The purpose of the screw is to provide a strong attachment to walls, concrete, manmade board and timber. Screws should provide resistance to corrosion and be easy to use, although often how easy the screw is to use depends on you using the right screw style and length for the job. Screws work by pulling taught together the surfaces as the thread on the shank (the length of the nail) is rotated.
The screw's strength lies in its ability to affix itself to the surrounding material and hold itself there securely, whilst also being easy to remove. A long screw will therefore have more staying power than a short screw of the same gauge (shank thickness). Screws are sold by length and gauge, with 20 being the highest gauge number. Ideally, the screw length should be around 3 times bigger than the thickness of the wood it is holding in place.
As well as finding the right length and gauge, wood screws are also categorised by their drive and the shape of the head.
Slotted head - single slot in the screw head that can be turned by a basic screwdriver.
Crosshead Philips - requires the correct screwdriver to prevent slipping and damage to the screw.
Crosshead Pozidrive - these can also be screwed with a Philips screwdriver.
Countersunk - these are flat or slightly scoop-headed so that the head is flush with the surface. It is necessary to use a special drill bit to make a countersunk hole.
Round head - the screw heads rest on the surface with a round protrusion. They are usually used where it is not possible to countersink. Some round heads are made in conjunction with cover heads for decorative features.
Raised head - Combining properties of both of the above, these are countersunk with a slightly domed head. They are used where a neat finish is required, as with door handles.
To screw two pieces of wood together, you will first have to secure them into place so that they cannot slide. Smaller pieces can be held still, or it may be necessary to use a clamp. Mark the screw's designated position with a pencil, and drill your initial hole, which is a little narrower than the screw, into both pieces of wood.
Now make the hole in the upper piece to match the gauge of the shank. If the hole is for a countersunk screw, also use a countersink borer to create the correct hole. Put the screw in position and tighten with the correct screwdriver.
Nails are made for purposes of fast attachment for pieces of wood that do not need to be separated. Nails are often used in unseen areas like floorboards. It is easier to hammer together softwood than it is hardwood, as nails in hardwood tend to bend rather than penetrate the wood. Avoid bright coloured steel nails in areas that are prone to moisture or humidity change. Bright nails have no protective coating and so are more likely to corrode.
To make a really strong nailed joint, use a nail which is 3 times the thickness of the thinnest piece of wood. Hammer in a nail in the usual manner, and then angle the following nails at around 25 degrees, facing each other in pairs. This prevents them from easily pulling out.
Round wire nail - used for general applications and rough carpentry where the appearance is not an issue but strength is important. It can cause wood to split.
Oval wire nail - a long nail that requires a sturdy hand to hammer it in.
Masonry nail - made from hardened steel or zinc, masonry nails affix wood to masonry like bricks and breeze blocks.
Lost head nail - suitable for visible areas, the head of the nail can be hammered beneath the wood surface.
Panel pin - popular way for attaching small mouldings and cabinets, the panel pin is round and light.
Annular nail - has teeth-like ridges on the shank to hold strong joints. Ideally used in securing joists or fixing plywood to prevent movement.
Square twisted nail - an expensive nail, it twists into the wood quite like a screw, and thus offers comparative security in its grip.