This section is from the book "Modern Buildings, Their Planning, Construction And Equipment Vol6", by G. A. T. Middleton. Also available from Amazon: Modern Buildings.
Horizontal Board-Cutting Machines (Fig. 248), which are now in extensive use, are chiefly employed for cutting thin boards from logs of mahogany and other valuable woods, also for cutting soft woods into boards, planks, etc. They are specially useful for crooked logs, which are difficult to hold and fix in a vertical frame or circular saw bench.
The saw, which cuts both ways, is driven at a very high speed; and to enable this to be done the swing frame and connecting rod are made as light and strong as possible, steel and iron tube being the materials of which they are constructed.
The slides are of steel, and are fitted with an arrangement for oiling. The bracket slide, which carries the counter shaft, is fixed to the bed-plate of the machine; and on the largest sizes the shaft can be raised and lowered by screw and hand-wheel, so that the connecting rod can always be kept at the best working position. On the smaller sizes this is not necessary, and the shaft is therefore stationary. The swing frame is raised, lowered, and adjusted by hand-wheel. The travelling bed has a quick motion both ways, besides the variable feed motion when cutting.
Log Frames (Fig. 249) are used for cutting round or square logs into planks, scantlings, or boards.
The timber to be sawn is placed on the cast-iron rack travelling bed, and is held by the strong wrought-iron clips, as shown. These clips, which are attached to the rack bed, have a lateral motion for following the irregularities of the log. Motion is given to the racks by two pinions, one on each side, the pinions being moved by a feed-wheel, which can be adjusted whilst the frame is in motion so as to give more or less feed. The rack bed has a quick motion for running backwards or forwards.
The two uprights join at the top, and at the bottom they are bolted to the bed-plate which supports the whole. The crank shaft runs in three bearings. The connecting rods, which are long, are attached to the swing frame at the centre, thereby giving an easy motion. Saw-Sharpening Machines (Fig. 250) are used for sharpening and gulleting circular saws. They are made to fix on a wooden bench, and to drive by motive power. The swing frame carrying the emery-wheel is counterbalanced, and the fore part of it is made to cant to suit the required angle of the tooth of the saw. The machine is fitted with fast and loose pulleys.
The belt which drives the emery wheel is not shown in the drawing.
In a Trying-up and Planing Machine (Fig. 251) the work is cramped to a travelling table, which moves in planed guides under the revolving cutters, with a variable rate of feed between 15 and 30 feet per minute. The cutter block rises and falls to adjust it for varying thicknesses of work. A true and level surface can be planed upon boards, timbers, etc., although the original surface may be considerably warped or winding; and having planed one side true, the other side can be thicknessed to it by passing the work again through the machine.
Moulding and Planing Machines (Fig. 252) will plane, mould, rebate, tongue-and-groove and work to a thickness all kinds of hard or soft timber, on all four sides, at one operation, with revolving cutters, and they are also fitted with fixed plane irons for planing the under side of the work. The feed motion consists of four fluted rollers, all of which are adjustable, the top rollers being held down by weights. The rate of feed varies from 10 to 120 feet per minute. The top cutter block is made to rise and fall, and the side spindles are adjustable, having also an arrangement for raising and lowering the cutter blocks. Pressure levers and weights are arranged in all parts of the machine for keeping the work in position, and an additional cutter block can be added for beading the under side of the timber This is placed at the delivery end. A separate counter shaft is required with fast and loose pulleys and belt gear, from which the different cutter spindles are driven.
A Vertical Spindle Moulding Machine (Fig. 253) is fitted with rising and falling spindle, worked by hand-wheel and screw, and is made both with collars and also with a square cutter block for holding the cutters. Below the cutter block is a guide collar for working circular mouldings, and there is a slot through the spindle for holding a single cutter. The table is fitted with adjustable fences, so that the opening for the cutters can be regulated, and the machine has springs for holding the work down and keeping it to the fence, and also filling-in collars for the opening in the table. The spindle is of steel carried in adjustable bearings at the top and bottom, and it also has a steel footstep to carry the weight. All kinds of straight or circular mouldings, planing, thicknessing, surfacing, rebating, tonguing, grooving, chamfering, etc., can be worked on the machine.
A separate fence for circular moulding can also be arranged to be fitted to it.