Basics of Woodworking
Adhesives, nails and screws
There are so many different ways of joining wood together that even the most experienced woodworkers can not master then all. Most projects do not require complicated joints such as dovetails and mortise and tenons.
Before making joints requiring adhesives, nails or screws, check with the tables in this chapter to find the right type for the job.
Adhesives:
Choosing the right one for the job
Adhesives are widely used not only to glue wood to wood joints but also to join materials such as rubber, metal, glass, fabric and even stone. The chart below shows a wide variety of glues, but for general woodworking, only two or three types are normally required. In choosing an adhesive keep in mind several factors:
1. Choose the glue that is suitable for the materials to be joined. PVA woodworking glue is best for ordinary wood to wood joints but a strong epoxy adhesive may be required to bond glass to glass or wood to metal.
2. Consider the strength of the joint: the corner mitre joint of a picture frame does not have to be particularly strong, so general-purpose PVA adhesive is quite adequate. The dowelled framework of chairs, on the other hand, has to stand up to a lot of strain, and a stronger synthetic resin adhesive is more suitable.
3. Always keep in mind the site of the glued joints. The most important consideration is moisture. For projects that will undergo exposure to rain or water, such as garden furniture or kitchen and bathroom articles, use a waterproof adhesive such as a synthetic resin.
4. The basic tool kit should include a medium-sized container of general purpose PVA woodworking glue, small amounts of epoxy cement for special jobs, and synthetic resin for waterproof joints. A tube of quick-drying cellulose glue for model-making and small repairs is also useful but it is best to buy other adhesives, such as contact cement; for specific jobs. The new, instant glues which bond in seconds should not be used for woodwork; they can be dangerous to use and are not necessary.
Gluing techniques
Read the manufacturer's instructions before using any glue. The surfaces to be glued must be clean, dry and free from grease. Most glues should be applied at room temperature and normal moisture conditions, otherwise they may take longer to set and might not set at all.
Apply the adhesives evenly, usually to only one contact surface, with a brush or a spreader, then clamp the pieces together moderately tightly. Too much glue or too much clamping pressure will result in most of the glue squeezing out on to the wood and the bench below.
Develop good habits when you glue, particularly for large jobs. Mix up only as much glue as is required. Once the glue is applied, carefully clean off the excess glue before it sets. Finally, clean all brushes and applicators immediately so that they are ready for the next time you need them.
| Type | Description | Typical applications | Strength | Water resistance | Which materials |
|---|---|---|---|---|---|
| Animal or Scotch glues | Old-fashioned woodworking adhesive made from hides and bones. Glue is melted in a special glue pot and is then applied hot. It hardens quickly at room temperature. | Formerly used for most woodworking joints. Particularly useful for gluing down veneers because glue can be softened with application of heat, such as an iron, for adjustment or repair of veneer. | Good | Poor | Wood to wood |
| PVA (polyvinylacetate) | White liquid glue available in plastic containers for easy spreading. Clamp work for 20-30 minutes while glue sets. Dries completely hard in 24hours. Dries clear, but wipe off excess glue with a damp cloth before glue sets. | Most versatile woodworking adhesive, used for all interior woodworking joints and repairs. | Good | Fair | Wood, cork, leather,fabric, and paper towood. |
| Synthetic resin | Generally available as powder containing both glue and hardener. Mix with water according to instructions. Work must be clamped for 4-6 hours depending on room temperature. Wipe off excess glue with cloth moistened with warm water after clamping. | Excellent gap-filling properties makes resin glue ideal for loose-fitting joints in furniture making. Also used for boat-building and other outdoor projects. | Excellent | Very Good | Wood to waved |
| Epoxy | Available in pairs of small tubes .Resin and hardener are mixed together before use. Quick-drying type sets in 10 minutes, others in about 6 hours. Avoid contact with skin. Clean with methylated spirit. | Expense limits application to small jobs such as joining metal, glass, ceramics or stone. | Excellent | Excellent | Glues almost everything. Wood, metal, glass or plastic to wood. Metal, glass, plastic, or stone to metal. Glass to glass. |
