The oilstone, like the grindstone, requires uniform wear to keep it in good order.

Next to the "Turkey oilstone," the "Charnley Forest" is esteemed by joiners and others as the best for giving a fine edge to various tools. The stone should be fixed in a wooden case, provided with a cover to exclude the dust when it is not in use. Sperm oil is the best for sharpening purposes; but neatsfoot is cheaper, and may be considered as a fair substitute, being devoid of unpleasant smell, and not liable to thicken.

The plane-iron should be held at a constant angle of about thirty-five degrees, and must be kept square across the face of the stone. If the stone be narrower than the iron, the latter must be worked from side to side, to reduce the corners uniformly with the middle. If the iron be set askew, so that one corner moves in advance of the other, the foremost corner will be ground away too rapidly, and the edge of the iron will no longer be square to the sides. When the edge is required to be slightly rounded, as for rough work, a light roll must be given to the blade edgeways, but a decided, though small chamfer, should be imparted to the irons of smoothing-planes, and as distinct in its formation as the larger one made by the grindstone. Much pressure should be avoided, as the edge is liable to bend over, and become what is called "wire edge." The flat side of the iron must now be laid quite flat on the stone, and gently rubbed a few times to remove any "wire edge" which may have formed. Under any circumstances, this finishing process is advantageous.

If the iron be held too upright, the edge is more quickly produced, but it will remain sharp for a much shorter time than if it had been set at a lower inclination. It is obvious that if the iron were sharpened at an angle of forty-five degrees, which is the pitch at which it is fixed in the stock, the chamfer formed by the oilstone would rest on the work, and consequently would act only as a burnisher. On the other hand, if the angle be very acute, the edge will be too thin to be durable; therefore the angle of thirty-five degrees already stated appears as favourable as any.

The irons of the jack and other long planes are ground with a large curve or arc, to make the centre part of the blade slightly in advance of the corners. This method has the effect of reducing the labour which would otherwise be required to urge the plane forward. The irons of smoothing-planes, though made as flat and straight as possible on the edge, are, nevertheless, slightly rounded at the corners, to prevent their leaving marks on the work.

The workman judges of the condition of the cutter after setting it on the oilstone, partly by the eye and partly by sense of touch. The edge may look regular and sharp, yet it may not be sufficiently keen to penetrate the hardened skin of the hand when gently drawn across it, which is the almost universal test to which the cutter is applied before reinserting it in the stock.

The cutter being satisfactorily set, the break-iron must be attached. If the plane is to be used for coarse work, like removing the rough outside of a board, etc, the edge of the break-iron may be fixed about one-sixteenth of an inch from the edge of the cutter. The sides of the break-iron should be parallel with those of the cutter, and the corners of the latter must be equidistant from the edge of the break-iron. If it be found that one corner of the cutter is nearer the break-iron than the other, the edge of the cutter has not been ground and set square to its sides. If the discrepancy be considerable, the cutter must be reground to rectify the error. If the break-iron be set back one-sixteenth of an inch from the edge of the cutter at the centre, and one corner of the cutter stands below the edge of the break-iron, regrinding is inevitable.

Supposing the irons to be true to each other, they may now be fixed in the stock. The cutter must be laid on the "bed," and be passed down until the edge is level with the sole of the stock. The wedge is next put in, and gently tapped to prevent the irons falling out. The plane must then be held so that the upper corner of the back end may rest on the bench, while the front end is supported by the right hand. The eye can now be directed along the sole, to appreciate the quantity the iron is made to project, by tapping it lightly with the hammer, which is held in the left hand. When the edge appears slightly prominent, the wedge must be knocked in a little tighter, but violence should be carefully avoided. The iron should at all times be slenderly held, otherwise the stock will be distorted. If in driving the wedge forward the iron should also advance, it may be withdrawn by striking a moderate blow on the upper surface of the stock near the front end, and this without altering the position of the plane. Should one corner of the edge project more than the other, the iron and wedge must be slackened by a blow on the stock; the iron can then be set square by a few taps on the opposite corner at its upper end. By a few well-directed blows of the hammer the edge may be satisfactorily adjusted, but some practice is required to regulate the iron so nicely by eye, that the plane will act properly without subsequent correction. It may perhaps be found on trial that the iron does not project sufficiently to cut; a light tap on the top of the iron will probably set this right. Perhaps the iron stands forward too much, and either entirely opposes the action of the plane, or renders the cut coarse and rough; this may be rectified by one or two light blows, either on the upper surface of the stock near the front end, or on the back extremity.

These instructions equally apply to the smooth-ing-plane. This latter being required to produce as smooth a surface as possible, the break-iron is fixed much more closely to the edge of the cutter, the fortieth or fiftieth of an inch being the common measure.