Screws can provide a strong, neat fixing to walls, man-made board, timber and even concrete, provided you choose the right fixing for the job.
Screws pull together the surfaces to be joined as the thread on the shank is rotated. The fixing is very strong and can be taken apart easily. Choose brass or plated (stainless-steel) for outdoor work. Black lacquered versions are also sold, to match black hinges and latches.
The screw length should be about three times the thickness of the timber it is fixing in place. The thicker the screw, the greater the grip.
Screws are sold according to length and gauge (shank diameter). The length is defined as the distance between the tip of the screw and the surface of the wood. The greater gauge number, the thicker the screw, with 20 being the highest.
Types of screw
Traditional screw with a long shank. Still widely used and most suitable for traditional pieces of furniture and restoration work.
Probably the most popular type of screw because the cross-shaped slot tends to prevent the screwdriver slipping.
Used mostly for fixing items without countersink holes. The top is rounded and sits out from the surface.
This is a sort of hybrid from the last two. The top is slightly rounded and the base countersunk. It is most commonly used for fitting ironmongery, such as door handles.
As the name implies, this is most commonly used for fixing mirrors. It has a countersunk slotted screw, which is fixed first. A dome shaped chrome cover is then fastened into the top of the screw. When used for fixing mirrors or other fragile objects, a small rubber insert is set in the screw hole of the item to prevent the metal of the screw damaging it.
This is similar to the traditional countersunk type, but has a deeper thread which allows it to grip better in chipboard and the like.
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.
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 screw
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.
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.
Pilot holes are clearance holes drilled in the surface. They are narrower in gauge than the shank of the screw. They have two important benefits. Firstly, they make the process of doing up the screw easier as there is less wood to be cut into by the screw. Secondly, they help prevent the wood splitting when the screw penetrates the surface.
File or grind distorted or blunt slot head screwdrivers to make the tip flat and square. The blade tip should fit across the full length of the screw slot.
When filing or grinding, wear safety goggles to protect your eyes.
Don’t use screwdrivers for anything but driving screws as the hardened steel of the shaft may snap.
Using brass screws
As brass is a soft metal, it’s important to make a pilot hole in any material before a brass screw is driven in.
Take a steel screw of the same gauge and size and screw this in to form the threads.
Rub the brass screw along a candle to lubricate it, making turning easier.
Do not use too much force or the head will shear off.
For awkward tasks, such as fixing a screw at the bottom of a counter bored recess or in an awkward corner, it’s worth buying a screwdriver magnetiser.
Rub the screwdriver up and down the tool to magnetise it and allow small fixings to be held while you position them.
You can also buy clips to fit on screwdrivers, holding the screw on the tip.