| Contact cement | Rubber-based adhesive applied to both surfaces and allowed to touch-dry before joining with firm hand pressure. Instant joint means no cramping is required. Surfaces cannot be moved once joined. (New types allow minor adjustment.) Clean with special solvents sold by glue makers or with acetone or nail varnish removers. |
Generally used for fixing plastic laminates to counter tops. Also used for small repairs including woodjoints not subject to much stress. | Good | Good | Glues almost any hard materials, particularly plastics and plastic laminates to wood. |
| Cellulose | Plastic-based adhesive available in small tubes. Dries very quickly, is therefore used for fixing small awkwardly shaped pieces. Dries clear. Remove excess glue immediately with acetone or nail varnish remover. | Used extensively for model building and small household repairs, such as fixing broken china. | Good | Good | Glass, china, plastics to glass. China, plastics to wood. |
Nails and screws
Nails
Nails are available in a variety of sizes, shapes and materials. Unlike screws, which actually grip the wood, nails hold by friction. A nail driven into wood forces the fibres apart, and because of the very tight fit, the friction between the nail and the wood holds the nail in place. If the wood splits, which often happens particularly near the end of a board, there is little friction and therefore little holding power. Oval nails are less likely to split the wood.
Most nails can be bought either by weight or in small individual packages, but it is more economical to buy them loose and store them in labelled boxes or jars. The most useful types and sizes are round or oval wire nails in lengths from about 38 to 63mm and panel pins in lengths from about 19 to 32mm. Buying other types and sizes as necessary will soon give you a good selection.
For most applications, steel nails are suitable, but for projects where these are likely to rust and discolour the wood, use galvanised nails or aluminium nails, although these are not available in as wide a range of sizes.
If in doubt about which type or size of nail to buy, seek the advice of a hardware merchant.
| Nails for general woodworking | ||
|---|---|---|
| Type | Description and use | Generally available lengths (mm) |
| Round wire nail | General purpose steel nail.Usually for rough construction jobs. Larger sizes likely to split thewood. Some sizes available galvanised. | 20-150 |
| Oval wire nail | Used in construction and joinery. Oval shape is lesslikely to split wood. | 20-1501 |
| Lost head nail (round or oval) | For joinery and laying floor boards. Less obtrusive head is either left flush or punched below surface. | 40-75 round 20-150 oval |
| Floorboard nail | Sturdy rectangular section nail used to fix down floorboards. Does not split the wood. | 38-75 |
| Panel pin | Thin nail with very narrow head used in general joinerv and cabinet making for jobs requiring small hidden fixing, such as attaching moulding or cabinet backs. | 12-38 |
| Other useful nails: | ||
| Hardboard nail | Copper-finished nail with extra strength to go through hardboard. Diamond-shaped head is driven into board. | 18-100 |
| Masonry nail | Extra hard nails used for fixing in masonry and concrete. Available in small packages. | 6-30 |
| Tack | Old or "improved" styles. Used to fix fabric, webbing or carpet to wood. | 3-12 |
| Chair nails | Available in brass, bronze, chrome or antique finish. Used as decorative nail in upholstery. | 20-75 |
| Annular nail | Steel nail with fine ridges. Used in joinery where extra holding strength is required. | 25-75 |
| Staple | Used for fixing wire to wood. Particularly for fencing and upholstery. Also available galvanised. | 12-38 |
Screws
Length and gauge
Screws are available in a number of sizes, gauges, materials and head types. The size is specified by the length and the gauge, which is a measure of the shank diameter and is referred to by the number (No.). The larger the number, the heavier the screw.
The most useful sizes range from about 19mm to about 63mm, but there are also many uses for screws as small as 6.5mm in diameter and as long as 152mm. It is often much more economical to buy screws in complete boxes of 200 or in half boxes of 100. They are also sold loose or in packages of ten, when only a small number is needed.
