Fig. 623 shows a _nipple-holder_ which is used to hold short pieces of pipe by the thread upon one end, while the die is applied to cut a thread upon the other end. This tool is generally used in a pipe cutting machine, which is operated by power, but it can also be held in a common vise.
NOTE.—The die may be centered on the nipple described above by _placing in the die stock_ a guide bushing that will easily ride over the nipple holder. The thread can now be cut until the die just touches the nipple holder, and there will be practically no blank space between the threads on the ends. After the die has been backed off the nipple can be removed from the holder by unscrewing the center with a monkey wrench. _A nipple holder should be made for each size of pipe that is cut and threaded by hand._ A piece of pipe with a coupling on its end may be used as an improvised nipple holder.
Fig. 624 shows an extension _pipe tongs_; this tool may be adjusted to fit a number of different sizes by manipulating the thumb screw, shown in the cut.
Fig. 625 represents the _Trimo pipe wrench_. This name is an abbreviation of the word Tremont from the street in Boston of that name. It is adjusted to its work by a milled nut in the pivoted jaw; the latter is brought into position at each stroke by a leaf spring attached to the main lever. In the larger sizes the steel jaws are removable or can be detached and replaced after being repaired. The lower engraving, Fig. 626, is a _chain tongs_ with removable, tool-steel jaws. The hard scale on the piping rapidly destroys the sharp edges on these jaws so that they require frequent sharpening. The links of the chain have a peculiar hook form so that they cannot slip.
_A spanner_, shown in Fig. 627, is a special form of wrench, which circles or spans around; generally used for twisting a circular-shaped portion, provided with holes in its circumference.
_Screw or monkey-wrenches_ are those which have a movable jaw, so that the tool may be adjusted to fit any sized nut within its compass; as shown in Fig. 628. There are many designs of monkey-wrenches. The one here represented is known as the “knife-handle” on account of the identical construction of the handle of this wrench and that of a pocket knife. It is strong and the shank is extra heavy so that it is hardly possible to spring the jaws in fair use.