MATERIALS AND WORKMANSHIP 53 



and parallel to each other, unless otherwise called for. The 

 boring shall be done after the member is riveted up. 



227. Variation in Pin Holes. The distance center to center 

 of pin holes shall be correct within ^ in. and the diameter of 

 the holes not more than -^ in. larger than that of the pin ; for 

 pins up to 5 in. diameter, and ^ in. for larger pins. 



228. Pins and Rollers. Pins and rollers shall be acurately 

 turned to gauges and shal be straight and smooth and entirely 

 free from flaws. 



229. Pilot Nuts. Pilot and driving nuts shall be furnished 

 for each size of pin in such numbers as may be ordered. 



230. 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 inch. 



231. Bed Plates. Expansion bed plates and vertical webs 

 of pedestals shall be planed true and smooth. Cast wall or 

 bed plates shall be planed top and bottom. The finishing cut of 

 the planing tool shall be fine and correspond with the direction 

 of expansion. 



232. Annealing. Steel, except in minor details, which has 

 been partially heated shall be properly annealed. (Par. 233.) 



233. Steel Castings. Steel castings shall be free from large 

 or injurious blowholes and shall be annealed. 



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



235. Shipping Details. Pins, nuts, bolts, rivets, and other 

 small details shall be boxed or crated. 



236. Weight. The scale weight of every piece and box 

 shall be marked on it in plain figures. 



237. Finished Weight. Payment for pound price contracts 

 shall be by scale weight. No allowance over 2 per cent of the 

 total weight of the structure, as computed from the plans, will 

 be made for excess weight. 



