The diagrams below illustrate a selection of the most common nails used in the woodworking trades today. However, there are numerous other special purpose nails such as underlay nails, plasterboard nails, process nails and collated nails of various types which are used in portable nailers.
Bullet head nails are the ordinary general purpose nails used for fixing timber framing, mouldings, flooring and general cabinet work. Galvanised nails are available for external use.
Flat-head nails are used for fastening thin boards such as case timber, where the nail head does not have to be punched and filled for appearance and where the larger flat head might prevent the nail from pulling through. Small flat head nails are often sold as wallboard nails.
Particleboard nails have been designed specially for nailing particle board. The twisted thread provides more grip in the flaky structure of particle board than bullet head nails.
Clouts are heavy duty flat head nails, usually galvanised for external use such as fixing sheets of flat galvanised iron.
Flex sheet nails are generally used for fixing fibre cement sheets to framework. The head helps to prevent the nail from pulling through the fibrous sheet.
Hardboard nails are used for fixing high density compressed boards such as masonite to framing. The tapered head is designed for ease of entry into the hard surface of the sheet.
Brads or panel pins are like small bullet head nails and are used for very fine nailing, generally where the head of the nail is to be punched and filled or where it can be concealed in a random groove or other panel feature.
Upholstery nails are available in a range of colours and are used for visible fastening of leather and fabrics to the wooden frames of covered furniture.
The diagrams which follow illustrate the nail positions for three commonly used methods of nailing timber.
Parallel nailing can be used satisfactorily in timber which grips the nails very well, such as hardwood. This nailing method which is illustrated below-left, may not provide sufficient joint strength if used in very soft timber.
Dovetail nailing or splay nailing shown below-centre provides greater strength in the nailed joint than parallel nailing because nails which are not parallel to each other are more difficult to withdraw.
Skew nailing illustrated below-right is used where timber thickness or inaccessibility prevents other methods from being used.
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| Parallel Nailing | Dovetail Nailing | Skew Nailing |
Before leaving this page, think of what you've just been reading, and test yourself with these questions.
[[ mc /f ][ Which nail would be most suitable for fixing masonite to framing? ][ Hardboard nails ][ * Particleboard nails ][ * Clouts ][ * Flat-head nails ][ Hardboard nails have a tapered head to easily enter the hard sheet. ]]
[[ mc /f ][ Which nail is suited for most general fixing uses? ][ Bullet head nails ][ * Flat-head nails ][ * Flex sheet nails ][ * Brads ][ Bullet head nails are a general purpose nail used for anything from flooring to cabinet work. ]]
[[ mc /f ][ Which nail is designed with a twisted thread to provide extra grip? ][ Particleboard nails ][ * Flex sheet nails ][ * Hardboard nails ][ * Clouts ][ Particleboard nails have a twisted thread to grip the flaky structure of particleboard better. ]]
[[ mm /f ][ Match the nailing technique with its description: ][ Parallel nailing ~ Relies only on the grip of the timber for joint strength ][ Dovetail nailing ~ Nails are nailed in at an angle to each other for extra strength ][ Skew nailing ~ Used when other techniques are impossible due to timber thickness or inaccessibility ][ Parallel nailing can only rely on the timber's grip on the nails, dovetail nailing provides extra grip due to the opposing angles, and skew nailing is for when the other techniques are not possible. ]]
[[ sh ][ SCREWS ]]There are many screw types on the market today, from traditional wood screws to a large range of screws manufactured for specific uses.
The diagrams which follow illustrate some of the most common types of screws used in the woodworking trades and building industry.
The choice of head type will usually be determined by the application for which the screw is to be used.
Countersunk head screws are used where the head of the screw is to be flush with the surface of the material being fixed. A countersinking bit is generally used to form the tapered hole (countersink) that the head fits into.
Raised head screws are often used for decorative purposes such as fittings and handles and for fixing sheets in conjunction with a cup washer.
Round head screws are generally used where the material being fixed is too thin to be countersunk.
The type of slot in the screw head will determine the type of driver to be used. A correctly fitting driver tip should be selected to prevent damage to the screw slot. The illustrations below show the two most common types.
Slotted screw heads are the traditional type used on conventional wood screws as well as other types of screws.
Phillips head screws with their cross shaped slot are probably the most common type of screw used today. The driver tip selected should fit snugly into the slot without rotational movement or play.
The illustrations below show the common types of threads on screws which are used for general woodworking applications.
