Fig. 27 shows a try square being used to mark a line on a piece of wood. The timber has been selected for its working properties and appearance. Different t...
Question 1 Report
Fig. 27 shows a try square being used to mark a line on a piece of wood. The timber has been selected for its working properties and appearance. Different types of timber have different characteristics that affect their suitability. The grain direction and moisture content affect how the timber can be worked.
It is safe to use. The base is wide.
The parts are held in place with screws. It comes in many sizes and shapes.
(a) Name the parts of the try square labelled A and B. [2]
(b) Explain why the stock must be pressed firmly against the datum edge of the wood. [1]
[Total: 3 marks]
Answer Details
(a) The parts of the try square:
- A is the blade. [1] The blade is the thin, flat metal strip that extends perpendicular to the stock. It is made from hardened steel to keep it straight and true, and it provides the reference edge against which a pencil line is drawn on the workpiece.
- B is the stock (handle). [1] The stock is the thicker, shorter section that sits against the edge of the workpiece. It is usually made from hardwood or metal and provides a firm, flat reference surface to press against the datum edge (the straight, prepared edge of the timber).
(b) The stock must be pressed firmly against the datum edge of the wood to ensure that the marked line is at exactly 90 degrees (a right angle) to the edge. [1] If the stock is not held firmly against the datum edge, it can shift or tilt, and the line drawn along the blade will not be perfectly square to the edge. This would result in inaccurate cuts, joints that do not fit properly, and components that are not the correct size or shape. The datum edge itself must be straight and true for this to work, which is why it is typically prepared first with a plane.
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