The wheels here treated are those that possess arms with which the bosses or naves are joined to their respective rims, whether they are spur-teeth wheels, bevel-wheels, or other teeth-wheels; or whether they are fly-wheels, hand-wheels, and others with plain rims which may require to be rough as when cast, or to be smoothly turned in lathes.

Disc-wheels also are here noticed; these resemble circular discs having bosses in the middles and teeth on the rims. Such are also termed plate-wheels, through resembling plates of metal, and being destitute of arms or spokes.

A small wheel only a few inches in diameter, is held to the lathe-chuck with two or three plates and bolts. These are fixed so that the bolts, and the greater portions of the plates, are outside of the wheel's rim, the paws of the plates being on the rim. No other fastenings are required for a small wheel; and this mode of fixing is suitable whether the article has spokes, or is without, supposing that it is to be only bored, while fixed in this condition.

While adjusting a wheel to be bored on a lathe-chuck, two relative positions are to be considered; and with due regard to these, almost any wheel, small or large, may be properly fixed. The first of these positions is obtained when the wheel rim is placed parallel with the face of the chuck, which is usually effected by fastening the rim in direct contact with a few parallel blocks situate on the chuck. The second position is obtained as soon as the rim is placed concentric with the rim of the chuck, and therefore concentric with the lathe-spindle's motion. This position is secured after the rim is put into contact with the parallel blocks, and results from the wheel being gradually shifted to the exact place, either with hammering it, or moving it with poppet-screws.

In all wheels whose rims are not to be turned, the rims are the portions to be regarded during fixing, because they are cast to the specified dimensions, and therefore have no superfluous metal to be turned off. The bosses of such wheels are sometimes turned to make them true with the rims, and one end or face of each boss is also turned, to produce a surface at right-angles to the axis of the truly bored hole.

In consequence of the necessity for exactly adjusting the wheel's rim, it is requisite to first hold the wheel to the chuck without placing any holdfast plate upon the rim, because such would hinder the operator's observation during adjustment. A centre-bolt is therefore put through the boss-hole, and this, with a plate or washers in contact with the boss-face, will hold the wheel a short time until correctly placed. If the wheel-boss is without a hole, a couple of middle-plates or slot-plates may be put across the spokes; these plates have bolt-holes at about midway between the ends, so that when a plate is in position, its two ends are caused to bear upon two spokes, by means of a screw-bolt in the middle and extending through the space between the spokes to the chuck. While the wheel is held with a couple of these plates, its rim is quite free from all articles except the parallel blocks next the chuck, and these must be of sufficient thickness to keep the inner face of the wheel-boss far enough from the chuck to allow room for the tool-point, when advanced through the hole. The wheel rim can, therefore be now put true with the lathe spindle by gently hammering with a wood hammer or a tin hammer, while a pointer or other slide-rest tool is situated near the rim for adjusting.

As soon as adjustment is complete, the rim is seen to rotate truly while the lathe-spindle is rather quickly rotated ; and the wheel can now be finally fastened with the holdfast plates on the rim, which will not affect the adjustment, because the rim is in close contact with the blocks behind. Boring can, therefore, be next commenced, and the hole will be produced concentric with the rim, as required, although the outer surface of the boss may not be concentric with the hole, unless the wheel happened to have been truly formed at the time of casting.

In some cases, small wheels having arms are fixed for boring with regard to their arms. This is necessary when the rims are to be turned, in addition to turning or partly turning the bosses. A wheel to be thus treated is fixed to the chuck with parallel blocks in contact with the wheel arms, instead of in contact with the rim. This arrangement will cause the length of the hole when bored, to be square to the lengths of the arms, rather than square to the rim, unless the wheel happens to be truly cast, so that the rim is parallel with the arms. Wheel-arms are always cast to the specified shape and dimensions; therefore, nothing is to be removed from them, except by the ordinary trimming with filing. Consequently, it is requisite to bore the hole in such a wheel with regard to its arms, to avoid the risk of cutting deeply into one side of some one arm, at the time the rim is turned; whereas, if the arms are put parallel with the chuck, the subsequent turning of the rim will either equally reduce all the junctions of the arras, or not reduce them at all, according to the distance in the metal, to which the tool-point enters at the junctions.