410 



STRUCTURAL DRAFTING. 



CHAP. XII. 



number as on this side, but prefixed by the letter, S, instead of the letter, N." Mark trusses 

 T.I; T.2; etc. Mark purlins R.I; R.2; etc. 



The above scheme will necessarily have to be modified more or less according to circum- 

 stances; for example, where a building has different sections or divisions applying on the same order 

 number, in which case each section or division should have a distinguishing letter which should 

 prefix the mark of every piece. In such cases it will perhaps be well to omit other letters, such as 

 N., S., etc., so that the mark will not be too long for easy marking on the piece. In general, 

 however, the scheme should be followed of marking all the larger pieces, whether alike or not, 

 with a different mark. This would refer to pieces which are liable to be hauled immediately to 

 their places from the cars. But for all smaller pieces which are alike, give the same mark. 



DETAIL NOTES. Sections. End views of sections shall be shown as in (a) Fig. 19, and 

 sections shall be cross-hatched or blackened as shown in (b) Fig. 19. 



Assembling Note. Covers, webs, flange angles, etc., must not be marked alike when it 

 would be necessary to turn them end for end, see (c) Fig. 19. 



Rivet Spacing. Rivet spacing must be tied up from end to end. 



(a) 



j'Sf 



(c) 



. 

 /f 



(e) 



FIG. 19. 



Connection Plates. In detailing connection plates wherever bevel for holes on lines "b," 

 (d) and (e) Fig. 19, is different, spacing for holes on lines "a" should be made different to prevent 

 plates from being interchanged. 



Writing Angles. In writing angles give the longer leg first, l-L 6" X 4" X \" X io'-o|". 



Writing Plates. In writing plates the width of the plate is given in inches, the thickness in 

 inches, and the length in ft. and in.; 2-P1. 48" X f" X is'-of". A length of 9 in. should be 

 written o'-g" and not 9". The width of a plate is the dimension at right angles to the length 

 of the member, while the length of a plate is the dimension parallel to the length of the member 

 to which the plate is attached; except that for lacing bars, tie plates and other universal mill 

 plates 6 inches and less in width the least dimension is taken as the width of the member, and 

 for splice plates the width is the dimension at right angles to the splice. 



Writing Sections. Sections are written as follows: i-I 12" @ 40 Ib. X l6'-3l". 



Miscellaneous. Bevels may be shown as so many inches in 12", (a) Fig. 20; or where con- 

 venient the total lengths may be given as in (b) Fig. 20. The latter method is the better as it 

 assists the checker and the templet maker. 



The maximum amount that one leg of an angle can be bent is 45. For a greater bend than 

 45 a bent plate shall be used, (c) Fig. 20. 



The center to center length of stiff laterals should be -not less than rs in. short. 



Do not use 2 sizes of rivets in the same leg, or same angle, or same piece unless absolutely 

 necessary. 



