Angles of Cutting Edges - Workshop Practice - Grinding and Sharpening Edge Tools - How to Hold Them - Sharpening Scrapers.

THE importance - indeed, I may say the absolute necessity - of keeping tools in good order has already been referred to, but it would be little use to tell the novice this unless he were shown how to get them in condition for work and keep them so. Half the battle, no doubt, is to get them right at first, for they are kept so with comparative ease then. To attempt good work without properly sharpened tools is quite out of the question, and there are, I imagine, few readers who will be unable to get a cabinet-maker or joiner to show him a few tools sharpened just to give him a start.

I say this, as many amateurs seem unduly concerned to know all about the correct scientific rules which govern the sharpening of tools, the proper angle, and so on. Well, let me tell such that in the practical workshop these matters are not regarded. No one ever thinks of measuring the angle; he knows about what suit, and that is sufficient. If, then, the reader will look at Fig. 7, on page 84, he will be equally well-informed, and he need not bother about measuring angles. The cabinet-maker is working in wood, be it remembered by those who do not care about 'rule of thumb' work, and, for all practical purposes, an edge that will do for one kind will do for another. If I may say so, without any one supposing that blunt tools will do at any time, the softer the wood the sharper the tool should be to ensure a clean cut. This, though, is more theory than anything else, for a chisel which will cut oak cleanly and perfectly will do the same with pine. To reduce theory to practice, which, after all, is the main thing, at present at any rate, a cutting edge may be tried across the grain of a piece of pine or other very soft wood. If it makes a clean cut, not a tear or a bruised - looking one, it will do for any wood, and may be considered quite satisfactory. This hint, to those for whom I am specially writing, will be in practice worth a volume of theory.

In many, perhaps the majority of cases, the purchaser of new tools will be able to have them delivered properly ground. If not, and he does not possess a grindstone of his own, he will have no difficulty in finding a carpenter or some one who has one. It may be said that any tool-shop will undertake to grind tools, but it would hardly be fair to get this done locally if the things are bought elsewhere - that is when they are new. Re-grinding is a different matter somewhat, and tools, properly used, do not often require this. Of course, if their edges get notched, they must be reground before they can be sharpened. Grinding, it may be explained, only partially sharpens the tools, the cutting edge being afterwards given with the oilstone. It might be done with the latter only, but the labour would be greater than necessary. Grinding is somewhat dirty work, as the stone has to be kept wet with water, and also laborious. If some one can be got to turn the stone it will be easier, besides leaving both hands free to hold the tool, which must be kept steadily in the right position, for a clean bevel is wanted, and not an edge shaped like Fig. 70. To get a straight edge across the blade is not less important, for if this is ground away more on one side than the other, or rounded off towards the corners it will be defective for most tools. The aim should be to get a straight and sharp edge as represented in side and front view by Fig. 71. The stone may be turned either to or from the edge being ground, but the former is the better way. When turned from the tool there is considerably more risk of a 'wire' edge, a kind of loose burr, being formed. The grinding should be done only on one side of the tool, and not on the flat as well. With a little care no great difficulty will be experienced in grinding properly. Tool holders have been devised for keeping the edge evenly on the stone.

Fig. 70   Badly Ground Edge.

Fig. 70 - Badly Ground Edge.

The oilstone has been referred to, so nothing more need be said about it. To use it properly, that is, to put a keen edge on, requires a little knack, and beginners often seem to experience some trouble in sharpening, though there is really very little difficulty in doing it. The stone being lubricated with oil the tool should be rubbed firmly backwards and forwards, not jerkily or anyhow. The handle or end of the tool may be held in the right hand, and the left presses on the blade. At first the pressure on the stone may be fairly great, but as the edge becomes sharper it should be decreased till, for the last rub or two, it is almost nothing. The tool should be kept as kept as nearly as possible with the ground bevel flat on the stone, just raised enough to ensure a sharp edge being formed. If held more upright it would not at first much matter, but regrinding becomes necessary sooner than it otherwise would. To remove any wire edge - indeed, in any case - after sharpening as directed, lay the other side of the chisel or tool on the stone, on which it should be flat or nearly so, and give it a rub or two in that position. Of course, the same general precautions must be observed as when grinding, and with a very moderate amount of practice the novice should be proficient in sharpening his tools. Saw sharpening need not be further referred to, as it was sufficiently dealt with elsewhere.

Fig. 71.   Properly Ground Edge.

Fig. 71. - Properly Ground Edge.

The scraper, to those who are not acquainted with its powers, may seem an insignificant tool, and hardly worth attention in sharpening. The fact is though, that unless this is done properly, the scraper is practically worthless, for it simply rubs instead of scrapes. As the edges are alike they may all be sharpened, but usually only one of the long ones is. If the steel is not in condition when got, the edge, assuming it to be for flat work, must be made straight either on the grindstone or the oilstone. To make it perfectly square it must be rubbed on the oilstone while being held upright. Now comes the important part of the sharpening. One end of the steel resting on the bench top, the other is held by the left hand, with the edge to be sharpened towards the worker's right. With this one draw the scraper sharpener smartly upwards, firmly pressing it against the edge, two or three times. Reverse the ends of the scraper and repeat. Mind that the sharpener is held square across the edge of the scraper, or, instead of being sharpened, with a slight tendency to burr, it will be round. To make all clear, the edge should have sharp angles, as represented in Fig. 72, and not round, like Fig. 73. A properly sharpened scraper will remove shavings in a manner which might astonish the novice who has never seen one used.

Scraper EdgeScraper Edge, sharp; Ditto, round.

Figs. 72 and 73 - Scraper Edge, sharp; Ditto, round.