Twisting the axle is resorted to for placing the cranks into their proper positions. For small axles, this operation is conveniently performed at a bright yellow heat while the work is in a furnace or other fire. The portion of the axle heated is that between the two cranks. The first heat is given to that part which adjoins one of the cranks, and the length of axle heated should be about two feet, if the fire will permit. By heating a great length of axle, the twist will be equally distributed along the work; but, if the fire is not large enough for this purpose, a greater number of heatings and twistings should take place. The extent of twist first given may be about thirty degrees ; the adjoining portion of the axle is next heated, and the angular distance between the two cranks is increased with twisting to about sixty degrees; after which another portion of the axle is heated, and the distance increased to ninety degrees as required.

The modes of applying the power for twisting are various; and the method selected is that most suitable to the dimensions of the work. An axle of only four or five inches diameter can be twisted while in the fire, by bolting one of the cranks to a table or to a pedestal fixed in the ground. When one crank is thus tightly fixed, the other crank is conveniently made use of for attachment. A lever is fastened to this crank, and the axle is twisted by a few men at the end of the lever.

When a bearing or pedestal is specially made for such purposes, it is preferable to fix the work by means of caps or clamp-plates across the axle, instead of attaching the plates to one of the cranks. If the axle is thus gripped, instead of a crank, the fixing-bolts and plates may be quickly unfastened and refastened during the process. To facilitate the twisting, a few sledgehammer blows are struck at the moment the power by the lever is applied. Screws also are used to gradually bring the cranks into proper position, instead of applying the power by the lever only; but a few men at the end of a lever which is fastened to a crank or some part of the axle is the quickest mode of twisting all kinds of small axles.

Large axles are twisted under a steam-hammer, instead of in a furnace, and, if convenient, the twist is equally distributed along all that portion of the axle between the two cranks. The axle requires supporting at two places, one bearing being placed to each of the axle ends. One of the bearing-blocks is therefore near the anvil, or, if a large anvil, the bearing may be on the anvil; the other bearing-block is at any convenient place along the axle end. For convenience of handling the work during twisting, the axle ends are rounded previous to attaching the fastenings to the bearing-blocks.

After two or three feet of the axle is heated to a bright yellow, the work is put upon the bearings, and, with one crank beneath the hammer, the work is so adjusted that the crank-pin portion shall receive the blows for twisting ; and during the twisting a space is allowed beneath the crank; all superfluous anvil-blocks are therefore removed from the anvil.

Fixing the opposite end of the axle during twisting is effected by attaching a lever to the crank, or to some part of the axle, and fastening the power end of the lever to a pair of blocks and tackle of sufficient strength. By this means the lever can be shifted during the successive hammerings, that the work may be retained in position to receive the blows. A substitute for a lever of great weight and dimensions consists of a pair of grips having angular gaps for attachment to one end of the axle, the axle end being made four-sided to fit the gaps in the grips. Around the rim of the grip are several holes large enough to contain the end of a strong fixing-pin; and, during the hammering for twisting, the work is retained in position through the fixing-pin being tight in one of the pin-holes in the grip, at the time the pin is also tight in a block or iron post fixed for the purpose.

Another means of facilitating the holding of the work in position may be briefly mentioned, which consists in hooking a number of weights to the lever and crank. The greater the weight thus applied, the more effectual will be the blows of the hammer. Whatever particular method may be adopted for fixing, it is advisable to make the cap or clamp-plates for gripping the work, of thick wrought iron, and with great gripping or bearing surfaces, that the work may be easily tightened in any desired position at any moment while on the anvil.