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Conventional wood screws are used for fixing to solid timber. A clearance hole is required for the unthreaded shank of the screw to prevent binding in the material being fastened (as shown below). Long thread screws are also used for fixing to solid timber and are fully threaded for additional holding power. Particleboard screws feature a full length thread which provides extra grip in the flaky structure of particleboard and other manufactured boards such as medium density fibreboard (MDF). A clearance hole (as shown below) may also be required. Short thread particleboard screws generally do not require a clearance hole for the unthreaded part of the screw. |
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The illustration below shows the parts of a wood screw and the screw holes that are generally required to be drilled in the material.
A pilot hole the diameter of the screw’s core is drilled in the base material to allow the screw to cut its own thread.
A clearance hole slightly larger than the shank of the screw is drilled through the material being fastened to prevent binding.
Before leaving this page, think of what you've just been reading, and test yourself with these questions.
[[ tr /f ][ What screw head is often used for decorative purposes? ][ raised ][ Raised heads are often used for decorative purposes. ]]
[[ tr /f ][ The two most common types of screw slot heads are slotted and what other type? ][ phillips ][ Slotted and phillips head screws are the two most common slot heads. ]]
[[ mc /f ][ Which screw would be used when joining timber, but requires extra strength? ][ Long thread screws ][ * Conventional wood screws ][ * Particleboard screws ][ * Short thread screws ][ Conventional wood and long thread screws would both work for general timber joining, however the long thread screw has more thread and therefore more strength. ]]
[[ sh ][ ADHESIVES ]]Bonding of two porous substances was once attributed solely to the keying of adhesive around the fibres and into the crevices of the materials. Scientific studies now suggest that this might account for only a small part of the joint strength and that molecular attraction is primarily responsible for adhesion.
There are many types of adhesives available today but many are not suitable for use in the school workshop. Some types require strictly controlled temperature or special apparatus for application or curing while other special purpose adhesives may have a very limited shelf life.
It is necessary to know the characteristics of adhesives so that the most suitable type can be chosen for a particular job. The adhesives listed below are some of the more common products used in industry today.
Polyvinyl Acetate (PVA) is a white, ready to use glue produced by reacting acetylene with acetic acid. PVA is not water resistant but does resist fungi and bacteria, has excellent gap filling qualities, is non-staining and not flammable.
It is a good general purpose glue but will not bond a non-porous surface to any other, for example metal to wood. PVA has unlimited shelf life in sealed plastic containers and a cramping (pressing) time of up to four hours depending on air temperature and humidity.
Contact glue is a synthetic rubber based adhesive. It is mostly used to bond plastic laminate to manufactured boards, for example in kitchen bench tops. It can also be used to bond flexible rubber and some plastic materials to wood and to each other.
Adhesive is applied to both surfaces and allowed to become touch dry before bringing the surfaces together. Bonding takes place immediately on contact. Strength increases as the glue cures over several days. No cramping is necessary and shelf life is approximately one year.
These adhesives are thermo-setting resins which are hardened by the addition of a catalyst. The setting action is one of chemical change and while the process may be accelerated by heat, the plastic glue cannot be softened by heat once it has set.
Urea Formaldehyde is an adhesive used widely in industry and is available in powder and liquid forms. Where exceptionally long open working times are required, resin may be applied to one surface and hardener to the other so that setting does not take place until the parts are brought together.
Urea formaldehyde is generally used in the manufacture of sheet materials such as plywood, standard particleboard and medium density fibreboard.
Phenol Formaldehyde is a dark coloured adhesive used mainly in the manufacture of marine plywood and other building materials where moisture resistance is very important.
Melamine Formaldehyde is a waterproof, heat resistant, non-staining adhesive, prepared for use by mixing the powdered resin with water and then adding the liquid hardener. Separate application of the resin and hardener is possible, making melamine formaldehyde ideally suited to caravan construction and boat building.
Resorcinol Formaldehyde is supplied as a dark coloured liquid usually with a powdered hardener. It is generally accepted as the best adhesive for the construction of boats and aircraft where bonding of wood materials is necessary and wherever an extremely durable glue is required.
Resorcinol formaldehyde has outstanding resistance to moisture, cold, heat, solvents, mould or fungi. Its only disadvantage is that the dark colour stains timber.
These adhesives are also of the two part type with resin and hardener. Epoxy resin glues are waterproof and very strong. They will bond wood to wood, metal to metal, rubber to metal, glass to glass, glass to metal and thermo setting plastics to each other.
