Fig. 31 indicates a rod having an inside screw, which is occasionally used to connect the upper end, or what is sometimes the outer end, of a slide-rod. Six or eight sides are formed upon the boss for the convenience of rotating the rod with a spanner. It is not necessary to forge any opening or orifice whatever in the rod, because drilling or boring such small holes is a preferable process. It is generally most convenient to forge such rods of one piece, which is welded and made solid with hammering, to produce the larger boss in which a screw is to be made. The intermediate portion is next reduced by fullers and hammering, and a lump is allowed to remain for the smaller boss, in which is placed the joint-pin. Rods of this character must be welded to a proper distance from the outside; if not, the screw will be unsolid and liable to break.

Rods with inside screws are also used, which are of great length. In such cases, the larger boss is forged with a short stem only, which is afterwards welded to the intermediate portion of the rod that is of a suitable diameter to avoid reducing. Another smaller boss, or sometimes a joint-piece, is also made, and welded to the intermediate piece to complete the rod.