Examine the teeth (Fig. 652) and you will see that they are pointed and sharp, somewhat like the point of your knife, and that they cut across the fibres much the same as your knife does when you hold it upright and draw it across a board.

You will notice, also, that the teeth are alternately bent outwards,—one tooth being bent out to one side, the next to the other side,—this spreading of the teeth (which is called the "set") making the saw wider at the points of the teeth than elsewhere. You will also notice that the sharp cutting edge of each tooth is on the outside. This set, and the way the teeth are sharpened, makes the cut wider than the thickness of the blade, thus giving the saw "clearance" and enabling it to slip back and forth easily and without "binding" (Fig. 653). As a practical matter of fact, however, it is nothing uncommon for a saw to bind in the cut, either from not sawing straight or from the wood closing on the saw (see Fig. 695). The teeth not only cut or break off the fibres in parallel lines at the points of the teeth, but also tear off and remove the bits of wood (i.e., the sawdust) between these parallel cuts.

The degree to which the teeth are set and the number of teeth to the inch depend upon the use to which the saw is to be put and the kind of wood to be used. Of course the finer the teeth the smoother the cut. Cross-cut saws are usually sharpened differently for soft and for hard wood, but little set being required for the latter, while the former needs a wider set to give the blade clearance, because the fibres of the looser-textured soft wood are bent aside by the tearing action of the saw teeth and are not so cleanly cut off as in the hard wood.

We have examined the teeth of the cross-cut saw and have seen that they cut across the grain of the wood very much as the point and edge of a knife, and that the fibres, being cut or broken or torn off in fine pieces, are removed from the kerf by the teeth. Now to saw in the direction of the grain, instead of across it, we use a saw based on a different principle. As we used little knives to cut across the grain, so we use little chisels to cut with the grain. Look at the teeth of the ripping-saw and you will see that they are little chisels sharp only at the end (Fig. 654), though not as acute as chisels for obvious reasons. These sharp ends, which are square (Fig. 655, showing set) or may be oblique, cut or tear off the fibres, and the front edges of the teeth push the pieces out of the cut. The teeth of the cross-cut saw are filed so that the front cutting-edge is drawn across the wood in the most effective way, much as you would draw the knife-point across, while the teeth of the ripping-saw are pointed forward at a more acute angle so that the cutting-edge is pushed through the wood, somewhat as you push a chisel.

The ripping-saw cuts only on the down stroke. It is not suitable for use directly across the grain, as it tears the fibres when pushed across them much more than the cross-cut saw. The ripping-saw usually has larger teeth than the cross-cut saw. From 5½ to 8 points to the inch will do for your work. The ripping-saw usually cuts best when held slanting rather than at right angles with the board (Fig. 656), as you can easily understand when you think how a chisel works best in paring at the end of a board.

If the cut closes up after the saw so as to "bind" it, drive a wedge (or even a screw-driver or chisel) into the crack so as to open it enough for the saw to work freely. Binding of the saw from this cause is very common in making long cuts. When you come to a hard knot in splitting you can sometimes gain by taking the cross-cut saw to cut through it.

You will probably get most of your splitting done at a mill and will not have to depend on hand ripping-saws so much as your grandfathers did.

The back-saw should have, for your use, from 10 to 16 teeth to the inch and be perhaps 12 inches long. The blade is very thin to insure a finer and more accurate cut than can be made with the common saw, and therefore requires care in using. It has a back (whence the name) made of a thin piece of brass or iron put on so as to give the blade the necessary firmness.

This is an exceedingly useful tool, with which and a common panel saw you can do a great deal of work without any other. The back-saw must be used with care, for the blade is so thin that a little wrenching will spring it out of shape in spite of the strengthening back.

In the compass-saw the blade is very narrow, being about one inch at the broadest part and diminishing gradually to about a quarter of an inch at the other end. It is about fifteen inches long and is employed in cutting curved forms. As the blade is narrow and tapers towards the back and the teeth have a wide set it will cut a small circle. Notice that the teeth of the compass-saw are a sort of a compromise between those of the ripping and cross-cut saws, which enables them to cut freely either way of the grain, as is of course necessary in sawing curves.

