs had unequal pitches.) Above the plan, draw the line G H. From the points F and C in plan, erect the lines F G and C I, extending C I to Cl so that I will be the re quired height of the roof above G I at the point C in plan. Draw a line from G to C', and from Cl draw a horizontal and vertical line indefinitely, as shown. Then will I G Cl be a true section on the line of the roof on F C in plan.

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