Page:Sheet Metal Drafting.djvu/65

Rh cut of a 7-inch elbow made from No. 24 U. S. S. Gage would be 22.991-(.025&times;7)=22.991-.175=22.816 in. ($$\scriptstyle{22\frac{13}{16}}$$ in.)

Angle of an Elbow.—The angle of an elbow is a measure of the opening formed by two straight lines drawn from the center of the elbow to the extremities (ends) of the arc of the back.

Miter Lines of an Elbow.—The miter lines are the lines of junction between the pieces of the elbow. All miter lines must meet at the center of the elbow.

The student is required to make a drawing similar to Fig. 77 and to name all the parts defined above. The profile should be made about four inches in diameter but the size of the drawing is left to the student's discretion.