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 . oint 8° with the second dividers strike off the arc 1°;;with a pair of dividers measure off the distance from the smallreference circle to the point 71. From the reference circlestrike off an arc locating a point I2. In a similar way strike offan arc from the large reference circle and determine the point1°:. These are two points of the developed surface. From I2strike another arc with the first pair of dividers, from i°2strike
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 . oint 8° with the second dividers strike off the arc 1°;;with a pair of dividers measure off the distance from the smallreference circle to the point 71. From the reference circlestrike off an arc locating a point I2. In a similar way strike offan arc from the large reference circle and determine the point1°:. These are two points of the developed surface. From I2strike another arc with the first pair of dividers, from i°2strike an arc with the second pair of dividers. Now transferthe distance from the reference circle to point 61, and thus de-termine the location of the points 2- and 2°=. These are twomore points of the developed surface. Continue this opera-tion until the points 82 and 8°2 are arrived at. If the construc-tion is properly made, the line and 8°2 if continued will passthrough the center C. This is a check on the construction, andif it does not come out right the work will have to be goneover again. Bend the steel straight edge, so as to take in these Fig-. 19 Fig. 20 straight edge. This should pass through C. We now checkup this construction to see that everything is correct. Strike a semi-circle on D and D, and divide each one ofthese half circles into any number, say eight, equal parts. Num-ber the points from zero to eight on the small circle and from0° to 8° on the large circle. Put the point of a pair of tramson the point zero, and strike an arc from i to 1. Similarlystrike an arc to points I, 2, 3, 4. etc., and in the same wayproject the points in the large circle on to the diameter D°.Number these points ii. 2i, 31, and i°i, 2°i, 3°i, etc. From zero, with the trams on the center C, strike the smallreference circle, open up the trams and strike the large refer-ence circle from the same center. Look up from a table ofcircumferences the half circumfe
Size: 2177px × 1148px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookidl, booksubjectsteamboilers
