Of all power-driven machines, the most indispensable to the pattern maker is the wood-turning lathe. In a small shop where small patterns only are made, a 14-inch or a 16-inch speed lathe, such as is shown in Fig. 86, may prove sufficient for all purposes; but if only one lathe can be afforded, it should be a regular pattern-maker's lathe, similar to that illustrated in Fig. 87.
The pattern-maker's lathe differs from the speed lathe in that the headstock spindle extends through the left-hand bearing, and is fitted to receive faceplates and chucks the same as on the inside end. The arrangement of the countershaft is also such as to give a much wider range of speed to the lathe head, so that pieces of very large diameter may be turned at a speed proportioned to their sizes. These lathes are also fitted with a hand-feed slide rest - either compound, as shown in the illustration, or a plain sliding tool holder moved by a rack and pinion, as may be desired. The tailstock is arranged with a cross adjustment to facilitate turning long cylinders tapering if required. When not in use the slide rest may be removed from the lathe, and the ordinary tool rest and rest socket substituted in its place for hand-turning. The speed at which a lathe should be run is always indicated by the manufacturer, the countershaft usually running at a speed of 500 to 550 revolutions per minute.
A variety of chucks and faceplates for holding the work are always furnished with a lathe. Some of these are shown in the engraving, the screw chuck being shown at a, Fig. 87, and two of the iron faceplates are shown, one on each end of the spindle.
Fig. 87. Pattern Maker's Lathe.
In addition to these faceplates, which really form the base only for chucking the pattern, wooden chucks must be used between the iron faceplate and the pattern. These wooden faceplates are constructed in a variety of ways by different pattern makers; but for small patterns it is necessary to use only a plain board 7/8 inch to 1 1/4 inches thick, of a slightly greater diameter than the required pattern, and screwed fast to the iron faceplate, as shown in Fig. 88. To this, after being placed in the lathe and turned true, the pattern is attached, as will be fully illustrated and described farther on. For •patterns of a medium size, say 20 inches to 30 inches in diameter, the board should be stiffened by means of a wide wooden bar firmly screwed across the back, as in Fig. 89.
When needed for very large or heavy work, the chuck, in order to prevent vibration, must be strong in proportion. It is best made as illustrated in Fig. 90, in which the front of the chuck, as shown at a, will be least affected by the moisture in the air if left unglued, or at best only tongued and grooved, being held together by the crossbars only, as shown at b, to which it is firmly screwed, without glue. This chuck is simple and cheap, and will be found in practice much stronger and more rigid than one built up of sectors or in a more elaborate way. Turning Gouge. Of lathe hand tools the first to be considered, as also the first to be used, is the gouge. It is used for reducing the stock to be turned, from a rough or rectangular shape to a cylindrical form, preparatory to smoothing and finishing. It is ground and beveled on the back or convex side, and the shape of the cutting edge should be of the same curvature as the inside, or upper side, of the tool. Gouges are made in all sizes, one of which is illustrated in Fig. 91; but for the pattern maker's use four gouges, ranging from 1/4 inch to 1 1/4 inches, will be found sufficient for all purposes.
Before using the gouge, and indeed any lathe cutting tool, the workman should take care to see that the tool rest has been elevated above the center line of the lathe centers, from 1/4 inch for small work, to 1 inch or more for large work. The position of the gouge, when in use, is horizontal and at about a right angle to the tool rest It should not, however, be laid on the rest so as to use only the extreme point of the tool, but should be tilted over, first to one side and then to the other, so as to bring all parts of the cutting edge, successively, in contact with the wood that is being turned.
Fig. 88. Construction of Small Faceplate.
Fig. 89. Medium-Sized Faceplate Construction.
Fig. 90. Strongly Braced Faceplate for Large Work.
The gouge may be used by the beginner without hesitation, as in no position, whether tilted or on its back, will it catch or rip into the wood. The tool should be held firmly by the extreme end of the handle, in the right hand, while the left hand rests against the tool rest, the blade of the tool being grasped lightly with the fingers, and passing through and under the left hand while resting on the tool rest.
Fig. 91. Turning Gouge.