MAINTENANCE OF TOOLS

Contents:

• CUTTING ANGLES
• SHARPENING PLANE IRONS AND CHISELS
  Angle and shape of the cutting edge / How to grind plane irons and chisels on the grinding wheel / Grinding on the coarse side of the sharpening stone / How to hone plane irons and chisels
• SHARPENING BITS AND DRILLS
  Sharpening the auger bit / How to sharpen the centre bit / How to sharpen the twist drill / How to sharpen awls
• SHAPING SCREWDRIVERS
  Shaping cold chisels / Shaping block scutches
• MAINTAINING WOODEN PLANES
  How to reface the sole / About the bedding of the cap iron / Fitting the wedge
• MAINTENANCE OF SAWS
  General maintenance / The action of the teeth
• ANGLE OF PITCH, SHAPE AND NUMBER OF SAW TEETH
  The ripsaw / The crosscut saw / The backsaw
• SETTING HANDSAWS
  How to set a saw / Setting the ripsaw / Setting crosscut and hacksaws
• FILING HANDSAWS
  Using the sawfile / How to file the crosscut saw / How to file the backsaw / How to file the ripsaw
• TOPPING A HANDSAW
  How to top a saw

The importance of good tool maintenance is something which is readily appreciated by everyone; the beginner will quickly realize that without maintenance, the finest tools are no more useful than the most Inferior ones.

Apart from their general maintenance in terms of cleanliness, rust prevention and avoidance of damage from rough handling, the most important aspect of maintaining tools is in the preparation and preservation of good "utting edges.

Until one has some experience in tool maintenance, one easily overlooks the fact that from the moment that a fine cutting edge is formed, it becomes the most delicate and easily damaged part of the tool. Even the lightest touch of another piece of metal can spoil the edge, wasting the work which has gone into malting it.

Such damage can be avoided in commonsense ways such as:

• By keeping the bench clear of tools which are not in use.
• By laying planes down on their sides or keeping the toe raised on a wood support so that the plane iron does not touch the bench top.
• By keeping chisels and saws in the box when they are not in use.
• By keeping the bench clear of ironmongery such as nails, screws, hinges, etc.
• And by putting tools down oii wooden surfaces only.

CUTTING ANGLES

Before you can proper'y maintain your tools, you need to know something about the shape of the cutting edges on tools like plane irons and chisels. A cutting edge is formed where the two faces of a wedge corae together at an angle, which is the cutting angle (Fig. 1).

Fig. 1

In general, the harder the material that you want to cut, the larger the cutting angle you need. For example, to cut steel or stone you need a tool with a cutting angle of about 70 degrees, like the cold chisel (Fig. £'. To cut a soft material like leather, a knife or a razor blade with a cutting angle of only a few degrees (Fig. 4) will work efficiently. Of course, you would not be able to cut steel with a razor blade.

In both these cases, it is important that the cutting edge of the tools is sharp, although they have different cutting angles.

For cutting woods we generally have one standard cutting angle for the tools like plane irons and chisels, although different kinds of wood can vary quite a bit in hardness. This standard angle of between 25 and 35 degrees is more or leas suitable for all types of wood (Fig. 3). The craftsman will find with experience the right cutting angle for his needs.

Note that the smaller the cutting angle, the more easily the tool will cut and also the sooner it will become dull.

SHARPENING PLANE IRONS AND CHISELS

Two different operations may be needed to produce a keen edge on these tools: grinding and honing.

Simply honing tools on a sharpening stone is all that is needed to sharpen them if they are dull but undamaged.

If the edges have been damaged , or worn down by many honings, they will need to be ground first and then honed. The grinding step is done on the rough side of the sharpening stone, or if the damage is very bad, on the grinding wheel.

ANGLE AND SHAPE OF THE CUTTING EDGE

For normal work, grind plane irons and chisels so that the length of the bevel is a little more than twice the thickness of the blade (Fig. 1). This gives an angle of 25 to 30 degrees.Fig. 1

The bevel should be ground straight or slightly concave, not rounded or convex (Fig. 2).

Fig. 2

For jack planes it is desirable to grind the corners of the blade slightly rounded as shown in Fig. 3. This lets ^he iron cut thicker shavings without causing deep grooves or plane marks in the wood surface.

Fig. 3

The cutting irons of smoothing planes, rebate planes and chisels should not be rounded,

When you sharpen the cutting iron of a plane, always remove the cap iron first. NOTES:

HOW TO GRIND PLANE IRONS AND CHISELS ON THE GRINDING WHEEL

When the cutting edge of a tool is badly damaged, it is ground on the grinding wheel. This is done by holding the tool at a constant angle to the rotating edge of the wheel (Figs. 1 & 2).

