These are used for making joints, paring wood and cutting recesses to take fittings such as hinges. They are also useful for cutting away areas of rotting woodwork. Chisels have a flat steel blade with a cutting edge on the end. The handles can be of wood, in which case it is important when necessary to tap the handle to use a wood mallet, or they can be of tough plastic, when an ordinary hammer will suffice. New chisels are not sharpened and need honing on an oilstone before they can be used.
Types of chisel
1, 2 and 3. Paring chisels in three different widths, 4. Bevel-edge chisel, 5. Firmer chisel, 6. Bolster chisel for heavier work.
When buying a chisel avoid any that are thin at the blade shoulder (a chisel's weakest point). Look for those with a slight taper from shoulder to blade end.
Bevel-edge chisel, This is the most common type of chisel. It has sloping sides which mean that it can be used in confined spaces to undercut or cut sideways into the corner of an acute angle. Sizes from 6mm (3/8in) to 38mm (1½in).
Firmer chisel, The sides of this chisel are straight rather than bevel-edged and it is therefore considered a stronger tool. However, strength also comes from the steel used and the design of the blade. This chisel is good for making partition frames or fencing or for cutting out notches for pipes running over joists.
Mortise chisel, This is the strongest chisel of all. It has a thicker blade and is used for cutting the mortise of a mortise and tenon joint. It is designed for striking with a malet and for levering.
Paring chisel, This can be bevel-edged or straight-sided but the blade is long and thin. It is useful for cutting out deep holes or paring long slots in wood such as those needed for bookcase housings.
Bolster cisel, Apart from cutting masonry, this chisel can be used for a number of levering jobs such as taking up floorboards. Lengths range from 175mm to 190mm (7 to 7½in).
Bevel-edge chisel, This is the most common type of chisel. It has sloping sides which mean that it can be used in confined spaces to undercut or cut sideways into the corner of an acute angle. Sizes from 6mm (3/8in) to 38mm (1½in).
Firmer chisel, The sides of this chisel are straight rather than bevel-edged and it is therefore considered a stronger tool. However, strength also comes from the steel used and the design of the blade. This chisel is good for making partition frames or fencing or for cutting out notches for pipes running over joists.
Mortise chisel, This is the strongest chisel of all. It has a thicker blade and is used for cutting the mortise of a mortise and tenon joint. It is designed for striking with a malet and for levering.
Paring chisel, This can be bevel-edged or straight-sided but the blade is long and thin. It is useful for cutting out deep holes or paring long slots in wood such as those needed for bookcase housings.
Bolster cisel, Apart from cutting masonry, this chisel can be used for a number of levering jobs such as taking up floorboards. Lengths range from 175mm to 190mm (7 to 7½in).
Sharpening a chisel
Apart from sharpening when new, chisels need checking regularly before use. A blunt chisel is difficult to use and produce poor results.
Use a medium or fine oilstone to sharpen and apply light oil or paraffin, which is cleaner, to the surface. Remove the surplus with a rag. Hold the handle of the chisel in one hand and steady the blade with the other, keeping the chisel, bevel side down, at anangle of 25° for the bevel, then at 30° for honing. If the angle is increased the chisel becomes harder to use, if it is decreased it will bluct rapidly. Use a honing guide to ensure the correct angle (1).
When a wire edge starts to form turn the blade flat on the surface, rub it over the stone. Rub the back of the blade over the stone in a side-to-side movement (2). Repeat this action untill the sliver of steel on the tip of the chisel has disappeared.
If a blade is damaged, with nicks in it, or has rounded corners it will need regrinding. This is hard work and it is best to take it to a local DIY shop, which can probably arrange for this to be done.
For safety and to protect blades, use a well-fitting blade guard on chisels when not in use.
1 Used a honing guide to hold the bevelled side of the chisel at the correct angle - in this case, 30°.
2 Rub the back of the shisel from side to side to remove the wire edge created by honing.
Using chisels
Cuting a halving joint, Mark out the width lines across the top of the timber, and width and depth lines down the sides. Make a saw cut to the waste side of each width line and down to the depth line (1).
Place securely in a vice, making sure the timber is horizontal. Use the chisel pointing slightly upwards and chisel out from one side to the centre, then the other (2). Finally, use the chisel horizontally to shave off the remaining fibres. Clean out corners.
Cutting a mortise, Mark out the area of the mortise. Use the correct width chisel and drive it into the centre of the waste area, using a mallet or hammer for a wood or plastic handle respectively, to a depth of about 5mm (¼in) (3). Make successive cuts either side of this to within 3mm (1/8in) of each end and remove waste.
Mark the final depth on the chisel with tape and gradually work down through the wood to this depth (4). Clean up the edges with a vertically held chisel. Continually check fit with the other half of the joint.
Paring wood vertically Mark the curve required on your wood and cut off the corners with a tenon saw (5)
Pressing down with the thumb, cut towards the marked line, taking off finer and finer shavings (6).
1 Use a tenon saw to make clean cuts on each side of halving joint.
2 Chisel away the waste, working in from each side of the timber.
3 Make a series of vertical cuts into a mortise, with the chisel vertical.
4 Remove the waste, using tape as a depth guide on the chisel.
5 Trim the end of a piece of timber with a tenon saw.
6 Use a paring chisel, held vertically, to pare away the waste.
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