Ve-neer′--saw.
（
Wood-working.) A circular saw, made thick at the middle, and tapering to a very thin edge at the periphery; used for separating veneers from the solid block.
Veneer-saws for ivory are sometimes made as small as 6 inches in diameter; more generally 15 to 20 inches. They are run at a lower rate of speed than those for wood, and are made to cut as many as 30 leaves to the inch.
Those for wood are frequently of much larger size, are run at a higher velocity, and seldom cut more than 15 leaves to the inch.
About one third the material is wasted in sawdust.
The veneer-saw was invented by
Isambard M. Brunel, 1805– 1808, and it was introduced by him into the
Chatham Dockyard, and subsequently into his works at
Battersea.
A writer of 50 years since gives the following description of
Mr. Brunel's workshop:—
In a small building I was attracted by the solemn action of a steam-engine of 16 horse or 80 men power, and was ushered into a room, where it turned, by means of bands, four wheels, fringed with fine saws, two of 18 feet in diameter, and two of 9 feet. These circular saws were used for the purpose of separating veneers, and a more perfect operation was never performed.
I beheld planks of mahogany and rosewood sawed into veneers 1/14 of an inch thick, with a precision and grandeur of action that was really sublime.
The same power at once turned these tremendous saws and drew their work from them.
A large sheet of veneer, 9 or 10 feet long and 2 feet broad, was thus separated in about 10 minutes, so even and so uniform that it appeared more like a perfect work of nature than one of human art. The force of those saws may be conceived when it is known that the large ones revolve 65 times in a minute; hence 18 × 3.14 = 56.5 × 65 gives 3,672 feet, or two thirds of a mile in a minute; whereas if a pit-saw worked by two men gives 30 strokes of 3 feet in 1 minute, it is but 90 feet, or only the 1/40 part of the steady force of Mr. Brunel's saws. — Sir Richard Phillips's Morning walk from London to Kew.
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Veneer-saw. |
Previous to
Brunel's invention, veneers were cut by sawyers, one of whom stood in a pit. The saw used was similar to the ordinary pit framesaw, but had a thinner blade.
Six veneers to the inch was the customary average.
Hand veneer-saws, very similar to the hand frame-saw, and generally worked by two individuals, were used by cabinet-makers, who would cut 7 or 8 strips to the inch, the slab being held upright in the chops of the bench.
In 1806,
Brunel patented a method of cutting veneers by means of a horizontal knife exceeding in length the block to be operated on. The knife was composed of several pieces of steel, their lower faces being placed exactly in line, slightly rounded, and having a very keen edge.
This had a short reciprocating action, while the block of wood was moved sideways against it by means of a screw slide operated by a hand-wheel.
The block was raised to the proper distance after each cut by means of four screws at the angles of the frame, simultaneously operated by a single winch.
This apparatus converted the whole of the wood into veneers, without waste, and is said to have been tolerably successful with pliant and straight-grained woods, but did not answer well with irregularly grained and brittle woods, as the veneer in this case had a tendency to curl up and split.
See veneer-cutter.
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Veneer-saw. |
Fig. 6950 illustrates the
segment-saw, built up of separate plates of steel screwed to the edge of a metallic disk or chuck.
In those exceeding 4 feet in diameter, the guidance of the wood is effected by a device called the drag.
The veneer generally proceeds from the edge of the saw through a curvilinear trough parallel with its back, but sometimes, as in the present instance, it is conducted away from the saw in front.
The axis of the saw is connected to or disconnected from the steam-engine at will by means of a fast and loose pulley, and a brakewheel at the end of the axle in connection with a friction hoop assists in stopping the motion of the saw. The slab is dogged to the drag, which is carried past the saw by a rack operated by a pinion driven from a band on the pulley
a, and has devices for producing a quick return motion.
A lateral motion is imparted by means of the winch
b, which turns a rod having a screw-thread at each end, which takes into a corresponding worm-wheel
c on a screw at each end of the frame to which the wood is secured.
The screws advance the frame 1/50 to 1/60 of an inch at each revolution of the winch, enabling the thickness of the veneers to be graduated within that amount.
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Veneer-straightening machine. |
The severed veneers
e are turned aside by a feather-edged guide-plate
d (
Fig. 6951), fixed nearly in contact with the edge of the saw, and conveyed away by a curvilinear wooden trough.
