Screw types and their uses (page 2)

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Chipboard screw

This is similar to the traditional countersunk type, but has a deeper thread which allows it to grip better in chipboard and the like.

Twin thread

As the name implies, this has two deep threads interwoven with each other. The shank of the screw is narrower, which gives the screw greater grip.

Self tapping

This is used in harder materials such as metal and fibreglass. A hole, the gauge of the shank, is drilled first. The screw then cuts a thread into the material as it is tightened.

Clutch head

This has a unique crosshead pattern which enables the screw to be done up , but not undone. It is used for fitting locks and other security devices.
Before fitting, use an ordinary screw of the same size. This way you'll have a chance to make minor adjustments to your work before finally fitting the clutch head screw which cannot easily be undone.

Dry wall screw

This is thinner than a normal screw, with a sharper point. The thin head enables it to be driven into the surface of board or studwork easily. It is commonly used on stud walls for fixing the plasterboard, and sometimes the timberwork itself.

Coach screw

This has a large hexagonal or square head and is used for decking and garden joinery. A pilot hole should be drilled, and the screw fastened with an appropriate sized spanner or socket.

Continued...

• Screwing wood
• Nails
• Wall fixings