COMB-CUTTING. The old method of forming the teeth of combs is by means of a double saw, which consists of two separate fine saws, placed parallel with each other, and adjusted to such a distance from each other as to embrace a tooth of the required fineness between them. These two saws are so ar ranged that, while one cuts into the comb to the full depth required, the other cuts only about half that depth, and by this contrivance the uniformity of the comb is secured, be cause, while the deeper saw is completing the first cut, the shallower one is forming the com mencement of the second, and when, on the completion of the first cut, the deep saw is put into the second cut to complete it, the shallower one immediately commences a third The cuts thus formed are subsequently en larged and rendered smoother by means of a very thin wedge-shaped file, which also points the teeth. Though this method of comb-cut ting is still practised, a much quicker mode of performing the same operations by means of circular saws and revolving cutters for ing the teeth has been long in use.
By the above described modes of comb-cut ting, all the material of the interstices between the teeth is lost or destroyed, but by the ope ration known as the parting of combs such loss or waste of material may be avoided in the manufacture of combs of tortoiseshell, horn, any tough material. Two combs are
by this process, made out of one piece, the teeth of one being cut, by the pressure of chisel-like instruments, out of the interstices of the other.
An American patent was taken out in 1830, by Mr. Ives of Connecticut, for making me tallic combs by the following method. A strip of sheet metal is prepared, of a width equal to that of the intended comb, and of a thickness equal to that of the intended teeth. The piece of metal is bent or plaited in a zig,-zag, man ner crosswise : the bends being of such width only as shall adapt them to the forming of a single tooth. The bending is effected by a sort of crimping rollers; and these plaits or bent portions are placed up together, being kept separated by a distance equal to the in terval between the teeth of the intended comb. Ribs are soldered to make the back of the comb ; and the two surfaces are smoothed or cut away, so as to separate the several plaits, and make each one stand singly as a tooth of the comb.