It is important to use the correct length of screw to fix two pieces of wood. It must project far enough into the second piece to have sufficient strength but not extend through the other side.
The tables below lists the use of screws and ways to determine the required lengths.
Materials used for screws
Steel screws are the most common but brass screws, although they are not as strong, are more attractive and do not rust.
Screws are also available with special finishes such as chrome and black japanned, although not in all sizes or head shapes. It is best to check availability with a large hardware shop before planning to use a special screw.
Head types
Countersunk head screws are screwed in so that the head is flush with (countersunk) or slightly below (counterbored) the surface.
Round head screws are used for fixing sheet metal to wood or as a decorative fixing. They are available in steel and also in a black japanned finish or in more expensive brass or chrome finishes. The raised countersunk head is a decorative head used mostly to fix hardware to furniture.
ABOVE, FROM LEFT: The various screw e types available: countersunk, round head. raised countersunk. Phillips head and dome-covered. When measuring a round head screw (below). do not include the head as part of its length.
Slotted and cross-slotted screw heads
Most screws have a single slot for use with ordinary screwdrivers, but where the screwy is difficult to site, the head is often damaged, particularly on the softer brass screws.
Cross-slotted or Phillips head screw heads, for use with special cross-slotted screwdrivers which come in three sizes, are much less likely to be damaged as the screwdriver has a much firmer grip on the screw.
Readily available screw sizes
| Countersunk steel | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Shank numbers | |||||||||
| mm | in | 3 | 4 | 6 | 8 | 10 | 12 | 14 | 16 |
| 9 | 3/8 | x | x | x | |||||
| 12 | 1/2 | x | x | x | x | ||||
| 15 | 5/8 | x | x | x | x | ||||
| 19 | 3/4 | x | x | x | x | x | x | ||
| 25 | 1 | x | x | x | x | x | x | x | |
| 32 | 1 1/4 | x | x | x | x | x | x | ||
| 38 | 1 1/2 | x | x | x | x | x | x | x | |
| 44 | 1 3/4 | x | x | x | x | x | x | ||
| 50 | 2 | x | x | x | x | x | x | ||
| 57 | 2 1/4 | x | x | x | x | x | |||
| 63 | 2 1/2 | x | x | x | x | x | x | ||
| 76 | 3 | x | x | x | x | x | x | ||
| 8 | 3 1/2 | x | x | x | x | x | |||
| 101 | 4 | x | x | x | x | x | |||
| Countersunk Brass | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Shank numbers | |||||||||
| mm | in | 3 | 4 | 6 | 8 | 10 | 12 | 14 | 16 |
| 9 | 3/8 | x | x | x | |||||
| 12 | 1/2 | x | x | x | x | ||||
| 15 | 5/8 | x | x | x | x | ||||
| 19 | 3/4 | x | x | x | |||||
| 25 | 1 | x | x | x | x | x | |||
| 32 | 1 1/4 | x | x | x | x | ||||
| 38 | 1 1/2 | x | x | x | x | x |
|||
| 44 | 1 3/4 | x | x | x | |||||
| 50 | 2 | x | x | x | x | x |
|||
| 63 | 2 1/2 | x | x | x | x | ||||
| 76 | 3 | x | x | x | x | ||||
| Round Head | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Shank numbers | |||||||||
| mm | in | 3 | 4 | 6 | 8 | 10 | 12 | 14 | 16 |
| 19 | 3/4 | x | x | x | x | ||||
| 25 | 1 | x | x | x | x | x | |||
| 32 | 1 1/4 | x | x | x | x | ||||
| 38 | 1 1/2 | x | x | x | x | ||||
| 50 | 2 | x | x | x | x | x | |||
| 63 | 2 1/2 | x | x | x | x | ||||
| 76 | 3 | x | x | ||||||