The turning- or bow-saw is much better for any work with which the bow will not interfere, and is a very useful tool at times. Get one with handles which turn so that the blade can be turned to saw at an angle with the frame. You will need a few extra blades of different widths. The main thing to be borne in mind is to make the cut square with the surface. It is easier to follow the line than to secure a cut at right angles to the surface.

The keyhole-saw, which is even smaller than the compass-saw, is used for cutting quicker curves, as for a keyhole. It has a handle like that of a chisel, with a slot cut through from end to end. There is a screw on one side, so that the blade may be fixed at any length, according to the size of the hole to be cut. A good kind, which can be used for both compass-and keyhole-saws, has a handle into which various blades can be fitted.

Compass-and keyhole-saws are difficult for beginners to use without bending, twisting, or breaking their thin and narrow blades. Most of your curved sawing can be done better with a turning-saw or at a mill by a band- or jig-saw. If done at the mill, have a piece of waste wood put on the under side to prevent the burr, or ragged edge, left by the sawing.

A common way to test saws, when buying, is to take the handle in one hand and bend the point of the saw around in a curve sideways and then let the blade spring back, which it should do without being permanently bent or sprung.

Do not saw from one side of the line. Have your eyes above the line so that you can look on both sides of the saw (Fig. 657). This will help you to keep the saw-blade at right angles with the surface of the wood.

Hold the saw firmly with the forefinger pressed against the side of the handle to help guide and steady it (Fig. 657).

Having placed the saw just at the outside edge of the line and on the farther side of the piece, seize the wood with the left hand and hold the thumb against the blade (above the teeth) to help start the cut in the right place (Fig. 658). Aside from the danger of the saw jumping and damaging the wood unless guided by the thumb, it is liable to cut your left hand.

You can make a little notch with the knife or chisel on the outside of the line, to help start the saw, in the case of nice work, if you wish. Cut straight in just on the line and then make a sloping cut to meet this from outside the line (Fig. 659). First draw the saw gently backwards, guiding it by the thumb, with as little pressure on the wood as possible until you see that the cut is started right, then push it gently forward, and after a few easy strokes in this way to get the cut started right, keep on with long, steady strokes, but not long enough so that the end of the saw enters the kerf, lest it catch and the saw buckle. The saw should cut most on the downward motion, not on the up stroke.

With a sharp saw, there is nothing gained by bearing down heavily on the teeth, which may spring the saw and make crooked work. Rather let the saw run of itself with an easy, light stroke, guiding it carefully, and not letting it press on the wood on the up stroke. The more hastily and furiously you saw the poorer the result will probably be.

When you begin to run off the line, as you will be pretty sure to do, twist the saw a little with the wrist as you go on, which will bring it back to the line, because of the kerf being wider than the thickness of the saw-blade.

Beginners are apt to bend the saw over to one side. You can tell whether it is cutting at right angles with the face of the board by testing with the try-square as shown in Fig. 660. Such a test as this is, however, too inconvenient for ordinary practical work and you should learn as quickly as you can to hold the saw-blade correctly.

At the end of the cut, as at the beginning, saw gently with quick, light strokes, and hold the piece which is being cut off with the left hand, lest it break off and splinter one of the two pieces.

If the saw "binds" or does not work easily, you can for your rougher work put a little tallow, butter, lard, or lubricating oil on the blade, but beware of doing this for your nice work, or it will deface it when done. If the binding is caused by the springing together of the wood (Fig. 695) the crack should be wedged open.

Do not get into the habit of sawing a little way outside of the line and then trimming off the superfluous wood with your knife or a chisel. That is not a good way to learn to saw by a line. Try your best to make the cut where it should be (even if you do make mistakes for a good while) and thus get into the habit of doing it right without having to rely on any other tool than the saw.

Many pieces of wood can better be screwed in the vise for sawing instead of being laid on the horses, and this position is often preferable. In this case you grasp the wood with the left hand and use the saw as already described. (See Sharpening).

