SIMPLE JOINTS

It’s often thought that only elaborate joints give good results in woodwork. It isn’t true.

There are simple ways to join timber, and one of the simplest is the butt joint. It’s easy to make, can be used on natural timber or man-made boards, and it’s neat.

What’s more, given the right adhesive and the right reinforcement, a butt joint can also be strong enough for most purposes.

T he great thing about butt joints is their simplicity. You can use them on any kind of timberor man-made board, provided it isn’t too thin – not under 6mm (Jin). The only problem you will run into is where you are joining chipboard. A special technique is needed here to get the screws to grip, as is explained later.

Although it is possible to simply glue two pieces of wood together, unless you add some kind of reinforcement the result won’t be very strong. So in most cases, the joint should be strengthened with either screws or nails. The question is which? As a rule of thumb, screws will give you a stronger joint than nails. The exception is where you are screwing into the endgrain of natural timber. Here, the screwthread chews up the timber to such an extent that it has almost no fixing value at all. Nails in this case are a much better bet.

Choosing the right adhesive

Even if you are screwing or nailing the joint together, it ought to be glued as well. A PVA woodworking adhesive will do the trick in most jobs, providing a strong and easily achieved fixing. This type of adhesive will not. However, stand up well to either extreme heat or to moisture; the sort of conditions you’ll meet outdoors, or in a kitchen, for example. A urea formaldehyde is the glue to use in this sort of situation. It isn’t as convenient – it comes as a powder that you have to mix with water – but your joints will hold.

Choosing the right joint

There are no hard and fast rules about choosing the best joint for a particular job. It’s really just a case of finding a joint that is neat enough for what you’re making, and strong enough not to fall apart the first time it is used. And as far as strength is concerned, the various kinds of butt joint work equally well.

Marking timber

Butt joints are the simplest of all joints -there’s no complicated chiselling or marking out to worry about – but if the joint is to be both strong and neat you do need to be able to saw wood to length perfectly square.

The first important thing here is the accuracy of your marking out. Examine the piece of wood you want to cut and choose a side and an edge that are particularly flat and smooth. They’re called the face edge and face side.

Next, measure up and press the point of a sharp knife into the face side where you intend to make the cut. Slide a try-square up to the knife, making sure that its stock – the handle – is pressed firmly against the face edge. Then use the knife to score a line across the surface of the timber. Carry this line round all four sides of the wood, always making sure that the try-square’s stock is held against either the face edge or the face side. If you wish, you can run over the knife line with a pencil to make it easier to see- it’s best to sharpen the lead into a chisel shape.

Why not use a pencil for marking out in the first place? There are two reasons. The first is that a knife gives a thinner and therefore more accurate line than even the sharpest pencil. The second is that the knife will cut through the surface layer of the wood, helping the saw to leave a clean, sharp edge.

Sawing square

One of the most useful – and easiest to make.

– aids to sawing is a bench hook. It’ll help you to grip the wood you want to cut, and to protect the surface on which you are working. You can make one up quite easily, by gluing and screwing together pieces of scrap timber hand away from the saw.

As the cut deepens gradually reduce the angle of the saw until it is horizontal. At this point you can continue sawing through until you start cutting into the bench hook. Alternatively, you may find it easier to angle the saw towards you and make a sloping cut down the edge nearest to you. With that done, you can saw through the remaining waste holding the saw horizontally, using the two angled cuts to keep the saw on course.

Whichever method you choose, don’t try to force the saw through the wood – if that seems necessary, then the saw is probably blunt. Save your muscle power for the forward stroke – but concentrate mainly on sawing accurately to your marked line.

Cleaning up cut ends

Once you have cut the wood to length, clean up the end with glasspaper. A good tip is to lay the abrasive flat on a table and work the end of the wood over it with a series of circular strokes, making sure that you keep the wood vertical so you don’t sand the end out of square. If the piece of wood is too unmanageable, wrap the glasspaper round a square piece of scrap wood instead and sand the end of the wood by moving the block to and fro – it’ll help in keeping the end square.

