Figs. 978.

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979.

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Note AM. - To follow note AL, on page 495. (Mr. S. Nicholla' Stop or Clamp for a Joiner's Bench.)

Fig. 980 is a perspective view, and fig. 981 a plan of Mr. S. Nicholls' subsequent contrivance for the same purpose, and rewarded by the same society in 1843. Two inclined and undercut slips of wood a a, are firmly screwed to the bottom board, and between them are loosely fitted two pieces b b, nearly counterparts of a a, but with projecting fillets at the end. When the board w, is inserted between these loose jaws, or chaps, they are thrust forward until they reach that contracted part of the angular gap, which compresses them firmly upon the board to be fixed This mode serves for a much greater range of size in the pieces fixed than the last, and the straight faces of the jaws do not indent the works, as may happen when soft woods are clamped in the vice shown in figs. 978 and 979. See Transactions of the Society of Arts, vol. 55, page 42.

Figs. 980.

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981.

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Note AN, page 504. - To follow the paragraph commencing " The Scale-board plane" (Messers. Esdaile and Margrme's Scale-board Machine.)

The scale board machine used by Messrs. Esdaile and Margrave, at the City Saw Mills. London, has a wide out-iron elide plate, that works freely in chamfer ban elevated on framework about six feet above the ground; the power of the steam engine is applied to the slide by means of a stout leather strap, or rather by two straps for the to and fro movement; but one is always out of action and loose. The slide is perforated for a cutter upwards of one foot wide, placed beneath the slide, and inclined horizontally about 40 degrees, as a skew rebate plane, but the pitch of the iron or its vertical face, up which the shavings slide, has only half the inclination of the horizontal, or about 20 degrees.

The log of wood, which is preferred wet on account of its superior elasticity in that condition, is held down by heavy weights, whilst the metallic plane slides' beneath it and shaves off in an admirable manner one single shaving; the thickness of the same is determined by the adjustment of the cutter, which is principally held by wedges.

Messrs. Esdaile and Margrave recently patented the employment of throe cutters situated as above, but one behind the other to remove three scale-boards in immediate succession; the scheme was effectual in its action, but in the end less economical than the single cutter - and which must be moved by a strap or rope, as although racks and iron chains have been tried, they fail apparently from the want of sufficient elasticity.

Note AO, page 505. - To follow the second paragraph. {On Machines for Planing Wood.)

Of the machines for producing works in wood, similar to those usually accomplished by hand planes, several have been constructed to act by means of cutters having circular motion. Thus in Paxton's machine, various circular saws or cutters of different diameters and forms are placed on one spindle beneath which the sash bar is traversed. In machines for planing mouldings from 2 to 8 inches wide, for house joinery, picture frames, etc, two figured cutters of the entire width of the moulding are screwed to a rectangular block fixed on the revolving spindle, by which means the cutters are presented at the proper pitch or inclination of 60 or 70 degrees to the face of the moulding. Circular cutters were also used in the earlier experiments with Burnett and Foyer's machine, some of them with only 4, 5, or 6 edges or teeth constructed very nearly on the principle of ordinary plane-irons.

But circular cutters were abandoned by Messrs. Burnett and Poyer from two motives; first, the difficulty of constructing and sharpening them, and secondly, that notwithstanding the rapidity at which the cutters might be driven, they still left marks upon the work because there is a distinct, though small interval of time, between the passage of the one cutting edge and that next following, and during which small interval, the uninterrupted advance of the work allowed certain portions to be less reduced, or left as little hills and ridges slightly above the general surface The wood only becomes absolutely smooth, when its traverse is so far diminished, that one point of the cutter, (or probably the highest point of the entire series,) is enabled to touch every individual portion of the work, and which requires a much greater reduction in the feed or traverse, than might be expected, thus mostly leaving something to be smoothed off or removed by hand tools. Messrs. Burnett and Poyer from these circumstances ultimately rejected revolving in favour of fixed cutters, and thus in planing mouldings, they employed a stock which contained from twelve to twenty cutters, every one figured and secured by a separate wedge, so that the first cutter penetrated but little into the moulding, and that every succeeding tool removed a shaving of its own; all the cutters gradually assimilated more and more to the last of the series, which was sharpened exactly to the form of the moulding. Under this arrangement the machine was enabled to work mouldings in pine wood, at the enormous velocity of 70 lineal feet per minute, and still the work had all the smoothness of that produced by the joiner's hand planes as usual.

Note AP, page 505. - To follow the former note having the same reference. (Mr. Antonio Mayer's Patent Splint Cutting Machine.)

The production of an article of apparently minor importance, has led to the invention of a very effective and important machine allied to the planes, namely, the splint-cutting machine for cutting the wood for chemical matches.

It is necessary to premise that when these useful matches were first introduced, they were mere shavings cut from blocks of deal, by the plane previously used in preparing the chips of willow and other woods from which ladies' bonnets are woven. This plane had at the front, a series of lancet-like knives which scored the wood in shallow parallel furrows, and immediately behind the knives was fixed an inclined plane iron of very low pitch which cast off a shaving, thus producing several splints at once from the edge of a board about one inch thick.