Saw-Filing.—See Sharpening.

Sawing.—See Saw.

Saw-Set.—Various contrivances can be bought for setting saw teeth. When you get to the point of needing one you can easily find a variety from which to select.

Scraper.—The scraper is made of saw-blade steel (frequently from an old saw) and may be of any shape or size to suit the work required of it. A common form for scraping flat surfaces is rectangular like a postal-card, and a good size is from 2" × 4" to 3" × 5".

A piece of glass makes a good scraper for almost every purpose except where a flat, true surface is required. It is good to smooth the handle of a paddle, for instance, but not good for scraping the top of a nice table. For many rounded surfaces glass is fully as good as a steel scraper, but for general use the latter is much better. The following directions may be of use when you wish to break glass to use for a scraper: "Take the back of a knife, or the smooth, straight edge of any piece of iron fixed with tolerable firmness for a moment, then, taking the piece of glass in both hands, rest its edge midway between them on the edge of the iron; let the upper edge of the glass lean from you, and push it gently along the iron, so as slightly to indent the edge of the glass; then, reversing its position so as to make it lean towards you, draw it smartly along the iron, and you will find it separated by a clean fracture directly across, forming a line more or less curved, and leaving one edge of the glass much sharper than the other. By a little practice, and by pressing a little more with one hand than the other, almost any curvature that the work to be done may require may be achieved" (Lord and Baines, Shifts and Expedients of Camp Life).

The edge of the scraper is turned over so as to form a sort of hooked edge or angle (Fig. 661), which when pushed over the surface scrapes off thin shavings. To smooth a flat surface the scraper can be held with both hands, between the fingers and thumb (Fig. 662), and pushed along in the direction towards which it is inclined. Sometimes one end of the scraper is held between the thumb and fingers of the left hand and the palm of the right hand applied below to push the tool along. As a rule scrape with the grain, and it is often advantageous to hold the scraper obliquely to the grain when pushing it forward. In case of some crooked and twisted grain you will find it best to scrape in any and in all directions.

You can make scrapers yourself by filing and grinding pieces of old saw-blades. It is very convenient to have a number of them with edges of various degrees of curvature (both convex and concave), but these you can make as you need them. A scraper is sometimes set in a stock and guided by handles like those of a spoke-shave, and sometimes set in a stock like a plane and used in the same manner. A scraper of the latter sort is often useful to assist in keeping the surface true when scraping, as its flat sole prevents its following all the undulations of the surface as readily as the hand-scraper, with which one is apt to make depressions by scraping too much in some particular spot. But so far as smoothing the surface goes there is nothing better than the common hand-scraper or so easily taken care of. For sharpening the scraper, see Sharpening.

In many large places you can get your wood for nice work scraped to a satin-like finish by a machine made for the purpose, but this is hardly worth while for ordinary work. You can also have it smoothed very nicely by sandpapering machines, but this is not advisable if there is to be any cutting of the wood afterwards, as the grit left in the pores of the wood will quickly take the keen edge from your tools.

The best test for smoothness alone is to run the fingers over the surface with a light touch. Great acuteness of touch can be acquired in this way. Any experienced wood-worker can at once detect inequalities with his fingers that he could not possibly see. Irregularities in curves can be detected in the same way.

Bead cutters or scrapers and reed scrapers and fluters can be bought of various patterns. You will hardly need to buy anything of the sort for some time, as you can make one when required. See Beading.

Scratch-Awl.—See Awl.

Screw-Driver.—The screw-driver is too familiar to need description, but in buying one see that the end is shaped like either of those shown in Fig. 663 and not as shown in Fig. 664. Cheap screw-drivers are often made in the latter way. If ground with a short bevel (Fig. 664) it will bear only on the top of the slot in the screw and will be all the time slipping out, on the principle of the inclined plane, while if the sides are parallel or concaved slightly the end will remain at the bottom of the nick of the screw. This is also a help in extracting screws, as it saves the need of pressing against the screw so hard to keep the screw-driver from slipping out of the slot. It is well to have screw-drivers of different sizes, as it is difficult and often impossible to use a screw-driver with an edge much too large or too small.

