Which nail, screw, bolt or anchor?
- Nails are steel pins that are driven into timber with a hammer or nailer. The most common are bullet head (for hardwood and finishing) and flat head (for softwood), but nails with twisted or otherwise deformed shafts give extra holding power where needed, such as in decks.
- Screws come in a wider range of materials than nails and may also be plated with chrome, brass, and so on. Always use the correct driver for the screw head, otherwise it will be damaged. Items that are screwed together can be taken apart.
- Bolts are used where two materials do not allow nail or screw fixings, where ease of disassembly is needed, or where screw or nail fixing would not be secure enough. Washers broaden the bearing area and protect the surfaces from the head and nut.
- Anchors are used for surfaces that you can't successfully screw or nail into, or where you do not have access to the rear for bolting. Use hollow wall anchors for sheet materials and expanding or chemical anchors for masonry.

Nailing basics
Past experience may tell you that for every nail you get in, you'll bend another or split the wood. How do you nail with 100 per cent success? Here's a little secret: nobody nails with 100 per cent success. Following are a few helpful tips. Wherever possible, nail from the thin piece into the thick piece. Nails hold by friction, so the more friction in the bottom piece the better. When nailing, aim to penetrate 10 times the nail diameter into side grain, and 15 times nail diameter into end grain. Nails that are twisted or have been hot-dip galvanised will hold even better. In most cases you only need two nails per framing joint. If using more because you are nailing along a board, stagger the nails to avoid splitting along the timber. Choose the thinnest nail that will do the job. It is less likely to split the timber, and they are easily punched below the surface and then filled over.


Case for predrilling
Where timber is prone to splitting or you are nailing near the ends of boards, predrill to about 70-80 per cent of the nail diameter. This also helps when the nail, of its own accord, decides to follow the soft layers in timber, such as Oregon, and go in at an angle. Always predrill the edges of boards, such as MDF and thin particle boards and plywoods, before nailing, to avoid splitting and bulging.

Snipping the points off nails
When nailing small items such as mouldings, snip off the point of the nail with pliers or side cutters. This allows the nail to punch through the timber fibres rather than wedging them apart, which leads to splitting. Blunting the point by tapping it with the hammer will have a similar effect.

Holding the hammer and safety
A claw hammer is designed to drive nails and pull them out. Hold the hammer by its handle and swing it freely in the same plane as the nail to hit the nail squarely on the head. Use sufficient force to drive the nail. Just tapping a nail is not enough to drive it in, but is sufficient to bend it. With time, a hammerhead becomes smooth. Rub the striking surface with sandpaper or on concrete to roughen it so it won't skid off and bend the nail.

Starting a nail
To start a nail, hold the point in contact with the timber just where you want the nail to be driven. Tap the head sufficiently so the nail supports itself. Remove your fingers and swing freely to drive in the nail. The first strike is the time when the nail may go flying so don't forget your safety goggles. To get in a bit of nailing experience, grab a plank of scrap timber and practise with soft and hardwood.

Punching nails
Nail punches let you drive nails below the surface ready for filling, such as when making furniture. Also use them when face-nailing timber, because a slip with your hammer will leave an ugly mark otherwise. Hammer the nail to within 1mm or so of the surface, then finish with a nail punch. Punching also ensures the head has actually pulled the pieces of wood together.

Extracting nails
To pull out bent nails, use the claw of the hammer and place a timber offcut under the fulcrum of the hammer, to avoid marking the timber and to give better leverage. Sometimes it's a better idea to punch the nail right through the timber and draw it out the other side.


Screw basics
Screwing is a little more involved than nailing, but it has the potential to form very strong joints, with the added advantage that they can be taken apart (as long they haven't been glued as well).
- A screw should be long enough to penetrate into the frame or base you are screwing into, without poking through the back. Screw from the thinner piece of material into the thicker piece. Ideally, two-thirds of the screw should be in the bottom piece, or three-quarters when screwing into end grain, as the screw thread tends to cut the wood fibres.
- Choose countersunk heads when you need a flush finish. Round or pan heads are used when the head can remain proud or when screwing sheet metal.
- If using brass screws, drive in a steel screw of the same size first to form the thread. The brass screw will then go in more easily and you are less likely to damage the soft head.

Driving screws
A clearance hole is bored in the part being screwed in place. This hole is just large enough in diameter ('d' in the diagrams) to allow the screw to pass through without it having to be turned. It ensures that when a screw is driven, the screw thread will not hold the top piece apart from the piece it is being screwed into. For instance, a 10-gauge screw with a shank diameter of 4.9mm needs a clearance hole of 5mm.

A pilot hole is a smaller hole in the receiving piece, usually about 60-70 per cent of the diameter of the clearance hole. The diameter is that of the solid section of the screw thread. Taking a 10-gauge screw, the pilot hole should be 3mm in diameter, say 3.5mm in well seasoned hardwood. Pilot holes ensure the screw will go in straight (essential with hinges) and not follow soft timber grain.

The screwdriver or driver bit you use must fit the screw. If too large, it will have no effect or round the drive on the screw. If too small you may not have the power to drive the screw properly and it will tend to round the central part of the drive, making it difficult to drive. Having said that, a #2 Phillips will drive most cross screws. Set the torque on a cordless driver to just drive the screw home.

Countersinking
If you are using countersunk screws with a head that has a conical underside, form a suitable countersink with a countersinking bit. If not available and appearance is not important, try a large drill bit. The surface diameter should be the same as that of the screw head. Some screws are self-countersinking, with ribs on the underside.

Counterboring
Counterbore when you don't have a screw long enough to go through the top piece or if the screw head is to be sunk well below the surface for safety's sake. Use a drill bit that's slightly larger than the head of the screw to bore to the depth required.


Skew-nailing
When building timber frames it's common to skew-nail, in other words, drive in nails at opposite angles through the sides of framing timbers. These are normally used on edge and to nail from the top would mean using very long (and expensive) nails. Skew-nailing lets you use smaller nails and makes a stronger joint. For a joint to come apart, the nails have to bend as well as pull out. To skew-nail, clamp the timbers together, start the nail square to the timber about one-third to halfway up with a few taps. Once it has grabbed, bend it to about a 45-degree angle and continue nailing.

Nail plates are used mainly for structural work, joining members across a joint. They are hard to hide. The two (or more) pieces are brought together and the plate nailed across the joint. When repeated on the back of the joint, you can form very strong joints that are surprisingly difficult to pull apart.