Other construction techniques

Turning

For details on Turning techniques, see the section on the Wood Lathe

Carving

Ever since humankind discovered that pieces of wood could be shaped for functional reasons (e.g. weapons and cooking implements) or decorative purposes (e.g. artefacts and sacred items), this ancient art has been developing and is still popular today. There is a large assortment of specialised chisels, gouges and timbers available for the enthusiast and expert, and the possibilities are only limited by the carver's imagination. The main forms of carving are relief carving and carving in the round.

Relief carving

Relief is meant to be viewed from one side only and is normally a board or panel. Therefore, it is a relatively thin work piece. The depth to which the background is cut away determines whether the carving is classified as a low or high relief carving

Carving in the round

Carving in the round is fully three-dimensional and is meant to be seen from all sides. Interesting and effective projects that require few resources (i.e. 200 x 75 x 75 pine) are well within the scope of Year 8 students. Moreover, most of these can be completed with just saws, files and drills. Some examples of projects include a hand, a shoe (add real laces later), a musical instrument, a head, totem poles, an ear, a claw hammer removing a nail, an axe in a tree stump, a seal, a cat (or other animal) and, maybe, a length of chain (four or five links). All of these ideas can be produced from one piece of timber that is not cut or rejoined. Leave a spare 50 mm of timber at the bottom for holding in a vice.

Door detail from an alderman's office, Sydney Town Hall.

Designed by David McBeath, 1878, red cedar. Collection: City of Sydney photograph© Brenton McGeachie, courtesy Historic Houses Trust.

Inlaying

Inlays for decorative contrast were originally narrow, straight or curved strips of wood, bone, ivory, brass, silver, mother-of-pearl or tortoiseshell set into the timber's surface. More elaborate floral and pictorial designs or scroll patterns developed into an art form, which is believed

to have spread through Europe from Persia and India. This art form reached its peak in the seventeenth and eighteenth centuries. Typical examples of inlay include a simple stringing line of one narrow strip of wood round a lid, herringbone edge banding (many designs, patterns and widths are available) and centre inlay motifs

Inlay - stringing

Planing stringing flush

Marquetry

Marquetry (also spelled as marqueterie; from the French marqueter, to varigate) is the art and craft of applying pieces of veneer to a structure to form decorative patterns, designs or pictures.

Most modern marquetry consists of making pictures that cover a whole surface (including the border) using the natural colours and figure of wood to depict materials, tones and textures. A good idea is to make a collection of veneers and then plan the design so that it uses the veneers to best advantage.

An example of marquetry

Veneering

The following processes involve decorating the surface of timber by gluing thin sheet wood (veneers) to a backing or core. The main advantage of veneers is that they allow effects to be created that are not possible in solid wood. An important point to consider is the increasing scarcity of finely figured timbers. Cutting them into veneers means that the supply goes much further.

Veneers can be produced three ways: rotary peeled, sliced or sawn.

Rotary peeled veneers

An appropriate log is cut to length, soaked to soften it then mounted on a large lathe. As the log is rotated, a long blade is pushed against it, moving in a little with every turn so as to maintain an even and continuous sheet of veneer, (just like a pencil sharpener). This is tangential cutting and produces an interesting wavy grained effect. The veneer is then cut to size and dried (much like the plywood manufacturing process). For a slightly different grain effect, the log can be offset in the lathe; this gives the effect of repetitive waves and lines.

Sliced veneers

Logs are selectively cut into flitches then, depending on their grain figure, sliced tangentially (back cut) or radially (quarter cut). The flitch is mounted on a moving frame that reciprocates passing a blade (like a bacon slicer) to produce the similar veneer leaves. Because each leaf is similar, when they are dry they are numbered and bundled together in multiples of four up to 32, which allows for quartering (explained further on). Depending on how the flitch is sliced, the following grain effects can be produced: medullary ray figure, fiddleback, flame, ribbon and birds eye.

