Читать книгу A Boy's Workshop: With plans and designs for in-door and out-door work - Harry Craigin - Страница 7
ОглавлениеIV.—USE OF TOOLS.
WE begin with the saws, of which you have two: cross-cut saw, and splitting saw.
The use of a cross-cut saw, as the name implies, is to cut across the grain or fibre of the wood: it is one of the most indispensable tools we have. The teeth are finer and closer together than those of the splitting saw, which, as the name describes, is intended to cut with the grain, usually lengthwise, of a piece of wood. Never try to substitute one for the other, for you would injure your tools. When you want to use a cross-cut saw, the saw should be held at an angle of about forty-five degrees, and must also be held steadily without swerving to the right or left; otherwise the teeth of the saw will stick, and you cannot make a clean cut.
You will observe in looking at a saw that the teeth are set, as it is called; every other point turning a little away to the right or left of a straight line; the reason of this is, to make the cut wider than the saw blade; otherwise after cutting in a little way the friction would make the blade bind. Saws are, or should be, in proper condition to use when they are bought; if not, or if by any accident the teeth should get bent, you must have the saw set without meddling with it yourself.
A splitting saw is used differently from a cross-cut saw; it should be held more nearly upright; the cutting is always done on the down stroke. Never press the saw against the wood; the teeth will catch, and the saw bend, and the wood won’t be cut if you add any weight to that of the saw itself.
There is a certain amount of knack required in order to saw well, but practise will improve even the most awkward workman. Always saw slowly and easily, in a sort of regular time. Be sure the wood is held firmly and doesn’t hop.
USE OF PLANES.
We have jack-planes, smoothing-planes, and block-planes. When you want to make aboard thinner, or smoother, it has got to be planed; also the sides and edges of a board are sometimes rough, or you wish to bevel them.
If the grain of the wood is perfect, there is no trouble about planing in either direction, but generally the grain runs in a slight slant or angle to the surface of the board instead of parallel to it. If, then, you start your plane and plane “against the grain” of the board, the edge of the plane will catch in ends of the grain lines, and the surface will be chipped instead of smoothed. If, however, you start it and plane “with the grain,” the ends of the grain lines are smoothed down, like the feathers on a bird’s wing when you stroke it down instead of up. So it is well to be sure about the grain before you begin to plane. Sometimes the grain is twisted and runs one way in one part of the board and another way in another part in a wavy line. Then you must vary the planing according to the surface. You would soon learn these simple things perhaps, but to know them at the outset will save you some vexation.
The smoothing-plane is much shorter than the jack-plane, and is used for smoothing smaller pieces which would be lost under the jack-plane, and also for smoothing inequalities left by the jack-plane. I have put no smoothing-plane on your list, as for ordinary work the block-plane can be used as a smoothing-plane. Thus: Turn the small thumb-screw at the front of the block-plane and press it forward; this opens the mouth of the plane so that the plane can be set more and cut a larger shaving.
Now for the proper use of the block-plane, remembering to restore it to its original set if you have been using it as a smoothing-plane. To smooth the ends of boards you need a small plane which can be set very fine; i.e., with the blade projecting very little from the face of the plane, and with the mouth so closed that the blade will not chip in cutting.
One important principle must be practically learned before you can do good work: Everything in carpentry from beginning to end must be done on the square. In planing, above all things, the square must begin every bit of work, and end it, and be used to test it, all the way along; it is just what the name implies, a try square; so perhaps the next thing explained had better be some of the uses of the square.
To give all the uses of this apparently simple tool would be to give you a thorough knowledge of geometry, and fill a volume. I will, however, give some of the more common uses:
1. In sawing across a board, if you wish to have the cut true and even, you must use the square. One edge is, of course, already planed, and from this all your lines are drawn. You wish, we will suppose, to saw three inches from the end of your board; lay the thick or handle part of the square close against the even edge of the board, three inches from the end; you will find that the blade lies flat across, the board at a right angle with the edge, and a pencil line drawn close to the blade will be a guide for cutting.
2. To test the evenness of the end of a board which you have been trimming with a block-plane: Apply the square to the side and edge of the board; if the work is true, the blade will be level with the end of the board; if uneven, the defect is quickly seen.
3. It is well to test your square itself; thus: Lay your square snug against a straight edge with the handle to the left; draw a line where the edge of the blade comes: then reverse the square, having the handle to the right; draw a similar line: if the square is true the lines will coincide; if they diverge ever so little the square is imperfect, and you should buy another.
4. In planing the edge of a board, put the handle of the square against the face of the board; the blade will then go across the edge, and you can soon see if it is even; i.e., at right angles with the face of the board.
Hammering a nail seems a very simple thing, but there’s a right way and a wrong way to do that, as you’ll find for yourself after you’ve split two or three bits of work; but you might as well learn the right way at first.
If you look at a nail of any size, from a brad to a twenty-penny spike, you will find that the sides are parallel and straight, and two are wedge-shape or sloping; also one of the straight sides is finished smooth, the other is rough. A nail is virtually a wedge. Now the principle of the wedge is to split things when the wedge goes with the grain, as when you split a board with an axe or hatchet; for an axe is a wedge, as you will see if you think about it.
If, then, your nail is put in wedge-fashion with the grain, ten to one the second good tap with your hammer splits the board; if, however, you turn the nail the other way, so the wedge side is across the grain, and the straight side with the grain, the nail is held firm by the grain pressing against the wedge, and the board doesn’t split. This is the reason that fine work is done with brads better than with tacks, for tacks are wedge-shaped on all sides, and in driving them if the wood is thin it is very apt to split.
Always start a nail in the direction you mean to have it go, and don’t depend on straightening it afterwards. If, however, it gets a wrong slant, don’t bend it back with your fingers, nor hit it a knock sideway with your hammer which will likely enough break the nail short off; but with every regular stroke of your hammer give an inclination in the right way, and it will get there.
Don’t hold on to the nail too long; in soft wood the second hammer tap ought to find the nail firm enough to stay. Don’t make the first or the second hammer stroke a long hard one; if you do, likely as not you’ll mash your fingers. The first tap should be light and short; get the swing gradually, a few inches first, adding a few inches more with each stroke; by the time you want full force to drive the nail home, you’ll find you can’t hit anywhere but on the head of the nail. This is something that practise alone can make you perfect in. If you watch a good building-carpenter, it seems as if he threw the nail into place with one hand and hit it on the way.
Don’t think you must look at each nail in order to place it right. Your eyes must be in your finger tips; the smooth side goes with the grain.
Always keep the different sizes of nails separate; then you won’t be bothered by finding the wrong nail in your fingers when you are in the midst of a job.
In using chisels and gouges never strike with a hammer, but always with a wooden mallet; the hammer splits the handles.
In most chisel work it is better to put the bevel edge to the line you wish to cut until you have cut out most of the wood, then finish with the other edge and the pressure of your hand instead of the mallet.
It will be easier to explain the use of the other tools as we come to them in construction.
