. Canadian Shipping and Marine Engineering January-December 1916. d the principles involved in the development of cylin-drical and other forms, such as are met in sheet metal work, a considerable knowledge ofgeometry is desirable. Through the medium of these articles, the author places practicalexamples at the disposal of our readers, and the knowledge to be gained by a close and per-sistent study of the principles and methods employed will well repay the time spent. THE fabrication of elbows forms aconsiderable part of sheet ironworkers practice. The variousforms, cylindrical, oval and rectan
. Canadian Shipping and Marine Engineering January-December 1916. d the principles involved in the development of cylin-drical and other forms, such as are met in sheet metal work, a considerable knowledge ofgeometry is desirable. Through the medium of these articles, the author places practicalexamples at the disposal of our readers, and the knowledge to be gained by a close and per-sistent study of the principles and methods employed will well repay the time spent. THE fabrication of elbows forms aconsiderable part of sheet ironworkers practice. The variousforms, cylindrical, oval and rectangular,will be herewith described, and the pat-terns developed for both heavy and lightplate. For the purpose of students homepractice, the measurements will be given bered in relation to the points on thehalf plan view. As the elbow is made in two coursesand of equal diameters, it will readilybe seen that the mitre line as statedforms an angle of 45° degrees, thereforeit will only be necessary to lay out onecourse, from which afterwards the othermay be in inches, so that the developments maybe made on stiff paper. The patternsmay be perforated at the located rivetholes, by a punch similar to a tramconductors transfer punch, which maybe purchased at any 15-cent store, thispunches a round hole. The patterns canthen be connected together by commonpaper fasteners. This is good practicefor the student in laying out the rivetholes, which will give him the necessaryconfidence when laying out on the plate. Cylindrical Elbows Fig. 1 shows an ordinary two-piece 90-fleeTee elbow which will be developed bythe parallel line method. Measure off AF, Fig. 1, equal to iy2inches, at ri?ht angles to AF. draw ABand FE, making AB equal to 2% inches,and FE % inch. BC is drawn parallel toAF. and equal in length to AB. CD isparallel to BA, and equal in length toAF. DE is drawn at right angles to CDand EF, and of the same length as the mitre line BE. which is at45 degrees, to the l
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