To produce a good paddle-axle, the smith commences by referring to the sketch by which he is to work, and discovers the places of the bearings in the shaft he is about to make. If no information is given in the sketch about the bearings, he should apply, or take a walk to the individual who ought to have put it in ; and when the smith has learnt something about the intended use of the work, he can commence.

A paddle-shaft has two bearings, one in the paddle-box and the other near the crank-lever by which the shaft is driven. Both these bearings being near the ends of the work, the smith will measure the iron he selects, or the iron he is compelled to use, and endeavour to manage so that what joints may be necessary shall be in some part of the mid-portion.

The whole of the bars selected should be of new puddled iron ; and the first pile made use of, a sufficient length to extend beyond one of the intended bearings of the shaft. Consequently this first pile may be three feet in length and bound together with soft iron binders at both ends, and having a porter or porter-tongs attached to one end. A sufficient length of the pile is then heated to welding so that about two-thirds of the length may be welded at one heat ; or if the furnace is large enough, the whole pile may be welded.

If the shaft is to be twelve feet in length, three such piles will be sufficient for the work, and the two necessary joints will be in the intermediate part, and not in any portion of a bearing.

The convenient sort of joint for such a shaft is a tongue-joint. All such joints require upsetting at the commencement of the welding, that the pieces may be firmly united previous to the second welding or hammering, which closes the iron at the outside of the shaft, but does nothing towards welding the inner parts of the joint.

After the preliminary upsetting with a pendulum-hammer, this second welding is administered to the shaft while in the ordinary horizontal position on an anvil.

The best sort of paddle-shafts are made of one thick lump, that is drawn down to the diameter and increased to the length of the desired shaft; the work being handled or rotated with a porter during the forging.

If the original piece is soundly made of good iron previous to the forging of the shaft, the work will be as good as iron can make it; having no tongue-joint in any part; neither requiring upsetting in any place, so that the mode is also economical, if the good piece to commence with can be obtained. A component piece of this character with a porter attached, is shown by Fig. 172.

The particular shape of the piece is of no consequence. If it should be a two or three feet cube, the smith proceeds by making it into a bar of four sides, and increasing the length to about double. He next places one of the corners to the hammer and makes the work six-sided, and by afterwards half rotating the bar it is made eight-sided.

The length of bar that can be drawn at one heat depends upon the capacity of the furnace for heating, and upon the sort of crane in use. The better the crane, and the greater its capability of moving the work forwards and backwards, the greater is the economy of time in working the several heats. However large the furnace or the hammer, however great the length of iron that is heated, the metal must become too cool to work, if a greater length of iron is heated than can be managed at one heat with the crane.

Drawing down is facilitated by first heating that portion which is nearest to the porter; this part is reduced until the metal requires another heating, which is given to the adjoining lump to reduce it to the dimension of the part already drawn. The largest part is again heated and drawn down, to make the whole length of the bar about the same diameter; by such a series of heatings and drawings, the unreduced lump is always at that end of the work furthest from the smith or smiths, which is its proper place, both for convenience of reducing, and to prevent cracks or unsolid parts being formed at the shaft-end, which often happens when the end is much drawn previous to thinning the middle.

By thus drawing the shaft so that the unreduced lump is always at that end which is furthest from the porter, the work is made sound, and the fibres are put into the desired condition of parallelism with the length of the axle. Towards the conclusion of the drawing or stretching, angular gap-tools of suitable dimensions should be applied to the metal at welding heat, and with especial care to well close the parts intended for bearings. The only portions of a shaft that require a granular or crystalline form for the constituent particles are the bearings. For this reason the smith may give an extra hammering with angular-gap tools, and also with curved gap tools, to these parts, and while the iron is below redness, about 600° Fahrenheit.

When the shaft is reduced to its dimensions, smoothed, and also straightened by means of a long straight-edge or cord, as previously described, the work is cut out from the two ragged lumps at the ends of the shaft, one being the porter-lump and the other the unreduced lump. This piece is that which is first cut off; and the work is next heated at the porter-end, and a tongs fixed to the finished end of the shaft. The ragged porter-piece is then cut off, and a sound shaft is the result. A straight shaft of this sort is represented by Fig. 175; which is an ordinary shape at the conclusion of forging.

Large paddle-shafts are sometimes taper, and are forged taper ; the shoulders of the bearings also are formed during forging, by either reducing the adjoining parts, or welding collars to the shaft at the ends of each bearing. Such collars for bearings are welded to the shaft, after the cylindrical or taper character is produced; the making of the original piece is therefore nearly the same for shafts of all sizes, whether taper or cylindrical. A taper paddle-shaft is shown in Fig. 177.