The grinding of plane-irons should be properly done without the aid of artificial means ; but whoever can grind a broad trying plane iron straight across, producing a single facet only, need not be afraid to tackle any other tools. The difference between grinding wide and narrow tools is that the former are more difficult to keep in one horizontal plane against the stone, the tendency of the latter as it revolves being to thrust the iron downwards, with the consequent production of a fresh facet or facets.
Practice will soon overcome the initial difficulty. The iron should be ground until the sharpened edge is nearly but not absolutely effaced. Irons vary in curvature in the transverse direction. That of the jack plane should have from rounding, suitable to the rough class of work which it has to do. But the trying and smoothing plane irons should be almost, though not quite, straight across, since their function is to true and finish broad flat surfaces, whereas if they were rounding they would leave hollows in the face. The nest test for the truth of the irons of the trying and smoothing planes is to place the edge along the face of the plane itself, the iron standing perpendicularly thereto, and to note the coincidence between the edge and the face, which should be almost absolute, the light barely showing between the two near the extreme edges. Then the keen corners are just rubbed off on the hone to prevent the marking of grooves thereby.
Smoothing Cabinet Panels
All the actual rubbing on the hone for the purpose of sharpening must be done on the beveled facet, never on the face, the only object of turning the face over upon the hone being to thrust back the “wire edge,” and so loosen and remove it. The irons are removed from jack, trying, and panel planes by striking a sharp blow upon the top of the stock near the end in front of the wedge. The smoothing-plane is struck on the hinder end in each case, the removal being effected by the re-action of the blow. Battered planes look very unsightly, hence the hammer should be applied so that its broad plane and not the edges shall strike the wood, and the wedges should not be very tight, since one, or at the most two, sharp blows should be sufficient to release the iron.
Bead, molding, hollow and round planes are released by striking beneath the shoulder at the upper end of the wedge. The amount of projection of irons beyond the face is gauged by taking a sight down the face, when it is easy to see, not only whether the projection is correct in amount, but also if the irons stand square and equal across. Minute adjustment is made by tapping the stock with the hammer to diminish projection, by striking the iron to increase it, and by tapping it sideways to bring it parallel and square across.
These, then, are the most important points which concern planes. Considering how valuable these tools are, being in perpetual request, it is not to be wondered at that workmen and competent amateurs should take pride in maintaining their planes in proper efficiency. The quality which is of most importance in edge tools is temper. This cannot be known except by trial that is, by grinding and sharpening, and applying the edge against hard, harsh, and knotty stuff, to learn how it stands notched : the edge of a soft tool will turn over almost immediately. A hard, even, though somewhat brittle, tool is decidedly preferable to a soft one, because by grinding; its angle rather large or ” thick ” it will cut very well, while a soft tool will not keep its edge under any conditions of grinding. The quality of a cutting tool cannot always be estimated from its first grinding, since. it may be unsatisfactory then, and improve after kin. or kin. has been ground off ; hence a fair trial should be given by grinding back to that amount. Next to temper, there should be accuracy of profile.
A paring chisel or gouge intended to be straight should not be crooked, since the face ought to be, in large measure, a guide to true cutting. A gouge, moreover, should be of a regular sweep, not of varying radii, flat and quick alternately, and a chisel-face should be so flat across that, when it is rubbed on the hone, contact should occur all over the surface, showing that it is not even slightly hollow or rounding. Finish, that is, polishing, counts for little ; but as a rule the best tools have the best finish. Though a well-finished tool may be badly tempered, one that will take a high polish can scarcely be made of inferior steel. Flaws are not of rare occurrence, being caused by the hardening process. They can seldom be detected until the tool actually breaks ; but if fracture is due to the presence of flaw, its locality and extent will be apparent by a dark spot, like that produced by the stain of citric acid. Then, if the tool is taken to the salesman, he will, if it has been war-ranted, exchange it for another. The mode of grinding chisels and gouges is varied slightly, according to the nature of the work which they have to do. Thus, a tool ground for use with the mallet should not be so keen as one employed for paring only, and a tool for bard wood should not be quite so keen as one for soft wood, durability of edge as well as cutting capacity having to be borne in mind. No tool will cut well unless it is kept perfectly that upon the flat face, hence this is rubbed with the gouge-slip or upon the hone, as the case may be, only just sufficiently to turn back the burr fox med by sharpening on the bevel.
The brace and bits are tools which are quite indispensable. A brace and a dozen bits can be bought., and better sets at prices ranging. The quality of the bits is pretty much the same, the difference in cost being mainly in the brace and in the number of bits to the set.
And there is this difference in bits, they may be black, bright, or straw colored, the first-named being the cheapest and the last-named the most costly. We do not know- that there is any difference in temper, though the straw-colored kind are usually believed by workmen to be superior to the others. A complete set numbers from thirty to thirty-six, and embraces center, nose, shell, countersink, and some others of a miscellaneous character. There is seldom anything wrong with these when bought new; but in the cheap sets the bits are often not fitted to the spring catch of the brace, which is a point that should be noticed, since when not so fitted the bit cannot be withdrawn along with and after the brace from its hole, but has instead to be pulled out by hand or with pincers. With an unfitted set, either file the notches yourself in all the bits alike or buy a common iron brace with a pinching screw only. The temper of the bits is necessarily very soft in all cases ; highly-tempered tools would not stand the torsional stresses to which they are subjected. For sharpening these, a smooth file alone, or a file followed by a gouge-slip, is used-Brace-bits will soon get altogether out of order by careless sharpening. Just as we should not sharpen a chisel upon its flat face, neither should we sharpen a center-bit on the outer edge of the nicker.