This is a simple way of strengthening any butt joint. All you do is grip the upright piece in a vice or the jaws of a portable work-bench, and glue the horizontal piece on top if it – supporting it with scrap wood to hold the joint square – and then drive in the nails dovetail fashion. If you were to drive the nails in square, there would be more risk that the joint would pull apart. Putting them in at an angle really does add strength.

The only difficulty is that the wood may split. To prevent this, use oval brads lather than round nails, making sure that their thickest part points along the grain. If that doesn’t do the trick, try blunting the point of each nail by driving it into the side of an old hammer. This creates a burr of metal on the point which will cut through the wood fibres rather than parting them.

Once the nails are driven home, punch their heads below the surface using a nail punch, or a large blunt nail. Fill the resulting dents with wood stopping (better on wood than ordinary cellulose filler) and sand smooth.

This is the simplest of all and is one you can use on relatively thin timber. The example shown is for a T-joint, but the method is the same if you want to make an X-joint.

Bring the two pieces of wood together as they will be when joined, and use a pencil to mark the position of the topmost piece on the one underneath. To reinforce the joint, countersunk screws are best, so mark their positions on the top piece of wood, and drill clearance holes the same diameter as the screw’s shank – the unthreaded part – right the way through. The screws should be arranged like the spots on a dice (two screws are shown here, but on a larger joint where more strength is needed five would be better) to help stop the joint twisting out of square. Enlarge the mouths of these holes with a countersink bit to accommodate the screw heads, and clean up any splinters where the drill breaks through the underside of the wood.

Bring the two pieces of wood together again using a piece of scrap wood to keep the top piece level. Then make pilot holes in the lower piece using either a bradawl or a small drill, boring through the clearance holes to make sure they are correctly positioned. Make sure the pilot holes are drilled absolutely vertically, or the screws could pull the joint out of shape. Finally, apply a thin coating of adhesive to both the surfaces to be joined (follow the adhesive manufacturers instructions), position the pieces of wood accurately and, without movug them again, drive home the screws.

Another simple way of holding a butt joint together is to use ordinary corrugated timber connectors. Simply glue the two pieces of wood together, and hammer the connectors in across the joint. Note that they are driven in dovetail fashion – the fixing is stronger that way.

MAKING YOUR OWN BENCH HOOK

This a very useful sawing aid to help grip the wood when cutting. Hook one end over the edge of the workbench and hold the wood against the other end. Make it up from off-cuts and replace when it becomes worn.

You need:.

– a piece of 12mm (Vain) plywood measuring about 250 x 225mm (10 x 9in)

– two pieces of 50 x 25mm ( 2 x 1 in) planed softwood, each about 175mm (7in) long. Glue and screw them together. Use the bench hook the other way up if you’re left-handed.

TIP: SAWING STRAIGHT.

– hold wood firmly against bench hook and start cut on waste side of cutting line with two or three backward cuts.

– decrease angle of the saw blade as cut progresses

– complete cut with saw horizontal, cutting into your bench hook slightly TIP: TO SMOOTH CUT END.

– rub with a circular motion on glasspaper held flat on the workbench, so you don’t round off the corners.

– on large pieces of wood, wrap glasspaper round a block of wood and rub this across the cut end

Because neither nails nor screws hold well in chipboard, how do you hold a butl joint together? The answer is that you do use screws, but to help them grip, you drive them into a chipboard plug. Chipboard plugs are a bit like ordinary wall plugs. In fact, you can use ordinary plugs, but you have to be careful to position the plug so that any expanding jaws open across the board’s width and not across the thickness where they could cause the board to break up.

The initial stages of the job are exactly the same as for the overlap joint -marking out. Drilling the clearance holes. And so on. The difference is that instead of boring pilot holes in the second piece of wood, you drill holes large enough to take the chipboard plugs. Pop the plugs into the holes, glue the joint together and drive home the screws.

Incidentally, if you can’t use any sort of plug at all – for example, when screwing into the face of the chipboard -the only way to get the screw to hold properly is to dip it in a little woodworking adhesive before you drive it home.

The joints described so far are fairly robust, but if a lot of strength is needed it’s worth reinforcing the joint with some sort of block. The simplest is a square piece of timber.

