66 STEEL ROOF TRUSSES AND MILL BUILDINGS. CHAP. I. 



160. Finish of Joints. Abutting joints shall be cut or dressed true and straight and fitted 

 close together, especially where open to view. In compression joints depending on contact 

 bearing the surfaces shall be truly faced, so as to have even bearings after they are riveted up 

 complete and when perfectly aligned. 



161. Field Connections. All holes for field rivets in splices in tension members carrying 

 live loads shall be accurately drilled to an iron templet or reamed while the connecting parts are 

 temporarily put together. 



162. Eye-Bars. Eye-bars shall be straight and true to size, and shall be free from twists, 

 folds in the neck or head, or any other defect. Heads shall be made by upsetting, rolling or forg- 

 ing. Welding will not be allowed. The form of heads will be determined by the dies in use at 

 the works where the eye-bars are made, if satisfactory to the engineer, but the manufacturer shall 

 guarantee the bars to break in the body with a silky fracture, when tested to rupture. The 

 thickness of head and neck shall not vary more than TJ- in. from the thickness of the bar. 



163. Boring Eye-Bars. Before boring, each eye-bar shall be properly annealed and carefully 

 straightened. Pin holes shall be in the center line of bars and in the center of heads. Bars of the 

 same length shall be bored so accurately that, when placed together, pins -^ in. smaller in diam- 

 eter than the pin holes can be passed through the holes at both ends of the bars at the same 

 time. 



164. Pin Holes. Pin holes shall be bored true to gage, smooth and straight; at right angles 

 to the axis of the member and parallel to each other, unless otherwise called for. Wherever pos- 

 sible, the boring shall be done after the member is riveted up. 



165. The distance center to center of pin holes shall be correct within -$ in., and the diameter 

 of the hole not more than -fa in. larger than that of the pin, for pins up to 5 in. diameter, and -% in. 

 for larger pins. 



1 66. Pins and Rollers. Pins and rollers shall be accurately turned to gage and shall be 

 straight and smooth and entirely free from flaws. 



167. Pilot Nuts and Field Rivets. At least one pilot and one driving nut shall be furnished 

 for each size of pin for each structure; and field rivets 15 per cent plus 10 rivets in excess of 

 the number of each size actually required. 



1 68. Screw Threads. Screw threads shall make tight fits in the nuts and shall be U. S. 

 standard, except above the diameter of if in., when they shall be made with six threads per in. 



169. Annealing. Steel, except in minor details, which has been partially heated shall be 

 properly annealed. 



170. Steel Castings. All steel castings shall be annealed. 



171. Welds. Welds in steel will not be allowed. 



172. Bed Plates. Expansion bed plates shall be planed true and smooth. Cast wall plates 

 shall be planed top and bottom. The cut of the planing tool shall correspond with the direction 

 of expansion. 



173. Shipping Details. Pins, nuts, bolts, rivets, and other small details shall be boxed or 

 crated. 



174. Weight. The weight of every piece and box shall be marked on it in plain figures. 



175. Finished Weight. Payment for pound price contracts shall be by scale weight. No 

 allowance over 2 per cent of the actual total weight of the structure as computed from the shop 

 plans will be allowed for excess weight. 



ADDITIONAL SPECIFICATIONS WHEN GENERAL REAMING AND PLANING ARE REQUIRED. 



176. Planing Edges. Sheared edges and ends shall be planed off at least J in. 



177. Reaming. Punched holes shall be made with a punch j^ in. smaller in diameter than 

 the nominal size of the rivets and shall be reamed to a finished diameter of not more than YS in- 

 larger than the rivet. 



178. Reaming after Assembling. Wherever practicable, reaming shall be done after the 

 pieces forming one built member have been assembled and firmly bolted together. If necessary 

 to take the pieces apart for shipping and handling, the respective pieces reamed together shall be 

 so marked that they may be reassembled in the same position in the final setting up. No inter- 

 change of reamed parts will be allowed. 



179. Removing Burrs. The burrs on all reamed holes shall be removed by a tool counter- 

 sinking about ik in. 



TIMBER. 



1 80. Timber. The timber shall be strictly first-class spruce, white pine, Douglas fir, Southern 

 yellow pine, or white oak timber; sawed true and out of wind, full size, free from wind shakes, 

 large or loose knots, decayed or sapwood, wormholes or other defects impairing its strength or 

 durability. 



