Topic 2:

How to measure and mark out

When working with wood, accuracy is very important. As a result, woodworkers always use the millimetre as the standard unit of measurement. Centimetres are commonly used elsewhere but they are simply not accurate enough to be used in woodworking. Therefore, it is important to understand what a millimetre is and to use it consistently.

There are 10 millimetres in 1 centimetre

There are 1000 millimetres in 1 metre

Woodworkers will use a variety of measuring devices, the most commonly used measuring device is the steel rule and they are available in 3 lengths, 300mm, 600mm and 1000mm. If you look carefully at the image below you will see along the upper edge, marks every 1mm, on the bottom edge, you will see marks every ½ mm

What is the difference between a ruler and a rule?

A rule may sometimes be called a ruler, and the terms rule and ruler are often used interchangeably. Generally a rule and a ruler are distinguished as: a rule, usually, measures straight from its edge; a ruler starts its measurement a little way in from the edge.

But why?

Often woodworkers might need to measure how deep a slot or housing is, this can be done with a rule, by dropping it into the slot and then reading the measurement where it aligns with the surface.

Let's practice measuring

The following tools are commonly used for measuring and marking-out when using wood:

A sharp pencil – Used to mark lines and centres for cutting or joining. Pencil marks are easy to remove afterwards. It is best to use a sharp pencil very lightly. This gives thin, light lines that don't engrave the workpiece.

Steel rule – Used to measure materials for cutting or joining. Best used flat against the face side and face edge. This ensures that measurements are marked from one consistent spot. Measuring with a steel rule and a sharp pencil can give accurate, removable marks.

Try square – Used to mark lines perpendicular to an edge. The woodworkers try-square is composed of two main parts - the stock and the blade. The blade is made from hardened and tempered steel which makes it resistant to damage. The stock is usually made from rosewood although cheaper versions can be made from plastic or cheap woods.

A brass face is added to the stock to ensure a straight edge. A typical use of a woodworkers try-square can be seen opposite. The try-square is pushed against the straight edge of a piece of wood and a sharp pencil or a marking knife is then used to mark a straight line across the material, at exactly 90 degrees to the edge. This type of marking is used if a joint is to be cut or the end of the material is simply to be sawn away.

An alternative use of a try-square is to test the edge of a piece of wood to check how square it is (has it got a 90 degree angle along its length?). The try-square and material are held up to the light and the try-square is moved along the length of the wood. If light shines through any gaps between the blade and the wood, then the edge is not square.

Marking on a side

Marking on an edge

Checking outside corner

Checking inside corner

When making the phone safe project, it is important to remember that we measure using a rule and we mark out using a try square - we NEVER mark out using a rule. Why do you think this is the case?

Measuring timber

When measuring a piece of timber, the first thing to do is measure across the end grain along the widest part, this will give you the Width of the timber. Then measure across the end grain in the other direction to find the Thickness of the timber. Once you have figured this out, you can then measure away from the end grain to get the Length of the timber.

When you look at the end of a piece of timber, the widest part is the Width, the other direction is the Thickness. The biggest measurement that you will get is the Length of the timber, so another way of working out the difference between them all is this: The biggest measurement is the Length, the next biggest is the Width and the smallest measurement is the Thickness.

Report abuse