Each grinding makes the tool a bit shorter, and thus shortens its life. Use your tools carefully so that they don't need to be reground as often.

When you grind a piano iron or chisel on the grinding wheel, the following points are important to keep in mind:

Fig. 3

Before grinding, test the cutting edge for squareness. Put a try square on top of the chisel or plane iron, with the cutting edge projecting slightly past the try square blade (Fig. 3). Be careful not to touch the cutting edge with the square.

Hold the tool against the wheel in a manner that will produce a smooth, even bevel, with the desired angle,

If possible, adjust the work rest of the grinding wheel, so that when the tool is held firmly against the rest it will come into contact with the wheel at the correct angle (Fig. 2).

Fig. 2

Grasp the tool so that your first finger is against the work rest; this will enable you to replace the tool in the proper position after removing it for inspection or to dip it in water.

During grinding, a wire edge or burr is formed on the tool. You can feel this burr if you run your thumb across the edge at the back (below).

It is important that the grinding wheel always turns towards you (Fig. 1), so that the burr that is formed remains on the blade. If the wheel were rotating away from you the burr would tear off, leaving an uneven edge.

Turn at a moderately fast speed, not so fast that the gears whine or the grinder vibrates.

Always work with another person on the grinding wheel, so that he can turn the wheel while you do the grinding.

Hold the tool against the wheel with a medium firm pressure.

Move the tool from side to side across the face of the wheel.

Take care that the cutting edge does not become overheated and thus softened during grinding. Prevent overheating by frequently dipping the cutting edge into a tin of water.

Inspect the edge often, to see if the tool is being ground to the proper shape and angle.

With a bit of practice, you can check the cutting angle by eye, remembering that the lengt' of the bevel should be a little more than twice the thickness of the blade, Use a rule at first to check the length of the bevel and the thickness of the blade.

Continue grinding until the dull edge is removed, all the marks are removed, the edge is straight and square and the bavel lias the required angle. If the edge is not square, correct it during the grinding by pressing carefully more on one side than on the other.

Remove the burr or wire edge left by the grinding wheel by honing the tool on a sharpening stone.

GRINDING ON THE COARSE SIDE OF THE SHARPENING STONE

If the tool has a cutting edge with only a few marks in it and no serious damage, it can be ground on the coarse side of the sharpening stone, instead of using the grinding wheel.

Soak the stone in water and grind the bevel of the tool on the coarse side of the stone, until a slight burr or wire edge is formed.

When grinding, place the cutting iron on the stone so that the bevel lies flat (Fig. 1) and rub it with circular movements. Do not rub it just back and forth, as this makes the stone wear unevenly.

Be particularly careful to move your hands parallel to the surface of the stone and do not allow them to make a dipping movement, as this will round the cutting edge.

HOW TO HONE PLANE IRONS AND CHISELS

Honing is done on the fine side of the sharpening stone. Honing produces a keen edge.

After a slight wire edge has been produced on the coarse side of the sharpening stone, or on the grinding wheel, it is removed by honing on the fine side of the stone.

First, soak the stone in water. Place the tool perfectly flat on the stone with the bevel up and push it forward (Fig. 1). A few strokes will turn the burr from the flat side of the tool to the side with the bevel (Fig. 2).

When the wire edge turns, turn the tool over so the bevel is flat on the stone and hone lightly on the bevel (Fig. 3).

Then reverse the tool again and hone on the flat side.

If the honing is properly done, the wire edge will quickly become smaller and smaller (Fig. 4) and eventually disappear. The tool will then be sharp.

To check whether the tool is sharp, draw the nail of your thumb across the edge of the tool.

Marks, such as may have been caused by a nail, can be detected by holding the iron to the light. A sharp edge cannot be seen, while a dull one will show up in the light and appears as a narrow, shiny surface (Fig. 5).

If the tool is not held perfectly flat when the flat side is honed, a small bevel may be produced on the flat side and it will then be impossible to put the edge in good condition without regrinding it.

in alternately honing the flat :ind bevelled sides, make sure that the wire edge is actually turned from the flat to the bevelled side before you reverse the tool for honing on the bevelled side (Figs. 2 & 4).

To hone a slightly dull edge without grinding it, rub it on tb.3 sharpening stone in the same way, but only on the bevel side, not on the flat side.

Chisels are sharpened in the same way as cutting irons. Keep in mind that they are narrow and they should not be worked all the time in the centre of the stone, as this will quickly cause the centre of the stone to become hollow.

