Cutting edges don't stay sharp forever.

In fact, tools that are designed to be razor sharp - such as knives and chisels - tend to go blunt very quickly while you're using them, especially if you're cutting hard materials.

In the case of utility knives, you can simply replace the blade once the edge goes dull.

But chisels need to be rubbed up on an oilstone - or 'honed' - regularly.

In some cases you may need to do this several times in a single work session.

The same applies to the blade (called the 'iron') in a hand plane.

Some tradespeople also like to sharpen their own electric planer cutters.

But many people find it easier to send them to a professional sharpening service, or simply replace them with a new set.

Note that plywood and particleboard will dull sharp blades more quickly than solid timber, because the glue in these manufactured boards is harder than the wood fibres.

Below is the general procedure for sharpening chisels.

The same process applies to hand plane irons.

Also below are some hints on how to sharpen drill bits, since they too will need touching up from time to time.

Chisels

There are two important angles at the sharp end of a chisel - the grinding angle and the sharpening angle.

The grinding angle is formed on a grinding wheel. It should be between 25° to 30° from the face of the chisel blade.

The sharpening angle is between 30° to 35°. This is the angle that gives you a sharp cutting edge, so it's the one you must maintain by 'honing' the chisel regularly on an oilstone.

If you're cutting softwood or doing very delicate work, keep the angle closer to 30°, because that will give you a sharper blade. But for harder materials, an angle closer to 35° is better, because the edge is less brittle, so it's less likely to break away while you're cutting.

Honing

Here's how to hone a chisel:

1. Spread a small amount of oil on an oilstone.
   
   
2. Put the back of the chisel blade flat on the stone and rub it back and forth to clean it and take out any burrs.

3. Turn the chisel over and raise it to the point where the grinding surface is flat against the surface of the stone.
   
   Then lift the chisel up slightly further to find the sharpening angle.
   
   
4. Rub the chisel in a figure-eight pattern on the stone to hone it.
   
   A tiny burr will form on the back of the blade at the edge, called a 'wire edge'.

5. Turn the blade over and hold the back flat against the stone.
   
   Rub the blade back and forth to remove the wire edge.
   
   
6. If the blade is not sharp or the wire edge has not fully come away, repeat steps 3 and 4, using a few strokes only, until you achieve a sharp edge.

Grinding

After repeated sharpenings, the angle of the sharpening bevel will start to increase as the end gets progressively shorter.

Eventually, you'll need to regrind the chisel to get back to a full-length 25° flat surface.

When you're grinding the chisel, be very careful to avoid overheating the edge, because this will cause the steel to lose its strength or 'temper'.

Cool the edge frequently by dipping it in water.

The video clips referenced in the learning activity below shows the procedures used to grind and hone a chisel.

Drill bits

Like chisels, drill bits will lose their edge at different rates, depending on what materials you're working with.

Metals, manufactured boards and surface laminates will all take their toll on the cutting edges of a drill bit.

There are various machines and jigs designed for sharpening drill bits. Some of these are quite cheap and available in any hardware store. But many tradespeople like to sharpen their own drill bits by hand, using either a grinding wheel or hand file.

The equipment and technique you use will depend on the type of drill bit you're sharpening.

For kitchen and bathroom cabinetmaking, you'll probably use a twist drill most of the time for small holes and a spade bit for larger ones.

There may also be times when you use an auger or brad point.

Follow the links in the learning activity below for more information on how to sharpen each of these types of drill bits.