Types of Nails and screws
In indoor work small nails are used mainly to attach sheet materials to frames. They can also be used though, in ‘dovetail-nailing’ to strengthen plain butt joints.
Nails may be round, with round, flat heads, or oval, with oval heads.
Round nails split wood more easily but they do grip sheets well. Ovals should be used in jointing to reduce the risk of splitting. Blunt the tip with a sharp blow of the hammer before driving a nail into thin wood. This makes it cut through the wood fibres rather than force them apart in splits.
Where fastenings are made into the end grain of wood, that is, into the sawn-off ends of timber, nails often hold better than screws, which tend to chew out the wood rather than grip it.
- Nails have a number of advantages, though highly skilled wood-workers tend to look down on nailing as rather primitive. In fact, for fastenings that are not under great stress and in certain types of joints, nails are better than screws. But it is true that over a number of years, nails may not have the holding power that screws retain.
- Nails are bought by weight, the number in a pound obviously depending on the size. There are two main sorts, the round and the oval. Round nails have largish, round heads and are themselves round in the shaft.
- Oval nails have an oval shaft and head that can be driven into plain wood with less risk of splitting it. In general, one would use oval nails in all possible cases. The heads may be driven right into the wood, and then covered with a plastic putty, so as to be completely invisible. Round heads are much more difficult to conceal successfully.
- Masonry Pins are a special kind of extremely hard and tough nail, supposed to be driyen directly into brick or concrete.
- In practice they are far from effective and many makes will bend and snap dangerously on being driven. We do not recommend them, , unless you can find the most expensive kinds with some guarantee against snapping.
- For fastening thin sheets of plywood etc. to framing, one may use either small, round headed nails, in steel or better, in brass, or one may obtain the special kind of thin nails known as panel pins. Where hardboard is being applied, get the special hardboard fixing pins which have a pyramid topped head. These can be driven right under the surface of the board and almost disappear.
- Glue of various kinds is used mainly in applying sheets, especially of plastic laminates, and for reinforcing joints. Since it is rather harder to get perfect joints using glue alone, we have shown as a rule structures using screws or nails. But in nearly every case you can improve the joint’s strength by applying glue to the parts before screwing them together.
Screws are made of steel or brass. The heads may differ in shape, the main sorts being round head, which is a dome shape; countersunk head, which is designed to fit into a hollow cut in the wood surface; and raised head, which combines the two, being partly countersunk but with a raised, slightly domed head. These look less clumsy than the full round head type.
- Steel is by far the stronger material, but rusts in damp conditions and may stain some hardwoods. Brass is rustproof, more expensive and weaker, and so it pays to drive in a steel screw first, to make a thread, before finally using a brass one.
- The commonest error when joining two pieces of wood with a screw is to get the screw tightly jammed in the upper piece. The correct procedure is to make a hole in the upper piece large enough to accept the shank (unthreaded part) of the screw freely. Then bore a thinner hole in the lower piece to accept the centre core of the threaded part. Thus the thread itself bites only into the wood of the lower piece.
- Tightness around the screw shank will put great strain on the lower part of the wood where the thread penetrates and may rip it clean out.
- Ordinary, steel woodscrews are the most common type used in fitted furniture. Those known as Countersunk and having flat-topped, tapered heads are most useful. Since they may be of different thicknesses, a system of numbering is used, thin screws having low numbers, fatter screws higher numbers. For example, a number 6 screw would be much thinner than a number 10. The most generally useful thicknesses are 6, 8 and 10, and in lengths of 1 in., 11 ins. And 2 ins. One can also buy screws made of brass, but these are much more expensive. They are normally only used for fitting hinges and similar jobs where their heads remain visible and are not easily painted. (Brass does not rust.)
- Socket-head screws have a shaped hole instead of a slot. This makes slipping of the screwdriver less likely. Some workers favour this type, but we ourselves find little real advantage over the almost universal slotted head with its simple screwdriver. For use with Rawlplugs, there are special sizes that are best bought with the plugs, although a number 8 plug, for example, will accept a number 8 screw.