A simple class of shapers to be here described are those which work with a to-and-fro movement which causes the cutting tool of the machine to move in the same manner, while the work which is fixed to the machine may be said to remain stationary. In the middle of Plate 35 such a machine is shown, and the principal portions are named agreeably to the plan for naming the lathes. Such a shaper will produce both flat surfaces and circular ones, but the instrument is specially adapted to small flat surfaces whose areas do not exceed one or two feet. The various sizes of shaping-machines are distinguished by the extreme lengths or distances that can be traversed during one effort or stroke of the cutting tool. If the extreme distance is ten inches, the machine is said to have a ten-inch stroke ; and to make the tool travel ten inches, the crank-pin, which is situated at one end of the connecting-rod shown by C R, is fastened at five inches from the centre of the slot-wheel. This crank-pin or adjustable stud is denoted by P, and may be fastened at any desired place along the slot or recess in which one end of the stud is fixed; the stud being fastened with a spanner either near the centre of the slot-wheel, or near its rim, the precise place depending on the length or width of the surface to be shaped. For the purpose of moving the table and thereby the work which is fixed thereon, a traverse screw is provided which is as long as the machine, and in the Figure the screw is shown by T S ; on the outer end of this screw is keyed a teeth-wheel which rotates the screw and moves the table. Engaged with this wheel's teeth is a pawl which is moved to and fro by means of the small levers and rods attached to the traverse plate, denoted by T P. Another screw shown is the head-screw, and is required to move the carriage and head along the machine. In order to raise and lower the table to which the piece of work is fixed for shaping, a screw and wheel are provided at the front of the machine near the workman. At the front of the machine is a worm pinion or screw pinion which works between the teeth of the segment rack, the spindle of the worm being indicated by W, and rotated either by a handle or by the machine itself by means of light rods attached to the moving head of the machine. Both hollow surfaces and convex ones are formed with the aid of this worm and rack ; and when ordinary plane surfaces are being made, the worm is not rotated, but is only the means of adjusting the tool-holder to any particular angle that may be necessary for the work. A backward band is not required for a shaping-machine of this sort; only the usual forward band, with its tight pulley, and a loose one, are necessary, which are represented in the Figure. The particular method shown in the Figure for starting and stopping consists in the use of a vertical rod fastened near the wall, similar to the mode for the lathes; to this rod, a bar, levers, and a handle are connected, the starting handle being in front of the machine and indicated by the name.

In Plate 36 the back of a lathe is represented in order to show the traverse bar and worm. The traverse bar may be either round or square; if square, no key is necessary for the worm pinion, the hole in which is also square and just large enough to let the worm slide easily along the entire length of the bar; if the bar is circular, it is necessary to make a key-way along the entire length, and to provide the hole of the worm with a ledge to fit the key-way. The entire traversing apparatus is worked by means of the traverse band named in the Figure, and the band may be crossed when it is necessary to reverse the direction of the traverse. To avoid this crossing, additional cog-wheels are provided in some lathes, and situated near the driving pinion. Those lathes that are merely capable of moving the carriage along the bed are single traverse lathes, and those that are capable of moving the carriage along the length of the bed, and also capable of moving the slide-rest across the bed, are double traverse lathes. The movement along the length of the bed is termed the long traverse, and the movement across the bed is termed the across traverse. Some lathes have only the longitudinal traverse, and, for these, only one teeth-wheel is required to engage with the worm; but a double traverse requires two wheels and a pinion, because two spindles are provided in the carriage. Both these spindles are at right angles to the length of the bed, and one of them has a screw formed in the mid-portion ; this spindle is the one for the across traverse, and works in a screw-nut which is fastened to the pedestal of the slide-rest, and by the rotation of this screw the tool is made to travel across the lathe, so that the length of this across traverse depends on the length of the screw employed for the purpose. The other spindle is for the long traverse, and has no screw, but has a cog-wheel keyed at one end to work in a long row of teeth which extends along: the entire length of the lathe bed ; this row of teeth is termed a rack, and may be either on the front of the lathe bed, on the back, or situated in the long narrow space in the lathe bed. In order to arrange both spindles so that either one may be conveniently worked without the other, both the spindle wheels must either have room to slide into and out of gear with the worm, or one wheel must be capable of being loosened while on its spindle, so that it may rotate freely without effecting any traverse.

Plate 36

Shaping Machines 43

Those lathes that are not provided with a proper traverse bar are worked by means of the lathe-screw and some of its wheels, and the carriage is made to move at a proper slow rate by using four or five wheels between the lathe-mandril and the lathe-screw. This method may be also adopted if the lathe has a traverse bar, but only in special cases; for ordinary traversing, the traverse by screw wheels is awkward, and involves needless labour, and also an unnecessary wearing of the lathe-screw.

When a lathe is fixed near a wall, as shown in Plates 35 and 36, the wall may be conveniently used for hanging up grippers, gauges, callipers, spanners, and plates; also for fixing shelves to hold cutting tools of all sorts, rings, blocks, poppets, scriber blocks, dotting punches, straight-edges, and measures. A series of shelves may also be fixed for the screwing wheels, so that each wheel is kept apart from the others, and can be immediately lifted and put into the lathe without interfering with any other wheel that may be near it. Another easy mode of arranging the wheels is to hang each one separately on a round iron pin tightly driven into the wall, the pins being arranged in one or two rows, and each pin kept for its own wheel. If any wall should be injured by thus using it, the fact would merely prove that the wall was not strong enough for its use. When iron walls are adopted, a proper fixing of shelves, stays, hooks, and pins strengthen the structure. It may be here mentioned that only such tools as are in daily use by the workman may be thus publicly exposed : all others are to be taken to the tool-keepers, whose duty it is to collect, distribute, and keep in their places the various portable implements that are used by nearly all the men in a factory. If every workman could be made to properly use and manage his tools, and also those which he borrows from his companions, every small tool in the factory might be kept in sight, because this is the only proper means of finding a tool at the moment it is required; but in the present circumstances it is necessary to appoint men to take care of all small implements, and frequently to lock them up, so that much time is lost while obtaining a tool when it is wanted.

In Plate 36 is also shown a drilling arm which is attached to a wall by means of a davit or post belonging to the arm ; at each end of the post is a circular pivot which is gripped by a pair of grips having half-round gaps; of these grips, those two that are fastened to the wall are long enough to effect a firm fastening, and may extend one or two feet along the wall, but the front grips are only long enough to admit the fixing bolts which hold the post in its pivot bearings. The pivots being circular, allows the arm to be swung around to any desired place, and to be there fixed by tightening the fixing bolts with a spanner. Another kind of adjustment is effected by means of a slot in the outer end of the arm ; in this slot slides a block which constitutes a screw-nut in which a screw-pin is represented ; this slot is of sufficient length to allow the block to be placed at the extremity of the arm, or at several inches nearer to the post. To tighten the block at any desired place to suit the work being drilled, a nut is provided, which is tightened with a spanner. The screwed hole in the block is of sufficient diameter to admit a screw a foot in length, when it may be necessary; when a long screw is not required, a short one is used, and the lower end of each screw contains a recessed portion which is hardened, the shape of the recess being conical. Into the recess is put the point of the drill brace when in use, and swing-braces and crank-braces may be thus used although they may not have any screw, because the long screw in the arm can be screwed down by means of its handle to advance the drill into the work during the drilling.