The remainder of the present chapter will be devoted to the consideration of machinery for circular saws; and in treating

* See Retrospect of Philosophical Discoveries, 1808, vol. 1V., p. 222. The following paragraph respecting Newbury's flexible saw, appears on page 527 of the last edition of Belidors Architecturt Hydranlique, avec Notes, par M. Navier, Paris, 1819: -

"Scie a lame flexible et sans fin." - "Cetts intention a Hi proposit en Angleterre, mats il parait qu'on y dontait de son succes. Elle a ete employee arte avantage en Francs par M. Tonronds pour refendre les liteaux qui composent les tnyaux des tis d' Archimede. (Bulletin de la Sociitt d' Encouragement, Juilltt 1815.) Le modeie this extensive subject, it is proposed to present the matter in the following sections.

752 arrangement; saws fixed on lathe chucks.

V. Common applications of circular saws to small works. VI. Common applications of circular saws to large works. VII. Less common, or specific applications of circular saws. VIII. Circular saws and machinery for cutting veneers.

It is further to be observed that in the present or fifth section, in speaking of the construction and application of small sawing machinery, or that which may be conveniently used by the amateur, the matter will be arranged under the following subdivisions.

1. Lathe chucks for very small saws.

2. Spindles for saws of medium size.

3. Platforms, or tables and benches, for saws of medium size.

4. Stops to prevent the vibration of flexible saws.

5. Parallel guides.

6. Sawing the sides of rectangular pieces.

7. Sawing grooves, rebates and tenons.

8. Sawing or cross cutting, the ends of pieces, either square or bevilled; or those works in which the angular variations are in the horizontal plane.

9. Sawing bevilled edges, and prismatic pieces; or those works in which the angular variations are in the vertical plane.

10. Sawing geometrical solids and irregular pieces; or those works in which the angular variations are in both the horizontal and vertical planes.

The sub-divisions 1 to 10, when a little modified, denote also the arrangement followed in Sections VI. and VII.

1. Lathe chucks for very small saws. - Circular saws not exceeding one or two inches diameter, are occasionally mounted on lathe chucks, similar to that represented in fig. 730, which is not only the most simple, but probably one of the earliest modes in which the circular saw was used. The chuck should be of moderate length, with a tenon to fit the hole in the saw, and a central screw or nut to fix the same, as represented.

Opticians use this mode for the small thin saws with which they cut the notches in the tubes serving as springs in pocket telescopes. Carvers in ivory and similar materials employ small but thick saws, the edges of which are of round, angular, or other sections. In eah art the objects are mostly applied by the hands alone.

For cutting the notches in the heads of screws for mechanical construction, thick saws are similarly employed. The screw is held in a socket, fig. 731, the end of which is tapped to receive the thread of the screw, and in cutting the notch, the socket is supported an inch or more from its extremity, upon the edge of the rest for the turning tool. The socket is wriggled up and down as a lever, to make the bottom of the notch tolerably straight, instead of concave, and the precautions to make the cut diametrical will be found at the beginning of page 723.

The gas-burners designated as bat's wing burners have a narrow slit through which the gas issues: these are cut in a similar manner by thin circular saws; and Mr. Milne, gas-fitter of Edinburgh, serrates such saws with a screw-cutter or tap, as in making the teeth of a worm-wheel (see pages 591-2), but the cutter should for the present case have one side of the thread perpendicular, to produce saw teeth of the customary form.

Section V Common Applications Of Circular Saws To  200181

In cutting the knuckles and tenons for joints, fig. 782, the work is usually supported on a small iron platform, fig. 783, the surface of which is horizontal, with a notch to receive the saw, and a cylindrical stem to adapt the platform to the bed piece of the common rest. The platform is fixed a little below the axis, to place the knuckles exactly central to the saw, so as to make the notches equally deep on both sides; and if the surface of the platform is parallel with the axis of the spindle, the notch is sure to be perpendicular or square to the side of the work.

Sometimes two saws are used upon the same chuck or spindle , to ensure parallelism in the sides of the middle piece or tenon; and similar methods are commonly used in sawing, notching, and drilling the small wooden mechanism of piano-fortes. For some of these works, especially those in metal, the saws are not always mounted on lathe chucks, but occasionally on small spindles similar to that drawn in the next figure.

2. Spindles for circular saws of medium size. - For sawing ordinary works in wood, the above arrangements are mostly insufficient; as the saw should be further removed from the pulley or lathe head, to enable pieces of moderate width to be cut off, and also larger in diameter to serve for thicker pieces. The saw is then mounted on a spindle such as that shown in section in fig. 734: the saw plate fits upon the cylindrical neck of the spindle, and is grasped between the two flat surfaces of the flange and loose collar, (which latter is shaded) and pressed forward by the nut. A steady pin, or a small wire (represented black) is inserted obliquely in the spindle, and passes through a corresponding notch in the saw. The steady pin constrains the saw always to travel with the spindle, without depending on the grasp of the nut alone.

Section V Common Applications Of Circular Saws To  200182

The saw spindle, fig. 734, is frequently squared at one end, and has a center at the other, to admit of being supported in the lathe at its extremities, by the square hole chuck and popit head respectively, so as to revolve together with the mandrel. When the saw spindle is used independently of the lathe, it has a center at each end for the center screws then employed, and also a pulley to receive the band from the foot wheel or other motive apparatus. In regard to the proportions of circular saws and some other particulars concerning them, the reader is referred to the table on page 784, near the commencement of the following or sixth section of this chapter.