PUNCHING AND REAMING.

All rivet-holes in steel-work, if punched, shall be made with a punch one-eighth (1/8) inch in diameter less than the diameter of the rivet intended to be used, and shall be reamed to a diameter one-sixteenth (1/16) inch greater than that of the said rivet.

Before this reaming takes place all the pieces to be riveted together shall be assembled and bolted into position, then the reaming shall be done; for one of the principal objects of this clause in relation to subpunching is to ensure the correct matching of rivet-holes, and the avoidance of holes of excessive diameter. Said clause also ensures the removal of most, if not all, incipient cracks started by the process of punching.

All reaming is to be done by means of twist-drills, the use of tapered reamers being prohibited, except where twist-reamers cannot be employed. All holes must be at right angles to surface of member, and all sharp or raised edges of holes under heads must be slightly rounded off before the rivets are driven.

All holes for field-rivets, excepting those for lateral and sway-bracing, when not drilled to an iron template, shall be reamed while the connecting parts are temporarily assembled.

Punching shall not be permitted in any piece in which the thickness of the metal exceeds the diameter of the cold rivet that is to be used; but all such pieces shall be drilled solid.

BUILT MEMBERS.

Built members must, when finished, be true and free from twists, kinks, buckles, or open joints between the component pieces.

All abutting surfaces of compression-members must be planed or turned to even bearings so that they shall be in as perfect contact throughout as can be obtained by such means; and all such finished surfaces must be protected by white lead and tallow before shipment from the shop.

The ends of all webs and chord or flange angles that abut