Fig. 429 is a side elevation, partly in section, of a modification of the foregoing machine when made self-acting to a greater extent. In this case, the table D revolves upon a vertical axis, but in other respects is arranged to act in the same manner as the table in Figs. 426, 427, and 428. The cutter spindle / revolves upon an axis which is in clined with respect to the axis of the shaft o, hy which an effect correspond ing t,o that of the first machine is obtained ; it revolves in hearings in a carriage C, which is fitted to slide at right angles to the axis of revolution of the cutter spindle. A worm w, fixed on the shaft o, and gearing with a worm wheel fixed on a cross shaft v, imparts a comparatively slow revolv ing motion to the shaft, which revolves once during the recessing of a back or handle. Upon the shaft, is fixed a cam I, on which rests one end of a lever w, which is fixed upon a shaft J mounted in bearings. TJpon the same shaft, is fixed a second lever x, the free end of which is connected by a link x ' with the carriage C. This connection is made capable of adjust ment. In the figure, the link is jointed to a nut, in which works screw y, mounted in the carriage in such a manner, that when the screw is turned, the carriage is moved in one direction or the other, while the nut remains stationary. The cam acts upon the lever w, to effect the sliding of the carriage C in the direction indicated by the arrow. A weight L, attached to a chain which passes over two carrier pulleys z z, tends to move the carriage forward in a contrary direction to that indicated, and thus keeps the end of the lever w pressed upon the cam. A second cam M acts upon a lever a' mounted on the shaft J, and connected by a rod bi with the strap guide bar of a counter shaft motion, from which the cutter spindle and the shaft t are driven. When back to be recessed is fixed upon the table, and the machine is set in motion, the cara J slowly raises the end of the lever w, by which the carriage C and the cutter spindle are moved in the direction indicated, and the recessing is effected. When the recessing is com pleted, the cam permits the weight to move ba,ck the carriage C, and, during this backward movement, the cam M begins to depress tbe end of the lever a', and thus to shift the strap which drives the counter shaft on to the loose pulley, so that by the time the backward movement of the carriage is completed tho a,ction of the machine is arrested.
Brushes with Celluloid Backs.—In making brushes with hacks of celluloid or other similar eruh stances, the material is formed in moulds in two parts called half-shells. One of these is perforated with a series of holes for the tufts of brit3tles, whose inner ends are secured by being matted or ironed down upon the under side of the half-shell. A thin sheet of plastic material is now laid on, to further secure the bristles and keep them in position, this being covered with a wooden core extending into the handle of the brueh, and strengthening it. This again is covered with the other unperforated half-shell, which forms the back of the brush, and the whole is then subjected to heat and pressure in a die, so as to mould the composition together, and close the holes about the tufts. In this way, a strong, cheap, and durable brush is obtained, in which there are no seams or joints to open during use, no cement to crumble and admit moisture, and no threads or wires to break off or rust aut.
Brush-making is a trade which may be carried on upon almost any scale, according to the capital at command. A man may start alone with half a dozen tools and a five-pound note, or he may employ hundreds of hands, and any number of machines driven by steam. The manufacture is not confined to any particular place or country, but is spread promiscuously over every civilized land.
Imports and Exports.—The imports of brushes to or exports from the LTnited Kingdom are so trifling as not to be specified in the trade returns. The imports of bristles for brush-making, in 1877, were, from Russia, 1,162,634 lb. ; Holland, 209,457 lb.; China, 100,006 lb.; Germany, 960,614 lb. ; 'United States, 73,045 lb. ; Belgium, 63,557 lb. ; France, 57,8941b. ; other countries, 26,253 lb. The exports for the same year were, to Belgium, 41,175 lb., value, 3219/. ; other countries, 57,780 lb. value, 8649/.