Remember that a long screw-driver is always preferable to a short one, except where lack of space makes a short one necessary. The reason for this is in the fact that in using the screw-driver you do not, as a practical matter, keep it exactly in the line of the screw, but keep wobbling it round more or less, which gives a leverage in the form of a crank-like action as you turn the handle. The longer the screw-driver the larger the circle or wobbling curve you describe with your hand and the greater the leverage (Fig. 665).

A screw-driver to be turned by the bit-brace is very useful for driving screws rapidly and with force, on account of the greater leverage gained by using the brace instead of the common handle. This is particularly useful where they need to be driven in very hard or when tight screws have to be loosened. It also saves much time when many screws are to be used. It is not advisable to buy automatic screw-drivers. They work satisfactorily for light work, but are not suitable for such wrenching and straining as your screw-drivers are liable to be subjected to. You want screw-drivers to which you can apply all your strength. See Screws.

Screws.—There are many kinds of screws. You will use the common wood-screws for most of your work. These are either flat-headed or round-headed, and of steel (either bright or blue or bronzed or nickled) or of brass. When others are required they will be mentioned. It is doubtful economy to buy second-hand or waste screws, but a pound or two of "mixed" screws, which you can get at any hardware store, will be very useful when you want some odd screw for some special purpose. Many of the screws in the "mixed" lots, which are sold very cheap, are defective, but you can often find among them just the peculiar screw you need, and so save time and money.

Nails are often used where it would be better to use screws, which will, as a rule, hold the pieces more securely. When work becomes loose, screws can be tightened, while nails usually have to be redriven.

To make a screw drive easily, rub the point on a piece of common soap. Oil is objectionable for nice work on account of the spot made by it. If screws are to be used in places where they may rust, it is a good plan to warm them slightly and then dip them in melted tallow or lard. They can also be inserted and removed more easily for this treatment. Try to keep the screw-driver from slipping from the slot of the screw (see Screw-driver).

In boring holes for screws, considerable discretion must be used. The hole in the outer piece (the one nearer the head of the screw) should be large enough to allow the screw to slip through freely—that is, you should not screw it into both pieces, but only the inner one, the screw acting somewhat in the nature of a clamp to bind the outer piece to the inner by pinching it tight between the screw-head and the inner piece (Fig. 666). How much of a hole to bore in the piece into which the point of the screw enters depends on circumstances. The stouter the screw the less hole required. The softer and larger the piece and the farther from the edge the less hole required. If the piece is small or liable to split, the hole must be carefully made—the more carefully in proportion to the slenderness of the screw, as a slim screw is liable to twist off in hard wood unless a sufficient hole is provided. Brass screws are very apt to do this, and much care must be used, particularly with slender ones in hard wood. If the hole is a bit too large, they will not hold. If a trifle too small, they will twist off, which is very annoying, especially in such cases as hinge-screws, for instance, where the place for the screws cannot well be changed. The hole should be somewhat smaller than the diameter of the screw. In good-sized pieces of soft wood there is frequently no need of any hole.

In rough work, especially in soft wood, the screws may be pounded part way with the hammer, driving them home with the screw-driver. Some theoretical workman will be quite sure to tell you never to do such a thing as that, so be sure to understand what is meant. Theoretically there may be some loss of holding power by that process, but practically the screws will hold just as well for the cases in which you are advised to do that way. Judgment must be used about all such things and theories are only of value when used by the light of common-sense. For example, if you are screwing the top on a mahogany table or framing a nice boat never think of using a hammer to start your screws, but if you are putting cleats on an old shed door or screwing up a packing-case do not spend an hour and a lot of strength driving screws all the way with a screw-driver when you can do the work in half an hour by driving the screws three quarters of the way in with the hammer. Good practical workmen are just as certain to use the hammer in such cases as they are careful not to use it for nice work or where the full holding power of the screw is needed.