SHARPENING BITS AND DRILLS

Manual wood bits are usually sharpened with a small file. It is best to avoid too much sharpening. Your tools will last longer if you use tbem carefully and keep them in a good case, so they won't need sharpening so often.

SHARPENING THE AUGER BIT

Auger bits are sharpened as shown on the left (Figs. 1 & 2).

For the spurs, use a small file and sharpen from the inside face only (Fig, 1). The spurs are never sharpened on the outer faces, as this would change their diameter.

For the cutters, file from the top side (Fig. 2). Retain the original bevel and remove about the same amount of material from each side.

Hold the bit firmly to the edge of the bench during filing.

HOW TO SHARPEN THE CENTRE BIT

To sharpen the spur, file from the inside (Fig. 3). To sharpen the router, file the bevel from the top side (Fig. 4).

When sharpening the centre point, take care that the point remains exactly in the middle between the spur and the outside of the router.

HOW TO SHARPEN THE TWIST DRILL

Fig. 5

Grind the nose from the bottom (Fig. 5). Keep the original shape and angles and remove the same amount from each side.

Never file the flutes as this would change the diameter of the drill. If the drill is really out of shape, contact someone with metalworking experience.

HOW TO SHARPEN AWLS

To sharpen an awl you caa use the sharpening stone, or if it is damaged rub it down with a file. Pointed awls can be sharpened on a grinding wheel.

SHAPING SCREWDRIVERS

A screwdriver should be ground or filed to a very blunt end (Fig. 3). The two flat surfaces should be straight and parallel near the tip. The end should be square to the flat sides, and should be a little less thick than the width of a screw slot (Fig. 1).

If the end is rounded or sharpened to a knife edge, it will easily slip out of the screw slot and damage the slot. in Fig. 2 there are some exairples of badly shaped screwdriver tips.

SHAPING COLD CHISELS

Cold chisels should be ground or filed with the bevels on the cutting edge making an angle of about 70 degrees to each other (Figs. 4 & 5).

SHAPING BLOCK SCUTCHES

A block scutch should be shaped and filed to an angle of 70 degrees. Unlike the cold chisel, it is filed only from the inside (Fig. 6).

Maintaining Wooden Planes

HOW TO REFACE THE SOLE

Whatever the quality of the wood stock, the soles of all wooden planes eventually wear and require refacing.

Hefacing can be done on a large sheet of sandpaper, which is fastened to a true flat surface. The cutting iron of the worn plane is pulled Inside the mouth, not removed, for it is best to have the stock held in the usual pressure by the wedge.

- Sand the surface down, test it with a straight edge and winding strips and oil the wood lightly.

ABOUT THE BEDDING OF THE CAP IRON

It is essential that the edge of the cap iron should bed perfectly on the face of the cutting iron when they are screwed together (Fig. 1). Even the slightest gap between the two will allow a shaving to enter and block the mouth of the plane (Fig. 2).

Usually this problem is caused by a fault in the cap iron. The cap iron should be rubbed on a sharpening stone or filed to restore the true edge. Keep the cap iron clean and shiny.

FITTING THE WEDGE

After much use, the wedge may no longer fit well into the stock. Heavy use of the hammer when knocking it In may cause the wedge to become misshapen because of the pressure.

When it becomes difficult to remove the wedge in the usual way (by hitting sharply on the striking button), the wedge should be removed, cleaned and filed or sandpapered to the correct fit again.

The ends of the wedge can become worn and cause the plane to stuff because they are too far inside the plane. If this happens, recut the ends of the wedge (Fig. 3).

Maintenance Of Saws

GENERAL MAINTENANCE

Frequently give the saw a light coat of oil on the blade, to prevent rust. Keep the saw away from water.

Keep the saw in the toolbox and be careful not to damage the blade by putting other tools on top of It.

Keep the workbench uncluttered and be careful where you put the saw down.

If the blade gets bent or buckled, straighten it at once.

THE ACTION OF THE TEETH

In order to properly maintain saws, it is necessary to understand how the teeth should look and how they work.

The ripsaw tooth resembles the cutting edge of the chisel. Its cutting edge strikes at practically a right angle to the wood fibres and the effect is as if a series of small chisels were set one behind another. Each tooth cuts out the full width of its edge and carries away the shaving (Fig. 1).

The teeth of the crosscut saw and the backsaw have a different shape, size and action from those of the ripsaw.

The form of the teeth Is more like a series of knives that cut alternately on the two sides of the kerf (Fig. 2).

In sawing across the grain of the wood, the wood fibres must be cut on each side of the kerf so that a clean cut can be made. The teeth are therefore formed Into sharp points on the outer side, so that they cut the fibres accurately.