Normal setting time for most epoxy resin adhesives is about 8 hours but this can be reduced by heating. There are also quick setting varieties on the market that will begin to set in a few minutes.
Before leaving this page, think of what you've just been reading, and test yourself with these questions.
[[ mc /f ][ Which glue type is a two part glue where the addition of heat accelerates the setting, and then once set resists heat? ][ Formaldehyde adhesive ][ * Polyvinyl acetate ][ * Contact glue ][ * Epoxy resin ][ Formaldehyde adhesives are two part and set with heat. ]]
[[ mc /f ][ Which glue type resists bacteria, is not flammable, but has difficulty bonding glass to metal? ][ Polyvinyl acetate ][ * Formaldehyde adhesive ][ * Contact glue ][ * Epoxy resin ][ Polyvinyl acetate (PVA) has an unlimited shelf life, resists fungi and bacteria, has excellent gap filling, and is non-staining and non-flammable. ]]
[[ mc /f ][ Which of these is not a type of formaldehyde adhesive? ][ Acetylene formaldehyde ][ * Urea formaldehyde ][ * Phenol formaldehyde ][ * Resorcinal formaldehyde ][ Urea, phenol, melamine, and resorcinol are the 4 types of formaldehyde adhesives. ]]
[[ sh ][ ABRASIVES ]]Abrasive paper used for smoothing timber and other wood products, consists of abrasive materials in the form of grit, bonded to a paper backing. Sheet abrasive materials are often loosely referred to as ‘sandpaper’, hence the term ‘sanding’ which is the action of rubbing a surface with abrasive paper.
Glass paper is a traditional abrasive paper that has been used in woodworking for centuries. It is made from crushed glass, quartz or flint which is glued to stiff brown paper. It is not waterproof and is generally used for light hand sanding.
Garnet paper is similar to glass paper except that the abrasive material is made from garnet, a semi-precious stone which is reddish-brown in colour.
Garnet is of medium hardness and toughness and because it has a tendency to fracture, forms new cutting edges as it is being used. Garnet paper is available in rolls usually 100mm and 150mm in width.
Silicon carbide is manufactured from coke and sand fused together in a furnace and then ground to a fine grit. It is a shiny black synthetic abrasive which is brittle and fractures into sharp wedge-shaped slivers.
It is very hard and is generally bonded to waterproof sheets with a waterproof adhesive. Silicon carbide sheets are usually called ‘wet and dry’ abrasive paper.
Aluminium oxide is manufactured from bauxite, iron filings and coke fused together in a furnace and then ground. It is usually a grey-brown colour, extremely tough and resistant to normal wear.
This abrasive is particularly suited to heavy duty machine sanding. Most abrasive discs used on portable power sanders are made from aluminium oxide.
After crushing, abrasive materials are sieved through accurately woven silk screens. The size of the mesh is determined by the number of openings per given area and this in turn determines the grade of the abrasive.
For example, a sieve which has 80x80 holes per given area would be graded as 80 grit. Grades can be generally described as very coarse, coarse, medium, fine and very fine. Abrasive grit can range from 20 (coarsest) to 1200 (finest).
The most common grades used for bench work and general woodworking applications are listed below:
Glass paper and garnet paper are used mainly in woodworking applications for the preparation of surfaces to be finished with paint, varnish or other materials. Both abrasive papers are suitable for hand sanding but garnet paper is preferable for use on an orbital sander because it is more durable than glasspaper.
Silicon carbide and aluminium oxide are usually bonded to waterproof paper or fabrics in the manufacture of a range of abrasive sheet materials. These abrasives are suitable for use on a variety of surfaces such as wood, plastics, metal, and paint.
Water is used with wet-and-dry abrasive paper to prevent waste material in the form of dust from clogging the grit. The water washes the waste away enabling the abrasive grit to contact the surface being sanded.
Aluminium oxide is suitable for heavy duty machine sanding such as sanding discs, belt sanders and in floor sanding machines.
Aluminium oxide and silicon carbide are both used in the manufacture of abrasive wheels (emery wheels). Abrasive wheels are generally used for tool sharpening and general metal grinding.
Before leaving this page, think of what you've just been reading, and test yourself with these questions.