Flat-headed screws almost always should be countersunk (see Countersink), for neatness if for no other reason, and in hard wood you should cut the depression for the head of the screw with the regular countersink made for the purpose. This should be done for nice work in soft wood where a good surface is required, but for common work in soft wood there is no need, as a rule, for the head of the screw will sink itself easily until flush with the surface.

If a screw hole requires to be moved a little, but not far enough so that a new hole can be bored without the bit slipping into the old hole, plug the old hole with a wooden pin dipped in glue, and when dry bore the new hole where required.

See Screw-driver.

Scribing.—Compasses are often used for scribing a line parallel to another line or surface, whether regular or irregular, in places where the gauge cannot be used. Suppose, for instance, you wish to cut the edge of a board to fit the undulating surface shown in Fig. 667. Run the compasses along with one point on the surface and the other making a mark on the board, and the line on the board will be parallel with the surface.

Another example is that of making a table, bench, chair, horse, or any four-legged object stand evenly. If it stands on three legs, which is a common fault and likely to occur in your first attempts, do not hastily saw one leg shorter by guess, and, making it too short, saw another and so on until it stands firmly, when the top will probably be all out of level. If there is any true surface on which you can stand the article (right side up), you can level the top by wedging under the legs until the corners of the top are equally distant from the surface on which the object stands. Then setting the compasses at a distance equal to that at which the end of the shortest leg is raised (Fig. 668), scribe around the other legs, which can then be cut off.[50]

See also Winding-Sticks and Marking.

Setting Saws.—See Sharpening.

Sharpening.—Before attempting to sharpen your tools yourself it would be well to read the advice given on page 22 under Care of Tools.

The general process of sharpening edged tools is first to grind them to as keen an edge as possible on the grindstone, or the emery-wheel, then to smooth down the coarse edge left by the grindstone by rubbing on a fine stone with oil or water, and finally stropping on leather. The grindstone must be kept wet while grinding or the heat caused by the friction of the tool on the dry stone will ruin the temper of the steel. Besides, the water carries off the waste particles of stone and steel. Stand on the side towards which the top of the stone turns. The tool can be ground with the stone turning from you, and, in fact, this usually seems the natural way to a novice, but it is usually more difficult to grind uniformly in that way and too thin an edge (a "wire-edge," ragged but not sharp) is apt to be produced, the removal of which is difficult without further damaging the edge and delaying the final sharpening.

To grind the point of a knife, it can be moved back and forth lengthways with a curving motion, while resting flat on the grindstone, and to grind the straight part of the blade, it can be allowed to bear very slightly harder near the edge of the stone than elsewhere, as it is passed back and forth.

To grind a chisel, grasp the handle with the right hand, hold the blade in the left hand with the fingers uppermost and near the cutting-edge. The arms and wrists should be kept as rigid as possible, the former at the sides of the body, so that the tool may be held firmly against the motion of the stone. Lay the chisel with slight pressure quite flatly on the stone and then raise the handle until the bevel touches the stone. As you grind keep moving the tool slowly back and forth across the stone, which helps keep the edge of the tool straight and prevents the stone being worn away too much in one place. Use plenty of water.

The common way of holding the tool on the stone is the one just described, but it can also be held at right angles to this position, so that, in the case of a chisel, for instance, the grinding action of the stone instead of being from the edge toward the handle is from side to side of the blade. The tool is ground quicker and easier by this means, and it is a good way to reduce the edge to shape, finishing the grinding by the regular method.

You will see that the curvature of the stone will tend to give the bevel a slight curve, in whatever position the tool is held, which is advantageous in the common way of grinding. When held so that the stone grinds from side to side of the blade the tool must be continually turned a little in the hand so that each part of the edge will bear in turn on the stone, as, the tool edge being flat, and the surface of the stone rounding, the tool would otherwise be ground hollowing. It is harder to hold the tool in this way, however, without its slipping or making nicks or grooves in the stone, and you had best learn to grind in the ordinary manner.