Sawn veneers

Since the eighteenth century, when slicing machines became available, this type of veneer has become less common because of the waste due to the kerf of the saw, even though blades are thin. Nowadays, sawn veneers are only used for timbers that are difficult to slice (like some burls, crotches, stumps and roots) or when thicker veneers of up to 3 mm are required.

Tabletops, wardrobe doors, door and wall panels, and sideboard tops and ends all offer a surface that is large enough to veneer and, therefore, display aesthetic patterning. Basic effects can be created by using sequential sliced veneer leaves to show book matching, quartering, diamond, herringbone and segmenting.

An example of burl veneer

How wood veneer is made

Parquetry

This is like marquetry in that it uses geometric shapes, patterns and motifs. Parquetry uses solid timber pieces rather than thin veneers. The most well-known examples are the apparent three-dimensional cubes, chess boards and flooring.

Intarsia

Intarsia is a woodworking technique that uses varied shapes, sizes, and species of wood fitted together to create a mosaic-like picture with an illusion of depth. Intarsia is created through the selection of different types of wood, using their natural grain pattern and colour (but can involve the use of stains and dyes) to create variations in the pattern. After selecting the specific woods to be used within the pattern, each piece is then individually cut, shaped, and finished. Sometimes areas of the pattern are raised to create more depth. Once the individual pieces are complete, they are fitted together like a jig-saw puzzle and glued to a wooden backer-board, cut to the outline of the pattern, often with the intention of creating a three-dimensional effect

An example of Intarsia. Note the 3 dimensional effect

Cutting and laying veneer, marquetry or parquetry

Cutting veneers, especially fine or curved shapes across the grain, requires practice. Veneer cutting knives (preferably with a ground edge on one side only) are best to use as they can give a vertically cut edge that will butt up to the next piece more accurately. For straight lines, always use a safety rule. As a picture, or joins, is made, tape along the edges with Sellotape (easy to see the join). The best core or base to use is a non flexing manufactured board as it has very little expansion or contraction due to moisture change.

Ensure that there is no dust or specks of grit on the joining materials and have clamps, clean white paper, a caul (basically a solid top to clamp over the drying veneers), PVA glue and a small rubber roller available to work with . Animal glue can be used with a veneering hammer to scrape out air bubbles or excess glue and a hot iron to remelt glue as it cools and rehardens . This method is not fully described here.

To lay veneers, use the roller to evenly apply a thin smear of glue over both surfaces (this will slightly expand the veneers and help hide any gaps). Next, position the veneers and add a layer of greaseproof paper to prevent staining and excess glue sticking to the caul. Clamp to keep the veneers under pressure until they dry. In an industrial environment, it only takes a few minutes for the glue to dry because heated presses are used. Another method of pressing is by using a large envelope of neoprene (wet suit material) to fit the project in. Once the project is inside the envelope, seal the open section and apply a vacuum pump to suck out the air. This envelope can also be heated to hasten the curing time. When dry, the tape is gently peeled back and removed. A hair dryer may need to be used during this process to soften the tape adhesion and prevent small pieces of veneer from lifting

Inlay bandings

Strips range in width from 2 mm to 50 mm and are generally about 1 mm thick.

The method of working is as follows:

Grooves in which the bands will be glued are marked parallel to and equidistant from the edges of the work with a cutting gauge (ground edge of blade facing inwards). If a marking or mortise gauge is used, the conical spurs, which make a V-shaped mark, must be sharpened with a fine file so that the outside edges of the grooves will be cut square to the face of the work. Gauge marks must not run beyond the required dimensions of the groove.

Waste is cut out with a chisel used ground side down and the groove is cleaned out with a scratch stock. Bands, mitred at the corners, should be an accurate press fit and flush with the surface or the thickness of a fine shaving above. If the fit is too tight, take a fine shaving off the edge of the banding in preference to widening the groove. If the inlay is below the surface, the whole surface of the work will need to be planed down level with it: if only the area near the inlay is planed, this will show when the work is polished.

Glue the bands in the grooves, pressing carefully into place by hand. If necessary, tap or rub lightly with a hammer to exclude air bubbles. Wipe off surplus glue with a wet cloth. If the inlay tends to lift, glue a piece of paper over the whole area and leave to set.
When the glue has set, tear off the paper and chisel away any lumps of surplus glue before cleaning off with a cabinet scraper.