A cut is started as the teeth make fine cuts, similar to the cuts of a knife, across the wood surface. Then as pressure is applied, the teeth go deeper and deeper, gradually bringing into action the full cutting edge of the teeth.

ANGLE OF PITCH. SHAPE AND NUMBER OF SAW TEETH

The angle of pitch of the saw teeth is important in the maintenance of the saw. This angle is the measure of how far the face of the tooth is leaning from the vertical. The angle of pitch for the different saws is shown on the left page.

The smaller the angle of pitch, the faster the saw will cut and the more often it will need resharpening. A large angle of pitch means a longer life for the blade, while a small angle means more frequent resharpening and thus a shorter life.

THE RIPSAW

The blade of the ripsaw has 4 points (teeth) per 25 mm. The teeth of the ripsaw are rather big (Fig. 1).

The angle of pitch of these teeth is very small, from 0 to 3 degrees. This small angle means that the ripsaw will not cut properly across the grain, because the teeth will tend to tear the fibres. This saw is used only for cutting with the grain, where there is not any danger of tearing the fibres.

THE CROSSCUT SAW

The blade of this saw has 6 to 8 points per 25 mm, so its teeth are smaller than those of the ripsaw. The angle of pitch of the teeth is greater in order to get cleaner cuts; this also makes the work slower. The angle is between 12 and 15 degrees for this kind of saw (Fig. 2).

Do not use this saw for cutting along the grain; it is not designed for that and it will not guide as well as the ripsaw.

THE BACKSAW

The blade of the backsaw has 10 to 15 points per 25 mm, so the teeth are still smaller than those of the crosscut saw. The angle of pitch Is between 15 and 20 degrees (Fig. 3).

SETTING HANDSAWS

There are two main operations involved in sharpening a handsaw:

• a. Setting
• b. Filing

In order to make sure that the saw blade moves freely in the saw cut without any side friction, the saw teeth must be set. This is done by slightly bending the teeth at their tips (Fig. 3) to give more clearance in the kerf (saw cut). A saw should never be given more set than is necessary for the blade to move easily in its kerf. Too much set will cause the blade to wander out of line, too little set can cause the saw blade to buckle.

Only the tips of the teeth are set, never more than about 1/3 rd of the length of the tooth (Fig. 4). If you set the saw deeper than that you will buckle or crack the blade.

A saw need not be set every time it is filed, particularly if only a light filing is required. A saw can sometimes be filed two or three times before it needs to be reset and filed again.

SAW VICE:

During the maintenance of a saw, it must be securely fixed in position. A saw vice is used to hold it; either the wooden type (Fig. 2) called a horse, or the metal type (Fig. 1) which grips the blade more strongly but does not grip the whole length of the blade.

Another type of wooden saw vice can be made by fixing the two wooden jaws to the handle of your toolbox.

HOW TO SET A SAW

To do the setting, we use a setting tool. This can be a strip of metal with some cuts in it, the cuts being the thickness of the different saw blades (Fig. 1). Setting has to be done by eye, and practice is needed to get the right bend. The top of the saw vice can be bevelled to act as a guide for the setting tool (Fig. 2).

Hoxd the saw firmly in a good position. When setting the first tooth, take care that you bend it to the same side that it was bent before.

Start at the heel of the blade and bend every second tooth. When you finish one side, turn the blade around and do the other teeth (Fig. 3).

It is important that the set is exactly the same on each side, otherwise the saw will run (saw out of line).

Instead of the setting tool mentioned above, pincer type sawsets (Figs. 4 & 5) are often used.

You simply place the set over the tooth and squeeze the handles. These sawsets are adjustable, so when you use an unfamiliar one, it is best to set a few teeth and examine them before you set the whole saw. If the teeth are set too much or not enough, you can then adjust the sawset accordingly.

SETTING THE RIPSAW

When the saw cuts with the grain, like the ripsaw, the fibres of the wood don't tend to move back into the cut, so the ripsaw doesn't need a big set to ha'e enough clearance between the blade and the kerf.

SETTING CROSSCUT AND HACKSAWS

Crosscut fibres tend to move back into the kerf, so these saws need a bigger set to get enough clearance.

It is important to note that the wider setting of these saws makes them unsuitable for cutting with the grain, because the kerf will be too wide to guide the saw.

FILING HANDSAWS

After the saw has been set it can be filed.

Secure the saw in a saw vice, with the teeth sticking out just a little way from the vice jaws. If the teeth stick out too far, the filing will cause a screeching sound.