Try to grind squarely across the chisel—that is, to have the cutting-edge at right angles to the lengthways edge of the tool. Apply the square at intervals to test the accuracy of the grinding.

The angle for grinding the bevel of such tools as the chisel is about twenty-five degrees, but when used for very hard wood the angle should be slightly greater, or the edge may be broken.

Do all the grinding on the bevel. Do not apply the flat side of the tool to the grindstone. Any slight burr or turning over of the edge on the flat side should be taken off by the oil-stone.

If the edge is badly nicked or broken, you can first straighten or grind it down roughly on the side of the stone or by holding it nearly at right angles to the stone—but with the latter turning the other way—before grinding in the regular way.

To tell when the tool is ground sufficiently, hold the edge in front of you toward the light. If the edge can be seen as a bright shining line it is a sign that the tool is dull. It will not be sharp until this bright line has been removed, and the edge has become invisible, for a really keen edge cannot be seen by the naked eye. Bear this in mind, as it is the final test and the simplest way to tell when to stop grinding.

In grinding on a grindstone and in rubbing on an oil-stone, the great difficulty is to keep the same angle between the tool and the stone, as the natural tendency in moving the tool is to rock it back and forth and thus alter the angle between the blade and the stone. An arrangement can be bought which preserves the desired angle without effort on the part of the grinder. A little ingenuity will enable you to rig up a guide or gauge with a piece of board which will enable you to replace the tool on the grindstone at the same angle.

The plane-iron is sharpened in the same way as the chisel, only, being wider than most of the chisels you are likely to use, it requires more care to sharpen. The plane-irons can be ground to a somewhat more acute angle than the chisels, although the jack-plane, which is used for rough work, may require more strength at the edge.

In rubbing the edge upon the oil-stone, do not attempt to smooth down the whole bevel made by the grindstone, but first lay the tool lightly on the stone as shown in Fig. 670a, then raise the handle until the upper part of the bevel is very slightly raised,—barely enough to clear the stone (Fig. 670b),—and then proceed with the whetting, thus making a second or little bevel at the edge (Fig. 671).

The tool must be moved back and forth very steadily or instead of a second bevel the whole edge will be rounded (Fig. 672) and will not have the requisite keenness. The angle of this second bevel is usually about ten degrees greater than the long bevel, or thirty-five degrees, although the angles of sharpening should be varied slightly according to the hardness of the wood and the kind of work to be done; but where you have only few tools and must use them for all kinds of work you cannot always, as a practical matter, pay much regard to such variations, as of course you cannot keep regrinding your tools every time you begin on a new piece of wood. Just how acute to make the edge you must learn by experience, according to the conditions of your work. An edge suitable for delicate work in white-pine would be immediately ruined if used upon lignum-vitæ.

Any little wire edge which is produced on the flat side by the process of rubbing on the oil-stone can be removed by drawing the flat side of the iron over the stone once, but be sure that you do not raise the handle at all, as the slightest bevel on the flat side of the edge will spoil it. After the tool has been sharpened a good many times on the oil-stone this smaller bevel (the oil-stone bevel, so to speak) will become so wide that it is a waste of time and strength to rub it down. The chisel must then be reground and a new bevel made on the oil-stone.

It is a good plan to have a separate stone or "slip" for the outside bevel of gouges, because it is so hard to avoid rubbing hollows in the stone, which injures it for the other tools. Care must be taken also with very narrow or pointed tools lest the stone be grooved or nicked. Gouges can be rubbed at right angles with the stone, rolling the tool with the left hand, or by the use of a slip they can be rubbed as described below. For rubbing gouges on the inside, i.e., on the concave surface, rounded pieces of stone, called "slips," are used. These can be bought of various sizes and shapes to fit the various curves. Do not think, however, that you must try to find a slip that will fit each gouge as exactly as if it had been shaped by the gouge itself. The curve of the slip may be a little "quicker" or sharper than that of the tool, but must not be flatter or of course it cannot be made to bear on all parts of the curve.

