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قراءة كتاب Manual Training Toys for the Boy's Workshop
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crossing at the center.
The teeth of a rip-saw are like so many little chisels set in a row; they pare the wood away. The teeth of a crosscut-saw are like knife points, they score two lines, and the wood breaks off between them. Large sawing should be done on a saw-horse so that the worker is over his work. If it is necessary to hold work in the vise to rip it, hold it slanting, so that the handle of the saw leads the line, as it naturally does when the work is on a saw-horse.
The back-saw, tho a crosscut-saw, may be used in any direction of the grain.
Any saw should be in motion when it touches the wood it is to cut. To guide it to the right place, a workman lets his thumb touch the saw just above the teeth, the hand resting firmly on the wood. A little notch, cut in the edge right to the line where the saw is to cut, will help a beginner to start accurately. Saws are rapid tools, and it pays to go slowly enough with them to do accurate work. Plan the work so as to make as few cuts as possible.
Turning-saws are best used so that the cutting is done on the pull stroke, keeping the two hands near together. When one handle is turned, the other must be turned equally.
Generally being in a hurry to get work done, boys are apt to take big shavings with a plane. This results in rough work. Fine shavings are better. If the plane is allowed to rest level on the work, it will find the high places without continual adjusting. The first two inches of a stroke are the hardest to plane; to plane these, press harder on the forward end of the plane. Start the plane level. Usually it is best to keep the plane straight, or nearly so, in the direction of the push.
The block-plane is properly used to plane the end of wood. (See page 12 on Holding Work.) On other small surfaces, however, it is often more convenient than a large plane.
Auger-bits are numbered by the number of sixteenths in the diameter of the hole they bore, e. g. No. 4 bores a 4/16" hole. Gimlet-bits are numbered by thirty-seconds.
Whenever boring with an auger-bit, stop as soon as the spur pricks thru the other side, turn the work over, start the spur in the little hole it made, and finish boring. It will always split the wood, if the bit is allowed to go way thru. It is difficult to bore a hole straight thru a piece of wood, because to tell whether the bit is held straight when starting the hole, one must look at it from two directions. If someone else can stand a quarter circle away from the worker and watch the bit, that is the best help; otherwise, the worker himself must hold the brace steady while he walks around a quarter circle and judges whether the bit is straight. Care should be taken to hold the work level in the vise.
The words, "nail," "brad," and "nailing" are used somewhat interchangeably in this book; "nailing" may mean driving a brad. Brads have smaller, thicker heads, nails have larger, flat heads.
To drive a nail straight, start it straight. The hole cannot be straightened by bending the nail so that it looks straight after it is partly driven. Many gentle blows with the hammer will often drive a nail where heavy blows would fail. The fingers pinching the nail often prevent its bending. If possible, keep nails away from the corners of boards. Several nails joining two boards hold them stronger if the nails are driven at different angles. Nails are usually "set," that is, the heads are driven with a nail-set below the surface. They must always be set below surfaces which are to be planed. It is often wise not to drive the first nail or two way in until the work is examined. In withdrawing nails, a block under the hammer will often aid greatly, and also protect the surface of the work.
Screws usually need holes properly bored to receive them; a large hole first, the size of the screw above the threads, a small hole next, the size at the roots of the threads (in hard wood somewhat larger), and a place for the head made with a countersink. Usually the screw should slip easily thru the first piece of wood and be tight in the second. The screwdriver should always be held in the line that the screw is going, and it ought fairly to fit the slot in the head. In hard wood, one must be careful not to twist screws off, especially brass screws, which are easily broken.
A beginner often wonders why things stick to his fingers instead of to their proper places; it is because he has a little glue on his fingers and usually a lot on the article; therefore, don't use too much glue. It is best, especially in holes and their pegs, to put glue on both surfaces of contact. Good glue will hold two surfaces, making good contact, stronger than the wood. Wipe off excess glue as soon as possible, using hot water for hot glue. Much labor is thus saved. Allow glue plenty of time to become dry. The moisture has to work its way thru the wood itself, and this takes hours; six to ten hours is not too long.
Sandpaper varies in coarseness from No. 00 to No. 3, every sheet being stamped. It should not be used on a given piece until all work with edge tools is finished. The particles of sand left in the surface would quickly dull an edge tool. When using sandpaper on flat surfaces, wrap it closely about a rectangular block of wood. Try to keep all corners as sharp as they are left by the edge tools so that there will be a crispness of appearance which always marks good workmanship. Often the same care in holding work while sandpapering it must be taken as was taken when shaping it. Always sandpaper with, or lengthwise the grain.
Sticks that are planed nearly to size can be made round and smooth by driving them thru a hole in a block of hard wood or iron; such sticks are called dowels. Two holes may be used if the second is only a little smaller than the first. Drive gently with a mallet rather than with a hammer. In many of the models in this book such dowels are used. Dowels (made by a different process, however,) can often be bought at hardware stores.
For ease in making small holes, a hand-drill is essential. For some holes a headless nail will answer. To make better drills, break a needle, a knitting-needle, umbrella rib, or other piece of hard wire to suitable length; on a grindstone, flatten it near the point on two sides; then, putting it in the chuck of the hand-drill, try to hold it on the grindstone at the proper angle to form the two cutting edges; or it may be held against the edge of the bench and sharpened with an oilstone resting on top of the bench. Very convenient long drills can be thus made of knitting-needles.
To work with dull tools is altogether unsatisfactory. A boy should learn to sharpen his own edge tools. To grind a good bevel on a