[[ mr /f /r ][ Which of the four types of abrasive paper material has tendencies to fracture? ][ Garnet ][ Silicon ][ * Glass ][ * Aluminium ][ Garnet and silicon carbide both fracture under pressure, forming new cutting edges. ]]
[[ mc /f /r ][ An abrasive paper graded at 60 grit had how many holes in the sieve during production? ][ 60x60 ][ * 30x2 ][ * 30x30 ][ *60x1 ][ *30+30 ][ 60x60 produces a 60 grit abrasive. ]]
[[ mr /f /r ][ Which abrasive papers are classified as wet-and-dry? ][ Silicone carbide ][ Aluminium oxide ][ * Glass ][ * Garnet][ Silicone carbide and aluminium oxide abrasive paper are classified as wet-and-dry, and when used with water help prevent waste dust clogging the grit. ]]
[[ sh ][ WOOD FINISHING ]]The two basic stages of wood finishing are surface preparation and the application of finishing materials.
Surface preparation is a very important part of wood finishing. The method used will depend on the type of wood or wood product that is to be finished and the type of finish required.
Refer to the previous section for information on abrasive papers. Usually garnet paper or glasspaper will be used for hand sanding in the wood shop. Abrasive papers should be used in conjunction with a sanding block when hand sanding flat surfaces.
Larger surfaces can be sanded with an orbital sander or a random orbital sander before being finished by hand sanding. Refer to the section on Portable Power Tools for more information about these sanders.
When hand sanding, care must be taken to always sand with the grain, particularly when clear finishing materials are to be used. Scratches in the wood surface caused by sanding across the grain show through a clear finish and spoil the appearance of the finished product.
Most hand sanding operations in the wood shop require the use of a medium grade abrasive paper to remove blemishes from the surface, followed by a fine grade paper to remove any scratches made by the coarser grit on the medium grade paper.
Stoppings, more commonly called ‘putty’ should be used to fill all nail holes and cracks, so that a uniform finish can be obtained. Some of the common types of stoppings are listed below.
Common finishing materials are stain, wood grain fillers, clear finishes and paint.
Items of furniture and other articles are often made from cheap timber and stained to look like more expensive varieties. Stain, if required, is applied after the surface is sanded to colour the wood before the application of a clear finish.
Wood stains are available in a number of natural timber colours and other decorative colours. Stains are manufactured with either a water base or a spirit base.
The most popular clear varnishes used today are one part polyurethane plastics, usually available in gloss, satin and matte finishes.
The first coat should be thin and evenly brushed, rolled or sprayed over the surface to be finished. This coat causes the wood cells on the outer surface to swell and also sets the loose fibres on the surface, usually resulting in a rough or gritty surface when the coat is dry.
A light sand with a very fine abrasive paper will provide a smooth surface in preparation for the second coat. If a third coat is required the surface should be lightly sanded first.
Wood grain fillers are sometimes used to fill the pores of open grained timber to provide a smoother base for application of the clear finishing material. Ready to use wood grain fillers are available in a range of popular timber colours.
Grain filler is usually applied by rubbing it into the grain with a hessian pad after firstly applying a thin coat of clear sealer to the timber and allowing it to dry. Any excess is wiped off with a clean cloth, leaving the filler in the pores.
Wood grain filler should be allowed to dry thoroughly before applying a coat of clear finishing material. For timber that is to be stained, the filler should be applied after the stain.
Paint can be classified as water based or oil based in either exterior or interior quality.
Oil based paints are thinned and brushes cleaned with mineral turpentine.
Water based paints are thinned, when necessary, with a little water and brushes wash out easily in cold water.
New timber requires a first coat of special paint called primer, then an undercoat followed by the finish coat. Some plastic paints (usually water based) do not require an undercoat.
Before leaving this page, think of what you've just been reading, and test yourself with these questions.
[[ so /f ][ Sort these steps in order for the finishing of a new timber cabinet: ][ Sanding ][ Powder mix stopping ][ Primer ][ Undercoat ][ Finish coat ][ The correct order is sanding > stopping > primer > undercoat > finish coat. ]]
[[ mc /f /r ][ Which of these substances are used to thin oil based paint? ][ Mineral turpentine ][ * Water ][ * Linseed oil ][ * Wax ][ Mineral turpentine is used to thin oil based paint and to clean brushes used in the paint. ]]
[[ mc /f ][ To get a nicer wood look, before a clear finish is applied, what finishing material should be applied? ][ Wood stain ][ * Paint ][ * Wood grain filler ][ * Just the clear finish ][ Wood staining can be used to make one wood look like a nicer, more expensive wood. ]]