After nuts have been screwed by some means they are ready for facing. This operation consists in making the faces or broad sides of the nut plane and parallel with each other; and also square to the nut-screw, which is the same as being square to the length of the bolt. The facing of nuts is always executed by turning; and it is needful for at least the inner face of every nut to be turned that it may be caused to properly bear upon the surface of the object to be held. The opposite or outer face need not be turned except for appearance, unless the nut is too thick, or it is required to have a specified form.

The instruments required for nut-facing are screw-arbor chucks, and screw-arbors. A screw-arbor chuck is also termed, a nut-chuck, because it is employed for facing nuts while it is screwed tight on the lathe-spindle as other lathe-chucks. A screw-arbor is also termed a nut-arbor, being an arbor specially used for turning nuts. A nut-chuck consists of a short screw which projects from a chuck that rotates with the lathe-spindle, through being attached to any convenient disc-chuck which is on the spindle-end. The screw of the nut-chuck is so made as to be exactly true with the lathe-spindle axis; it is also rather taper and very short, being only long enough to tightly hold a nut when screwed thereon without allowing the screw's end to extend to the mouth of the hole in the nut. By referring to Fig. 948, a nut-chuck may be seen attached to a small disc-chuck in position on the spindle-end ; and in the comparative large Fig. 949, a nut is shown which is tightly screwed on a nut-chuck and ready for facing. It will be seen that this Figure shows the outer face of the nut wholly free from the chuck-screw within, and therefore capable of being easily turned without causing the turning-tool to touch any part of the chuck-screw. Each size of nuts requires a distinct chuck, because each nut must tightly fit the screw and remain without shifting while being turned ; and the chucks are named the same as the sizes of the nuts to be placed thereon.

A nut-arbor consists of a spindle having a taper screw near one end. The screw part is analogous to the screw of a nut-chuck, being made slightly taper, and to fit some special size of nuts, and rotate them while screwed tight thereon. But a nut-arbor is used by rotating it and the nut thereon while on the lathe-pivots; consequently, the arbor is of a convenient length, such as eleven or twelve inches, and should be furnished with large centre-recesses at its ends, to bear properly on the pivots.

The nut-arbor shown by Fig. 950, consists of a spindle having a shoulder or bearing for the nut, in addition to the screw. An arbor of this class has a parallel screw because it is not required to tightly fit the nut. Such an implement allows a nut to be quickly screwed along the screw to the shoulder, causing one of the nut's faces to come into contact and fix it ready for turning. Although nuts can be rapidly fixed and unfixed from such an arbor, it will be found that if the nut-face which touches the shoulder is not square with the nut-screw, the facing will not be effected square with the screw, as required.

One of the author's nut-arbors is shown by Fig. 951. This consists of a steel spindle having an end which is screwed and slightly taper, and also a comparative small cylindrical portion extending from the screw-part. The screw being taper, causes a nut to be held tight thereon without the need of coming into contact with any shoulder, consequently, none is provided. The diameter of the stem or small end is considerably less than that of the holes in the nuts to fit, because ample space should exist around the stem between its surface and the nut-thread, in order to allow the point of the cutting tool room to disengage from the metal that adjoins the hole. The opposite or handle-end of the spindle is that by which it is rotated in a lathe, this end being gripped with a distinct carrier unless the spindle is provided with a carrier as part of the instrument. This is the case with the one shown by the Figure (951) the end having a hole formed for holding a sort of lever consisting of a straight piece of iron or steel. A carrier of this class may be slightly bent after being put into the hole, to prevent it shifting while in use.

Only one face of a nut can be completely faced at one time on an arbor, whether it is on a nut-arbor or on a nut-chuck. It is therefore necessary to smoothly finish one face and take off the nut to place it again upon the arbor for turning the other face. At the reversal of the nut to have the second face turned, and after it is again screwed tight upon the arbor, the already turned face should rotate exactly true and right-angular to the spindle's axis of motion. But this is not always the case; and it is sometimes necessary to again take off nuts after they have been screwed tight upon the arbor, and clear out dirt or shavings that may hinder the nut-screws from properly fitting the screw of the arbor. Such hindrances will in some cases cause the nuts to rotate so much out of their proper directions as to render them after turning rather inferior to their condition before turning.

In some cases nuts are shamfered. Shamfering consists in bevelling the corners belonging to a face of a nut, some having both faces shamfered. The principal reason for shamfering, is to ornament one of the faces; consequently, the face to be outwards is the one to be shamfered. That which is termed the shamfer of a nut, is, therefore, the bevelled portion referred to, which usually includes a small portion of the face adjoining. In Fig. 946 the shamfer of a nut is shown, and it is usually formed by turning with a tool of proper angle, which is applied after the face is finished. The angle of a shamfer with the face of a nut, should be 45°, and the greater the shamfer of any nut, the smaller is the face that has the shamfer; consequently, it may be seen that the inner or gripping face of a nut should not be shamfered, because it diminishes the available bearing surface. One of the author's shamfer-guages is shown in contact with a nut in Fig. 947. The handle is of convenient size for holding; and the lower arm of the gauge is comparatively short, that it may not be much in the way when applying it to a nut which is on an arbor.

The stop-nut shown by Fig. 953, is of a class much used ; and the stem or cylindrical part of such a nut is the portion last turned. After the opposite face is finished the distance to the commencement of the stem can be shown, and the stem's length also shown ; the stem is therefore reduced to the proper size, and the superfluous length of metal is cut off the face adjoining the stem.

Shaping the six outer sides or planes of nuts, is the last paring-process to which they are subjected. This is effected either by planing or shaping, while a number of nuts are held together on an arbor, according to the instructions in page 230; or is effected by means of rotating cutters that rotate in the manner of a chuck belonging to a lathe.

Turning of Spindles, Rods, etc.