Laying out for boiler makers and sheet metal workers; a practical treatise on the layout of boilers, stacks, tanks, pipes, elbows, and miscellaneous sheet metal work . oining these points with 0. We nowhave the true lengths of all the solid and dotted lines andare ready to proceed with the actual expansion. In Fig. 3 lay out the horizontal line 0-0 equal in length tothe full line O-o in Fig. 2. Set a pair of dividers to the spac-ing o-i, i-2, etc., on the small semi-circle and set anotherpair of dividers to suit the spacing of the large semi-circle. The setting of these dividers should be very
Laying out for boiler makers and sheet metal workers; a practical treatise on the layout of boilers, stacks, tanks, pipes, elbows, and miscellaneous sheet metal work . oining these points with 0. We nowhave the true lengths of all the solid and dotted lines andare ready to proceed with the actual expansion. In Fig. 3 lay out the horizontal line 0-0 equal in length tothe full line O-o in Fig. 2. Set a pair of dividers to the spac-ing o-i, i-2, etc., on the small semi-circle and set anotherpair of dividers to suit the spacing of the large semi-circle. The setting of these dividers should be very carefully doneas any little inaccuracy here will throw the whole work , with o as a center, with the dividers set to the large spac-ing, strike an arc. With 0 as a center, and the distance 2, as a radius, strike an arc cutting the previous arc at I as a center, and the distance o-i, Fig. 2, as a radius,strike an arc. Now, with o as a center, with the dividers setto the small spacing, strike an arc cutting the previous arc ati. Continue this operation until the points 8 and 8 arereached. Join the points 0, i, 2, 3, 4, 5. 6, 7 and 8 with a. FIG. 3. smooth curve, and similarly with the points 0, i, 2, 3, 4,.S, 6, 7 and 8. This then is the true expansion of half ofthe truncated cone shown in Fig. 2. The above illustrates in a simple manner the method of de-veloping irregular surfaces by triangulation. It will be readilyseen that it is not an absolutely accurate method of layingout, due to the fact that a curved surface is divided into asmall number of parts and these parts are assumed to bestraight lines. However, with a sufficient sub-division andwith great care on the part of the layerout, no great inac-curacy will result. It is not advisable to lay out surfaces bytriangulation, except as a source of last resort, that is, ifthere is any other feasible method for expanding the article,use it. However, there are a great many irregular-shapedforms that can on
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Keywords: ., bookcentury1900, bookdecade1900, bookidl, booksubjectsteamboilers