In rubbing with the slip, hold the tool upright in the hand and rub the slip up and down, moving the slip and not the tool. If you rest the tool against the bench, it will steady it and also avoid any probability of your finger slipping on to the edge. The more common "outside" gouges are not rubbed on the inside, except the merest touch of the slip to remove any wire edge or burr. The draw-knife is also rubbed with a flat slip, in the same manner, resting it on the bench.

In rubbing the knife on the oil-stone give it a circular motion rather than simply back and forth, particularly for the point. The straight part can be allowed to bear a little more heavily near the edge of the stone as it is passed back and forth.

It is much the best way to sharpen tools frequently, as soon as they begin to get dull, when they will require but little rubbing on the stone, rather than to let them get into such condition that it is a long and hard job to whet them; and of course the more careful you are to keep them sharp, the better work you will do.

To test the sharpness of your tools, cut across the grain of a piece of soft pine wood. If the cut is clean and smooth, the tools are sharp, but if the cut is rough or the wood torn, further sharpening is needed. The reason for using soft wood, which at first thought might not seem to require as keen an edge as hard wood, is because the fibrous structure of the soft wood, being more yielding, offers less resistance to the tool and so is torn or crushed apart except by a very keen edge, while the firmer structure of the hard wood can be cut smoothly by a tool which would tear the soft wood. The difference is somewhat like that between cutting a fresh loaf of bread or cake and a stale one.

The edge left by the oil-stone can be improved by stropping on a piece of leather on which a little paste of lard and emery or some similar composition has been spread. This is better than to strop knives and other tools on your boots. Any piece of leather such as barbers use, or even a piece from an old boot, will answer. For flat edges see that the strop rests on a flat surface, so as not to tend to round the edge, as it may do if held carelessly in the hand. See Oil-stone and Strop.

Saw Filing is particularly hard for boys and amateurs to do satisfactorily and you are advised not to undertake it until you have become quite familiar with the use of tools, for it does not need to be done very often, costs but little, and there are very few places where you cannot get it done.

It is not difficult to understand the theory of setting and filing saw teeth, but to fix a saw in really good shape is hard for an amateur,—and for that matter you will find but a small proportion of good workmen who are experts in saw filing. Even in very small villages there is almost always some mechanic who has the knack of putting saws in order better than anyone else and who therefore makes quite a business of such work and people bring their saws to him from all the country round, even though they may be able to fix them tolerably well themselves, so great is the advantage in the quality of the work and the saving of time in having a saw in perfect condition. You had best do the same, and have your saws fixed whenever they get dull. The expense is but slight, and there is nothing that will conduce more to good work, and to your own success and satisfaction, than to have your tools in first-rate working order.

When you get to the point of filing and setting your saws you are advised to take a lesson from a good saw-filer. There are few persons so situated that they cannot do this, or at least watch someone go through the process, and thus learn much more readily than by reading about the process in a book. In fact, it is one of those things that it is so hard to learn from a book that merely a few remarks on the subject are given here.

The saw is firmly fastened in a saw-clamp, expressly for the purpose, so that it will not shake or rattle. The teeth are "jointed," or reduced to the same level, by lightly passing the flat side of a file over their points, lengthways of the saw. The saw can also be jointed along the sides after filing, but this is frequently omitted.

For a cross-cutting saw the file (a triangular saw-file) is held at an angle with the blade depending upon the particular form of tooth adopted, as you will see by examination. The handle being grasped in the right hand, the point of the file should be held between the thumb and forefinger of the left hand (Fig. 526). The file must be pushed across with an even, straight stroke, without any rocking or up and down motion, pressure being applied only on the forward or pushing stroke, the tool being drawn back very lightly or lifted entirely on the back stroke. The filing is begun at one end of the saw, filing only the teeth which bend away from you (i.e., every alternate tooth), carefully keeping the file at the proper angle, pressing only on the tooth you are filing, but keeping the tool lightly touching the adjacent tooth, and making allowance for the fact that when you file the alternate set the passing file will take off a little from the teeth first filed. The saw is then turned around and the process repeated with the other teeth. If you look lengthways along the edge of a panel-saw that has been properly filed and set, an angular trough or groove will be seen along the whole length, so that you can slide a needle along in it from one end of the saw to the other.