Centre inlays

Inlays can be made up of squares, diamonds, rectangles and curved shapes, and can be used as centrepieces. These are glued into a recess then cleaned off and finished as for strip inlays.

Handsome designs are achieved by using timbers of different grains and contrasting colours- either natural or dyed. Popular central motifs can be purchased already made up and ready to insert.

Place the inlay in position, matching the grain direction with that of the work, and mark accurately around the outside with a sharp pencil. Cut with a sharp chisel or knife about 1 mm inside the mark.
Chisel out waste to the required depth then carefully trim to the marked line, testing frequently for fit. Work as far as possible with the grain. A chisel ground and sharpened to a V point is useful for cleaning out acute angles.
Glue the inlay into the recess, clean off and finish as for a strip inlay.

Inlay banding on a mitred corner

Hints for glues for inlays

All inlay work is simplified by using the right type of glue. Note that:

PVA glue is convenient to use and is satisfactory if allowed to become tacky before the inlay is inserted. For best adhesion, apply glue to both parts to be joined.
Animal glue is excellent as it does not stain and sets quickly enough to hold the work in position without pressure. However, it must be freshly made, hot and not too thick. To correct imperfect adhesion, it can be remelted with a hot iron.

Describe the process involved in applying and finishing veneer on the face and edges of a manufactured board.

Contact Adhesive method

Select a suitable veneer and match grain ensuring the grain runs in a suitable direction.
Apply contact adhesive to both the board and the underside of the veneer and wait until it is tack dry.
Bring the veneer together with the board and apply firm pressure. Use a scraper to remove any bubbles and apply pressure.
Once the adhesive is set, sand in the direction of the grain with progressively finer sand paper.
Dust down, select a suitable finish and apply a minimum of three coats.
Allow to dry and sand between coats.

Glue Method (similar to ours)

To lay veneers, use the roller to evenly apply a thin smear of glue over both surfaces (this will slightly expand the veneers and help hide any gaps).
Next, position the veneers and add a layer of greaseproof paper to prevent staining and excess glue sticking to the caul.
Clamp to keep the veneers under pressure until they dry.
Once the adhesive is set, sand in the direction of the grain with progressively finer sand paper.
Dust down, select a suitable finish and apply a minimum of three coats.
Allow to dry and sand between coats.

Laminating and bending

To make curved shapes in wood, you can cut the curve from solid timber, mould the shape in laminated wood, bend a piece of solid wood by kerfing, or undertake steam bending. Cutting a curved piece from solid stock wastes material, and the piece is usually not very strong due to short end grain.

Laminated wood consists of a number of layers of parallel-grained timber, thin enough to be bent, that are glued together face to face then formed and clamped in or around a mould. Note that gluing timber edge to edge is not classified as 'laminating' but as 'widening'.

Laminated wood is used where the grain runs parallel to the length of the timber as, for example, in the frames of older-style tennis and squash racquets. You may also see it in structural beams and arches, skate boards, snow and water skis, boat frames and hulls, piano key lids and guitars; these are only a few items that can be made this way For some specialised work, industry produces what is known as 'improved wood' by impregnating wood laminates with plastic to improve density, toughness and workability. Some products made from improved wood are aeroplane propellers, golf club heads and knife handles. Laminated wood is stronger than solid timber because defects, such as knots and splits, are localised to individual layers and their weakening effect is therefore reduced. On the basis of strength-to-weight ratio, laminated wood is considerably stronger than steel.

Both hardwoods and softwoods are suitable for laminating, though hardwoods generally will bend better. The timber should be straight-grained, preferably free from knots and other defects, and uniform in thickness. 'Greasy' timbers, such as teak, should be cross-sanded to aid glue adhesion.

Glues for laminating must have a working time that will allow pieces to be positioned and cramped before setting takes place. There are two types of mould used in laminating: a two part mould (Fig. 3) or a single non-flexing form. Vacuum moulding may be used to press the job to the form.

