Elbows In Four Sections

Fig. 67. To describe a Pattern for an Elbow in Four Sections.

Let ABED, fig. 67, be the given elbow; draw the line FC; make FM equal in length to one-half the diameter of the elbow, with F as a centre; describe the arc KL; divide the arc KL into three equal parts; draw the lines FH and FI; also the line IH divide the section HK into two equal parts, and draw the line FG; draw the line AB at right angles to BC; describe the semicircle ANB; divide the semicircle into any number of equal parts, from the points draw lines parallel to BC, as 1, 2, 8, etc.

Fig. 68.

Set off the line ABC, fig. 68, equal in length to the circumference of elbow AB; erect the lines AF, BD and CE; set off on each side of the line BD the same number of equal distances as in the semicircle ANB; from the points draw lines parallel to BD as 1, 1, 2, 2, etc.; make BD equal to BG; make AF and CE equal to AJ; also, each of the parallel lines, bearing the same number as 1, 1, 2, 2, 3, 3, etc.; then a line traced through the points will form the first section; make FG and EJ equal to HI; reverse section No. 1; place E at G and F at J; trace a line from G to J; make GH and JI equal to PO, fig. 67, or to DK, fig, 68; take Sec. No. 1, place F at H and E at I, and trace a line from H to I, this forms Sec. No. 3 and 4.

Edges to be allowed.

Elbows.

Fig. 69. To describe a Pattern for an Elbow in Five Sections.

Let ABED, fig. 69, be the given elbow; draw the line FC; make FL equal in length to one-half the diameter of the elbow, with F as a centre; describe the arc GM; divide the arc GM into four equal parts, and draw the lines FJ and FH; also, the line IH; divide the section GH into two equal parts, and draw the line FK; draw the line AB at right angle to BC; describe the semicircle ANB; divide the semicircle into any number of equal parts; from the points draw lines parallel to BC, as 1, 2, 3, etc.

Fig. 70.

Set off the line ABC, fig. TO, equal in length to the circumference of the elbow AB; erect the perpendicular lines AL, BD and CK; set off on each side of BD the same number of equal distances as in the semicircle ANB; from the points draw lines parallel to BD as 1,1, 2,2, etc.; make BD equal to BK; make AF and CE equal to AO; also, each of the parallel lines bearing the same number, as 1,1, 2,2, 3,3 etc.; then a line traced through the points will form Sec. 1; make FG and EH equal to HI; reverse Sec. 1, place E at G and F at H, and trace a line from G to H; make GJ and HI equal DM in fig. 70; take Sec. 1 and place E at I and F at J, and trace a line from J to I; make JL and IK equal to HI; reverse Sec. 1, and place E at L and F at K, and trace a line from L to K, this completes Sec. No. 4 and 5; this completes the patterns; when elbows are to be of heavy iron and riveted, punch the holes for the rivets on the lines FE, GH, JI and LK, allowing for the lap each side on sections No. 2, 3, and 4.

Elbows.