PREFACE THE importance of a quick and accurate method of securing patterns for elbows, has induced the writer to lay before the Sheet Metal Worker in the following pages, methods which may be employed in securing the patterns for elbows of any angle or number of pieces in all forms of pipe. Methods are here pointed out which admit of the least display, and the greatest accuracy, without that study of geometrical work usually recommended. In other words, if we possess a pair of compasses and straightedge, we can produce patterns for elbows in round pipe of any size, angle, or number of pieces. With very little additional attention, we are enabled to produce the patterns for elbows of all forms of pipe with the greatest accuracy and in the least possible time, which is an important factor in these days of sharp competition. F. S. K. iii ELBOW PATTERNS PART I AN ANALYSIS OF THE FORMS INVOLVED IN PRODUCING THE PATTERNS FOR ELBOWS IN ROUND PIPE FIG. I illustrates a four pieced 90 degree elbow, and upon reducing this to its simplest form, we find it contains three elbows at an angle of 30 degrees. When it is stated that it contains three elbows at an angle of 30 degrees, it should be remembered that the term 30 degrees is to an extent shop phraseology, since angles are measured by the position the two lines of which they are formed occupy as radii of a circle. This places what is usually termed 30 degrees at 150 degrees, unless the axis of one arm of said angle or elbow is presumed to be parallel to a right line in space, then will the axis of the second arm be at an angle of 30 degrees to said right line. The writer has in this work, FOR ALL FORMS OF PIPE A TREATISE UPON THE ELBOW WITH USEFUL MATHEMATICAL RULES SECOND EDITION, ENLARGED BY F. S. KIDDER PUBLISHED BY THE SHEET METAL PUBLICATION CO. TRIBUNE BUILDING, NEW YORK |