Figure 1. Peanut chair by Marc Newson 1988

Kerfing involves making a certain number of partial cuts in solid timber. This weakens the timber enough to allow the weakened part to be bent round a former. The required curve can only be produced after you have experimented with the thickness of each cut, its depth and the amount of cuts needed. A single kerfed piece of wood is fine when only the outsides are seen. Two kerfed pieces can be glued back to back if necessary (Fig. 4).

Steam bending is the use of steam on certain timbers, which are susceptible to the softening effect of steam, to achieve permanent bends in the construction of projects. Suitable timbers for this are ash, beech, birch, elm, hickory, oak, walnut and yew.

Probably the most well-known use of this treatment is the Bentwood chair by Thonet, which is created from beech that has been steam bent. This piece is almost 150 years old and has hardly changed in appearance to those made today (Fig. 2). The steam bending process involves heating strips of timber in a tube-like container, which has an attached supply of steam from a boiler at one end and an exit for pressure at the other. Soaking time for the timber is about one hour for wood that is 25 mm thick. As the strips of timber are removed (with thick gloves) they must be quickly placed around a former before they cool. Generally, a stainless steel strap is placed round the outer section of the strip to hold it clamped until it dries and takes on its new shape (Fig. 4). Note: There is always a small amount of springback, which must be allowed for when designing the former.

Figure 2. The Bentwood Chair

Figure 3. Two part mould for laminating veneers

Figure 4. Kerfing - single and back to back

Describe a process to produce a laminated curved component for a rocking chair.

Timber strips of a straight grained species are to be ripped into thin sections on the table saw (this is to be done by the teacher)
Construct a former or template of the desired curve allowing for the thickness of the material to be laminated and bent. Also ensure that the template allows for “springback” in the lamination
Assemble the strips to be laminated ensuring the grain is all running in the same direction and dry clamp to check curve. Number each strip so that they are reassembled in an identical fashion when glued
Glue one side of each strip and assemble strips
Clamp strips into template, use grease proof paper on template to ensure lamination does not adhere to template
Remove excess glue with a damp cloth
Check to ensure that lamination is appropriately curved, square and not twisted
Leave to dry
Remove clamps
Finish piece as appropriate

Routing

The router is a vertically encased high-speed motor with a collet chuck at the end. An adjustable low friction baseplate gives the depth of cut for the router bits. Routers are machines that need two hands for operation and come with a straight guide and template chaser parts (see Fig. 1). As one of the most versatile woodworking machines, the router can cut along any grain direction, be used on a variety of materials, can cut a large choice of joints like rebates, trenches, grooves and dovetails, cut recesses and sign writing-plus a host of decorative work.

Methods of using routers

When setting the router up for use, insert the correct cutting bit and set the correct required depth of cut. You need to be careful when undertaking both of these activities and ensure that the cutting bit and depth of cut are locked firmly or it could result in the bit working lower into the wood. Ensure that the bit is fully in the collet chuck then pull out about 2 mm, and if reducing from a 12.5 mm chuck to a 6.35 mm bit shank ensure that the correct spacer is being used.

Plunge routers have the added advantage that they can be positioned then switched on and plunged accurately to a preset depth, which is very useful when the part being cut does not come to the edge of the wood. They also allow for the baseplate to be easily moved out of the way when changing bits.

Hint All routers turn clockwise as viewed from the top and rotate about 10 times faster than a portable power drill. (This is why a drill cannot be used as a router.) If a router was set up with a cutting bit and introduced to a piece of timber to be pushed and cut freehand, it would always tend to veer off to the left. This is important as you can always work out where to place a guide to help maintain a straight cut.

