1040

THEORY AND PRACTICE OF ENGINEERING.

Book II.

to be planed is placed upon a movable frame, which regularly brings it under the action ofthe horizontal wheel, where the gouges and planes attached to it catch the surface in itspassage, and render it at one operation not only plane but perfectly smooth.

A similar machine was contrived at the Royal Arsenal at Woolwich, and the carriageswere moved backwards and forwards under the cutters by hydraulic pressure.

Machines for planing or smoothing Iron are of the greatest utility ; the planing tool is fixedin a frame in such a manner that it can be inclined, if necessary, to any angle; the framehas a motion which allows it to rise up at the end of every stroke, and enables the carriagewhich bears the iron to be planed to pass back free to the cutter: a single workman canthus adjust the cutter at every stroke.

PLANING IRON

Fig. 1596.

The machine generally consists of two parts, the bed on which the table slides backwardsand forwards, and a slide-rest made fast by two upright standards. The tool is held bya transverse slide, and can be lowered and adjusted to cut what is required, by turning ascrew bv a handle placed at the top ; the whole slide traverses to any part of the width ofthe plate by another handle that turns the screw, which passes from one standard to theother.

There are many other applications of the slide-rest to machines and tools, and it has beenfound of the greatest use in all our manufactories of machinery : since iron has been sogenerally introduced for the construction of machines, it has been found necessary to obtaina more perfect metallic surface on it than could be performed by chipping it with a coldchisel and filing it; a process requiring also more time than could be allowed when thedemand became great. The first substitutes for manual labour in smoothing iron wererevolving cutters, the plate of iron to be worked oflf by the aid of machinery being slowlyadvanced under them by the ordinary rectilineal motion ; in some instances the cutter orplane passed over the iron, and in others the plane was fixed whilst the iron was placedbelow, a method now generally adopted.

The planing tool ir. ordinarily fixed in a frame of iron, and can advanced eithervertically or laterally to its work ; it may also be inclined in any required position, as it can

Fig. 1097.

PLANING MACHINE.