The top of the saw vice should be at about the level of your armpits, or slightly below (Fig. 1). While filing, you must be able to constantly check the shape of the teeth and this rather high position enables you to see them properly.

In order to avoid eyestrain and ensure a good job of filing, it is essential to have good light. Work in front of an open window if possible, so that the light shines on the saw teeth.

USING THE SAWFILE

Small metaiworking files with a triangular cross section are used for filing saws. The following points are important to remember in using the saw file:

Hold the file handle in your right hand (Fig. 2).

Hold the tip of the file gently between your thumb and forefinger of the left hand (Fig. 2).

Exert pressure on the forward stroke only.

Make long slow cutting strokes, not short fast ones.

Keep the file level (Fig. 3).

Use enough pressure to make the file cut, but no more.

During filing, a small burr is formed at the tip of the teeth. This burr can improve the cutting action of the saw when it is filed in the right direction. Therefore the saw must always be filed from toe to heel (Fig. 4).

HOW TO FILE THE CROSSCUT SAW

Study Fig. 1 very carefully to understand the proper starting position for filing this saw. Work according to the following sequence:

1. Place the toe of the saw in the saw vice with the handle to your right.

2. Find the first tooth in the toe that is bent towards you. Place the file in the first gullet (V-notch between the teeth) to the left of that tooth (Fig. 2, arrow).

3. Hold the file across the saw blade at an angle of about 70 degrees, with the point towards the saw handle.

4.If the teeth are of the proper shape (see section on Angles of Pitch) press the file gently into the gullet and let it find its own placement against the two teeth (Fig. 2). Remember to keep the file level.

5.Push the file forward, cutting the front surface of one tooth and the back surface of another.

6.Release the pressure on the file during the backstroke.

7. File every other gullet until you are about halfway through the saw, then make a pencil mark at this point.

8.Shift the blade in the vice until the head end is held more securely and continue filing every other gullet until you reach the handle.

9. When every other gullet has been filed from one side, turn the saw around in the saw vice so the handle is to the left (Fig. 3).

10.Find the first tooth In the toe of the saw that is bent towards you and put your file Into the gullet to the right of that tooth.

11.Hold the file at an angle of about 70 degrees across the blade, with the point towards the saw handle.

12.File every other gullet as before, until you reach the saw handle.

-REMEMBER: - Inspect your work frequently to make sure that you are getting the teeth properly shaped. Remember that the angle of pitch must be correct.

-Throughout the filing, give each tooth the same number of strokes with the file. This helps keep the teeth all the same size and shape.

• If you get one tooth out of shape, don't be too concerned; it can be left as it is.
• Turn the file occasionally, so that it is used evenly.

If you think you have lost your place or skipped a gullet, look for the last shiny tooth in the light.

HOW TO FILE THE BACKSAW

This saw is filed in the same way as the crosscut saw, except that the angle of pitch is different.

Be careful with the pressure you apply with the file, because the teeth are yery small and are easily filed out of shape.

HOW TO FILE THE RIPSAW

The same general procedure is used for filing ripsaws as for crosscut saws. There are two important differences:

1.The angle of pitch is different.

2.The file is held at 90 degrees, not 70 degrees, to the blade (Fig. 4).

(Some people file the ripsaw from one direction only, filing all the teeth at once instead of filing every other tooth and reversing the saw).

TOPPING A HANDSAW

If you always file the saw correctly, without twisting the file or filing some teeth more than others, the teeth will always have the correct form and equal height.

When you make small mistakes in filing, or use the saw carelessly, the teeth will become out of line, different in height and irregular in shape. The result is that only some of the saw teeth can cut; the others don't touch the wood (Fig. 1). Topping is done to correct this problem.

WELL KEPT AND MAINTAINED SAWS NEVER NEED TOPPING!

HOW TO TOP A SAW

Topping must always be done before you set or file the saw.

-To top a saw, you run a flat metalworking file over the ends of the teeth, moving along the length of the saw. Be very careful to keep the file square to the saw blade and flat.

- One way to do this is to grasp the file in both hands by the edges, thumbs on top and the fingers under, touching the saw blade and guiding the file (Fig. 2).

-A wooden block may also be used to hold the file in the proper position (Fig. 4).

- File until there is a small shiny point on each tooth. When you have made two or three light strokes and there are still some teeth that have not been touched (Fig. 3, previous page), don't keep on filing. Too much topping will make it difficult to reshape the teeth.

- Next, file the teeth to the correct form again. This is called reshaping the teeth. When all the teeth have tho same height and shape they are ready to be set and filed again after setting, to sharpen them.