Guiding the router

There are five ways to guide a router:

Using a clamped guide for the router to run along. Ensure this type of guide extends at least 100 mm before and after the wood being cut so that the router is straight when it enters and exits. The guide will be clamped on the left of the router as it is pushed.
Using the guide attached to the router base requires that the guide be on the right side of the router so that it remains against an accurate edge of the timber. Some people fix a wooden extension to this type of guide for extra accuracy.
A pilot-tipped bearing on a bit will allow cuts like fancy edging, rebating and trim flushing to be achieved because there is a ball bearing, of various sizes for different effects, mounted underneath the cutter. It is the bearing that rests against the timber and runs along it, thereby maintaining a faithful shape. If stopping at a corner in a piece of wood, approach it very slowly so that the bearing does not roll round the corner. If proceeding with the cut round the corner, be aware that three-quarters of the whole router may be unsupported and wobble. Before starting a cut, always check that the bearing is adjusted to wholly rest against the timber, and that it is in good condition and running smoothly when spun by hand. Always travel in an anti-clockwise direction when routing round the outside of an object but go clockwise if routing round an internal panel; for example, running a rebate for a glass insert in a small table.
A template chaser is a system used when shapes (generally of a curved nature) are being reproduced repetitively. This system is a positive guiding device that does not allow the cutter bit to wander off in any direction other than that which is required. A flanged tube is mounted under the baseplate and a special jig is made that allows the tube to only run along it for a preset path and distance. The cutter protrudes through the middle of the tube routing as the tube is moved and the whole jig is clamped on to the project.
Freehand routing is used to rout out an area of wood to a certain depth. It could be used for inlay work, relief or recessed work, and lettering. If routing out an area larger than the router baseplate, always start in the middle and work out. If you prefer, routers may be pulled towards you rather than pushed away Remember, however, that the router's tendency to drift left will now be reversed so it will drift right as you view it-make allowances accordingly.

Routers can be used with other apparatus like dovetailing machines. These take considerable time to set up, which is fine for multiple use on identical joints.

Router bits (cutters)

The most popular material for the cutting tips of a bit is tungsten because it is long-lasting and not too costly. High speed steel (HSS) is cheaper but blunts more quickly on hardwoods. Solid tungsten can be used for small bits, but is very expensive. Ceramic cutters are available-but normally only in industrial situations as they are brittle and very expensive. The shank sizes are mainly 1/4 inch (6.35 mm) or 1/2 inch (12.7 mm) but there are a few 3/8 inch (9.52 mm) and 3/4 inch (19.05 mm)

General uses for routers

Factors that affect cutting are:

how fast the feed is
the depth of cut
the size of the bit plus its sharpness
the moisture content and hardness of the wood.

Experience and the sound that the router makes will indicate whether you should feed more slowly or faster or take two cuts (half-depth followed by full depth). If the feed is too slow, it might burn the timber; if it is too fast it might leave rough edges. To avoid splintering when you are exiting an edge, scrap wood should be clamped at the same height to protect the joint.

Before plugging in and using the router, familiarise yourself with the grip and practise switching it on and off, as well as locking and unlocking the plunger. Practise on scrap wood if you are unsure of how a cut will look. Be certain that the work is securely clamped; two clamps are far better than one, which could spin during the routing operation. When starting a router, make sure your feet are in a well-balanced position and hold the router firmly because initial torque will tend to twist it out of your hands. The soft-start models avoid this problem by initially lowering the current surge to the router. In general, the router should be moved along the job so that the speed of the motor does not slow by more than a third.

Ensure that the bit is clear of the wood before starting the router. When routing along an edge, remember that half of the router weight is hanging out over the edge of the work piece so apply more downward pressure on the side of the router that is resting on the wood.

Specific safety tips for routers

Always wear PPE equipment for eyes, ears and breathing.
When you have finished making a pass, if the bit is still within the wood (for example, as with a stopped housing) move it back about two millimetres and keep it perfectly still until the motor is stationary before lifting it out of the wood. Once this is done, face the bit away from you, rest it on the bench, switch off the machine and remove the power plug. If the bit is clear of the wood, lift it, switch the machine off and hold it with the bit away from you until it is stationary.
Use power sockets suspended from the ceiling, if possible, to avoid trailing extension cords. Ensure that the cord is in no danger of being caught in the router; drape it clear.
When removing or changing bits, be aware that they are very sharp.