First drill and countersink clearance holes through the block and glue and screw it to one of the pieces you want to join so that it’s flush with the end. To complete the joint, glue the second piece in position, and drive screws through into that. You can arrange for the block to end up inside the angle or outside it. Choose whichever looks best and is easiest to achieve.

With the block inside the angle, you’ll have a neat joint and the screw heads won’t be openly on display. However, in most cases it means screwing through a thick piece of wood (the block) into a thin piece (one of the bits you want to join), so it’s not as strong as it might be. If greater strength is needed work the other way round, driving the screws through the pieces to be joined, into the block. You can neaten the result to a certain extent by using a triangular rather than a square block.

Made from plastic, these are just sophisticated versions of the wooden blocks you can make yourself, and they’re used in similar situations. Their only real advantage is that they tend to give a neater result when you’re working with veneered or melamine covered chipboard, but only because they come in the right colours. There are basically two kinds to choose from.

The simplest is just a hollow triangular block’ that comes with a snap-on cover to hide the screws. More complicated versions come in two parts. You screw one half of the block to each piece of wood, and then screw the two halves together using the machine screw provided. It’s essential here that both halves of the block are positioned accurately, and since the blocks vary from brand to brand in the details of their design, you should follow the manufacturer’s instructions on this point.

If still greater strength is needed, use either an angle iron or a corner repair bracket to reinforce the joint. These are really just pieces of metal pre-drilled to take screws and shaped to do the same job as a reinforcing block (the angle irons) or to be screwed to the face of the two pieces of timber across the joint (the flat T-shaped and L-shaped corner repair brackets).

In either case, bring together the pieces of wood to be joined, position the bracket, and mark the screw holes. Drill clearance and pilot holes for all the screws, then screw the bracket to one of the pieces before glueing the joint together and screwing the bracket to the second piece. They don’t look very attractive, so use where appearance isn’t important, ie, at the back of a joint, or where the joint is going to be concealed in some other way.

There II be some situations where you cannot get at the end of the wood to use dovetail nailing. Here you must use skew nailing instead. This means glueing the two pieces securely together and then driving a nail into the upright piece of wood at an angle so it also penetrates the horizontal piece. Put a couple of nails into each side of the upright so that they cross. To stop the upright moving, clamp a block of wood behind it or wedge it against something solid.

The simplicity and splendour of wood can be seen to advantage in this sturdy occasional table made with the easiest of all joints. It’s a table to stand you in good stead indoors and out.

With this method of construction you can increase the length and width up to normal table size, though to make the table higher you might have to use thicker wood for the legs. If altering the dimensions draw your design to scale on metricated graph paper to make sure you get the proportions right – especially important where the width and height are concerned. the table was built with 18 metres (59ft) of 100mm x 25mm (4in x 1 in) softwood (in this case pine). Extra will allow you to discard pieces with unsightly knots or splits – though choosing carefully at the timber yard could help avoid this. Don’t buy wood that’s twisted or warped – caused by it being stacked at an odd angle. Reject any with signs of discoloration. The wood you buy should be planed (PAR) or dressed all round (DAR).

Accurate marking out is essential and time spent on this is worth it for the result will be a table that’s neat and firm in use. As each part is cut mark it with its name. Use medium grade glasspaper to smooth cut ends and go over all pieces with fine glasspaper after assembling.

The screws, 38mm (1 1/2in) no 8s, are countersunk and can be covered with either wood stopping or dowel plugs to give.

I

I!. a flush finish. Or you can use brass screws set in cups to make them a decorative feature. the table is made up of 4 side rails (1200mm long), 4 legs (550mm high), and 19 slats (each 500mm long) which form the ends of the table, the top, the widish shelf underneath and the narrow (1 slat wide) top shelf which is designed to stand bottles or pot plants on. If you prefer you can leave the narrow shelf out. But the spaces between the slats will have to be increased.

Begin by making up the two side frames, each from a long top and bottom rail and two legs. Connect these with two short rails at each end – dip screws in PVA adhesive to improve grip – and add slats for the bottom shelf. Use edge of spare slat as spacer. Screw another slat to underside of top rails 40mm (15/8ins) in from leg edge, to form narrow shelf, then add remaining slat to form top in same way as bottom shelf. In every case, overlap joints are used.

After assembly, the table should be sealed.

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