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STRUCTURAL DRAFTING. 

 STRUCTURAL DRAWINGS. 



CHAP. XII. 



METHODS. The drawings for structural steel work differ from the drawings for machinery 

 in that (a) two scales are used, one for the length of the member or the skeleton of the structure, 

 and one for the details; (b) members are commonly shown by one projection; and (c) the drawings 

 are not to exact scale, all distances being governed by figures. 



Two methods are used in making shop drawings. 



FIG. i. TRUSS JOINT, COMPLETELY DETAILED. 



(1) The first method is to make the drawings so complete that the templets can be made 

 for each individual piece on the bench. This method is used for all large trusses and members, 

 and where there is not room to lay the member out on the templet shop floor. The details for the 

 joint of a Fink roof truss completely detailed are shown in Fig. i. A joint of a roof truss of the 

 locomotive shop of the A. T. & S. F. Ry., at Topeka, Kansas, is completely detailed in Fig. 2. 



(2) The second method is to give on the drawings only sufficient dimensions to locate the 

 position of each member, the number of rivets, and the sizes of members, leaving the details to 

 be worked out by the templet maker on the laying-out floor. Sufficient data should be given 

 to definitely locate the main laying-out points. The interior pieces should be located by center 

 lines corresponding to the gage lines of the angles, or center line of the piece, as the case may be. 

 The rivet spacing should be given complete for members detailed on different sheets, or where 

 it is necessary to obtain a required clearance, and other places where it will materially assist the 



