A wrench is a spanner having two or more handles, and usually consists of a straight tool having a thicker portion in the middle, in which is a square hole, or in some spanners, two or three holes of different sizes ; these holes are made to fit the heads of taps and broaches, and are used when the work to be operated upon is held by a vice. Wrenches are represented by Figs. 358, 361, 362, and 364. If a wrench is only about two feet in length, it is used by only one man, but long wrenches, for tapping large nuts when they cannot be conveniently tapped in a machine, are used with three or four men, each wrench having three or four handles. A tap spanner for small work is denoted by Fig. 358, having but one hole; and another one, having three holes of different sizes, is shown by Fig. 362. In some cases, taps and broaches are employed in holes which are in corners, or near walls, while in such places the taps are rotated by a spanner having only one handle ; a tool of this form is indicated by Fig. 361. A large capstan spanner for tapping large nuts is shown by Fig. 364 ; this is employed for large nuts that are fixed in a vice or other grip of suitable dimensions which is conveniently situated to allow the long handles of the spanner to revolve. A spanner of this class may be used also for rotating the boring bar of a portable boring machine.

Any hole in any tap spanner may be adapted to the head of a tap or broach, although the head may be too small for the hole, and the adaptation consists in either putting a garnisher into the hole, or placing one on to the tap-head. The garnisher consists of a piece of iron or steel which fits the space between the sides of the tap-head and the sides of the hole in the wrench, and is shown by Fig. 359. This garnisher, or filler, is made by bending a piece of metal which is only as thick as the space around the tap-head.when it is in the wrench-hole ; consequently, if the hole in the wrench is seven-eighths square, and the tap-head only three-quarters of an inch square, the piece for the intended filler is a sixteenth thick. After such a piece is cut to length and heated, it is angled by laying it across a hollow, and hammering a piece of square iron into the work, the piece of iron which is used being equal in thickness to that of the tap-head. After the filler is formed, it is put into its hole, and riveted a little at each end, to prevent its falling out; and while in its place it is filed until the head of the tap will slip easily into and out of the hole, at which time the tool is ready for use.