The ripping-saw is usually filed squarely across the saw (at right-angles to the blade), as you will see at once on examination of the teeth (Figs. 654 and 655), but sometimes at a more acute angle.

The teeth are set by bending every other tooth outward, first setting those on one side and then those on the other. You should do this with some one of the various adjustable tooth-setting contrivances sold for the purpose, as it requires a skilled workman to set teeth in any other way, and any attempt on your part to do so without some instrument adjusted to the purpose will probably result in damaging the saw.

For soft and loose-fibred wood more set is needed than for hard wood, because the fibres, which are quite cleanly cut or broken in the hard wood, in the more yielding soft wood are bent aside by the teeth to close in upon the blade with considerable binding force; and less set is required by fine work than for coarse. The angles and points of saw teeth can be more acute for soft than for hard wood.

To sharpen the scraper you must have a sharpener or burnisher. The edge of a chisel or any piece of very hard steel can be used after a fashion, but it is better to have a regular tool for the purpose, which can be made easily from an old three-cornered file, such as is used for filing saws, by grinding off the teeth and slightly rounding the angles on the grindstone until the whole tool is smooth. Two opposite edges of the scraper are ground or filed and the edge then turned over by the burnisher. Some workmen grind the edges with an obtuse bevel and use only one angle of each edge. Others grind the edges square and use both angles of each edge. The bevel gives a slightly keener scraping edge than to grind the steel square, but it requires more frequent sharpening and the squared edge turned over on both sides is likely to be more satisfactory.

First grind or file the two opposite edges squarely across and slightly round each corner to prevent scratching the wood. If there is a burr at the edge it can be removed by rubbing the scraper lightly on the oil-stone, but this is advisable only for final scraping of very fine work. Having thus got the edge at right angles and smooth, lay the scraper flat on its side near the edge of the bench and rub the burnisher back and forth a few times in the position shown in Fig. 673, which is almost flat on the scraper. This rubbing bends a little of the steel over the edge. Do this on each opposite edge of the two sides, giving four edges thus curled over. Next, holding the scraper as shown in Fig. 674, draw the burnisher with a firm, even stroke, once or twice, lengthways of the edge, as shown. The scraper can be laid flat on the bench, if preferred, slightly projecting over the edge. Notice that the tool should be drawn with a slightly end to end motion, as shown, which helps turn the edge. This turns a fine scraping edge, which will take off shavings. All four edges are treated in the same way. After one edge gets dull, use another. When all four are dull, resharpen with the burnisher as before, without grinding or filing the edge. This can be done a few times, but soon the edges will get worn off and rounded, and the scraper then needs refiling.

Shellac.—See Finishing.

Shell-Bit.—See Bits.

Shelves.—Examples of shelves fitted permanently into place are given in Chapter X. (on Furniture). Removable shelves can most easily be fitted to rest on cleats screwed to the sides of the space, but this arrangement does not always look very well and the position of the shelves cannot be changed so readily as by using screw-eyes driven into the sides under the shelves (Fig. 675), recesses of the right shape being cut on the under side of the shelves so that the screw-eyes will be sunk and not be conspicuous. The position of the shelves can quickly be changed by screwing the supports higher or lower as may be required. Pins and other contrivances to fit in a series of holes can be bought for this purpose. A common way to adjust shelves is shown in Fig. 676. The construction is obvious. The vertical strips can be laid on edge side by side, clamped together, and the notches laid out and cut as if there were but one piece. Where a circular saw is available the notches are cut on the side of a narrow piece of board which is then sawed into the desired strips or "ratchets."

Shooting-Board.—The shooting-board is very useful for jointing edges, particularly for short, thin stock. The carpenter or cabinet-maker will make you one for a moderate price, or you can make one yourself as soon as you become a good enough workman (see page 93).