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SHEET METAL DRAFTING
Big End of an Elbow.—The big end is the piece that starts at the base line. Its "cut" is equal to the diameter of the elbow×π, plus the necessary allowance for locks or laps. The big end cut of a 7-inch elbow would be (7×π)+1=22.991 in. (or 23 in.)
Figs. 76–78—Two-piece Elbow.
Small End of an Elbow.—The small end is the last piece of an elbow. Its "cut" is found by subtracting seven times the thickness of the metal used from the big end cut. Thus the small end
