Smoothing proper, or polishing, is distinguished from other surfacing in that it little alters the dimensions, proportions, or shape of the article worked upon. It is done with sand-paper, emery-paper, or glass-paper, and by emery-wheels, the latter being used only in machines and the others both in machines and by hand. Examples of machines smooth ing by the aid of sand-paper are shown in Figures 2 and 3 (pi. IS); and of those employing emery-wheels, Figures 8 and 9 (p1. 19). The result ant waste is in the form of fine dust.
is done by punches used in the hand in connection with a mallet, or by rollers or dies bearing a pattern in intaglio or in relief. This class of work is for ornamentation only, and there is no waste. It is very considerably employed in the cheaper grades of furniture and in architectural decoration. Another and special class of compression, employed in making round-sectioned matchasplints, is done by forcing the wood block end-wise through holes in a steel (lie-plate.
Pressed moulding, on which there is a pattern like that made by carv ing-too]s, but not under-cut, is made by passing moulding which has approx imately the desired cross-section between two rolls, one plain and the other incised with the pattern designed to be raised. Good types of such ma chines have adjustments for pressing curved panels used in chair-backs, leaving a plain margin all around the figure.
construction runs so largely to spe cial machines and to making interchangeable parts in multiplicate that a large class of machines has been produced to effect this end in almost every important branch of mannfaeture—notably in making carriage- and wagon wheels. Some of these are very ingenious, and their work is more rapid and accurate and better finished than would be possible by hand.
In an unproved wheel-tenoning machine (A/. IS, fig. 5), for equalizing spokes and tenoning them after they are put in the hub, the "spider" is held between two cup-like clamps. By the motion of a treadle one spoke is grasped near its end between two V-shaped jaws; an equalizing saw with its mandrel at right angles to the axis of the wheel cuts off the spoke-end. This saw is mounted upon a hollow arbor and has in its centre a hole, through which the tenon-cutter passes, the saw being held to a face-plate by countersunk screws. By a one-hand lever the saw is brought across the tenon-end, and by another the tenon-cutter is advanced. The clamps which hold the hub are mounted upon two sliding bars, to permit adjustment for different diam eters of wheels. Both hands of the operator are free to work the auger and
revolve the wheel.
For boring rims and felloes there is employed a machine with hor izontal auger, the rim being held upon a semicircular table, which is reversible, so that boring can be done from either inside or outside. There are gauges to regulate the distance between holes, and the rim or felloe is shifted around against a set of friction guide-pins which determine its centrality. For curving and finishing the inner curve of rims and felloes a machine is used having two adjustable mills with their edges somewhat circular (fig. 4). The clutters are set closer together or farther apart for different thicknesses of felloes. The edges of rims and felloes are planed in parallel planes by passing them between two hori zontal cutters, a curved feed being given by forming-plates and the feed being effected by readily set live-rolls. The angle of the feed-rolls can be changed to suit different wheels. The knives are set at an angle for a shearing cut, thus producing smooth work and preventing tearing. Bev elled rims are produced by tapering cutter-heads.
A hub-roughing and finishing machine (pi. 16, 4) clamps the block between a live and a dead cone-spindle, the former being rotated by a friction disc. A table having transverse motion bears two stands, one haying fastened to it a roughing-knife and the other, upon the oppo site side of the spindle, bearing a set of knives of proper shape to finish the hub. All the knives stand at the angle at which an experienced fin isher would hold a hand-tool to do the best work. The roughing-knife has its cutting-edge down. In the hub-boring machine the hub is clamped horizontally between two V-shaped jaws, and the auger is run down through it by a rack-and-pinion feed, the overhead pulley being a drum, to accommodate the lengthwise motion of the auger. Taper ream ing of hubs is done in a machine having cup-shaped clamps for the hub ends, the two clamps being held upon a carriage having motion in a line with the axis of the hub. A taper reamer receives rotation from a shaft at the other end of the machine. The work is fitted by clamping the hub in position and moving the carriage along by rack-and-pinion feed operated by a hand-wheel. Elm hubs are sometimes bored before rough ing, the machine somewhat resembling that for reaming, except that the blocks are held between steel spurs instead of cups.