important machine in blind manufacture is shown in Figure 4. It is designed to dress with the grain all four sides of a slat, thus saving a large proportion of the rough slats made where one side is dressed in the opposite direction. There are two tables, one lower than the other; the material is fed over the lower one and under a cutter-head that dresses one side, and as it leaves the cutter-head the ope rator reverses it endwise and passes it under the feed-rolls above the upper table, when it is carried to cutter-heads that finish it on the opposite side and edges.
Cullers for illoulding and days of working out mould ings and of matching flooring by hand-tools operated like planes have gone by; instead of sliding a cutting-tool along stationary work the stock is fed along, to be worked by rotating cutters, which give the proper profile. By this, speed is multiplied almost beyond computation and the quality and the accuracy of the work are greatly increased. A good machine is of very little use unless it is supplied with proper cutting-bits, and these are useless if difficult to sharpen and keep in order or if likely to lose the size or pro file corresponding to the surface which they are intended to produce. This is particularly true with matcher-heads for wood-work. In this respect a very important step has been made in the circular bit-head (jig. 3). Each bit is ring-shaped and carries the outlines of the pattern which it is to cut. The entire outer circle is tool cutting-edge. The bits are fastened to the rotating head by bolts and nuts, making a strong and durable tool which has weight "low down" and in the line of the cut. For matching, these heads are arranged in two series, consisting of upper and lower bits, that divide the chip upon a central line of cut. First one bit makes a cut, to be followed by the next one of the other series;, therefore the entire cut is not made by one stroke, but by first one and then the other series, to complete the full outline of the shape to be produced. This divis ion of cut demands special adjustment of the bits, giving them side clear ance, the same as a new tooth when set, by securing them to their respective seats in the slanted position, so that no part of the bit but the cutting-edge shall come into contact with the lumber.
'With the latest improvement the heads carry the bits that belong to the several series on opposite sides of a central flange, thus adapting the head to any expansion or change of tongue or groove. As the bits are
worn down by work and sharpening they are turned around on their seats until worn down to the safety-point, which does not leave much of the material. To make the tongue and groove tight or loose, the tongue- and groove-cutters are furnished with washers open on one side, and the bits are loosened up, to slip them under. To set the cutters there are employed gauges fitted to their slanted edges, showing the angle at which to file them in order to keep the head to full size.
A good cutter (p1. 14, figs. 5, 6) has a cutting-edge formed by milling into the face of the steel instead of cutting the desired shape of the mould ing on the edge and then grinding it to a bevel, which latter method makes the form of the cutter liable to be changed in grinding. Where the form of the moulding is worked in the face of the cutter the bit is sharpened by simply grinding the edge to the standard bevel of the bit. These cut ters are placed on the head with the ground angle toward the direction of rotation of the head, thus making the cut of the bit come at right angles to the surface, giving a scraping cut and leaving a perfect surface for fin ishing. These cutters are more readily set than those of the old style.
Tenoning-machines.—Tenons may be produced (I) by saws, (2) by rotat ing cutters, or (3) by both. When produced by saws (p. 71), the material may be removed as a block, no stock being destroyed except that from the saw-kerfs; or the saws may be set wobbling, so as both to remove and to disintegrate the material. Where rotating cutters are used they may have their axes parallel to the length of the tenon (in which case, even for a single tenon, two separate cuts must be taken by as many beads or the end of the stick must be passed twice over the cutter), or the cutters may have their axes at right angles to the length of the stick, cutting a single, double, or triple tenon by employing two, three, or four sets of cutters in the same head, with a space left between for the tongue or tongues. Saws have the advantage over cutters of taking less power on large-sized tenons, but as their work is rougher, the cutters are more used. Most ordinary matching-machines will do tenoning as one part of their regular work, but there are many tenoners which do little, if anything, else.