While the consulting bridge engineers of America do not yet agree entirely with the engineers of the bridge manufacturing companies concerning all points of design, the ideas of both have of late been gradually getting closer together. The differences of opinion are generally in the line of economics, the shopmen desiring to cheapen work in ways of which the consulting engineers disapprove.

Designs should be made so as to afford the bridge shops every facility possible for using their machinery to advantage. For instance, details should be arranged for multiple-punch spacing, and to suit the requirements for bending, machining, and the various other operations which are governed by the shop equipment.

One great bone of contention in times past was the matter of sub-punching and reaming as against punching full-size and running a loose reamer through the holes in the assembled component parts, so as to ensure the possibility of the passage of the hot rivets. Even today much work is done by the latter method, but it is generally confined to parts of so-called minor importance. The object of sub-punching and reaming is two-fold: first, to make the holes in the component parts match properly after the passage through them of rigid-drill reamers, and, second, to cut away the metal around the peripheries of the holes which was injured by the brutal process of punching. The author, if he could always have his way in this matter, would bar entirely the punching of holes full-size; and he believes the day is coming when even the sub-punching and reaming will be prohibited by adopting the method of solid drilling. He has asked some of the prominent bridge manufacturers how much extra it would cost to employ the latter method, and has been told that, if the shops were properly outfitted for the work, the excess cost as compared with sub-punching and reaming would be practically nil. For nickel steel and other high-alloy steels solid drilling should be exclusively employed.

In the case of sheared edges, if the metal near the shear is to be depended on for strength, the said edges should be planed, but otherwise the planing should be omitted, unless the raw edges would be too much in evidence to the beholder of the finished structure. It is more than probable that the shearing of edges is just as destructive as the punching; for the brutality of the treatment of the metal in the two cases is of the same character and apparently of the same severity.

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