Even though wood is often bought ready planed, or machined, in one form or another it is frequently necessary to prepare the timber to non-standard sizes in the workshop. If the timber is received ‘sawn’ then it must be prepared before it can be used.
Preparation includes reducing all the wood needed to required sizes by sawing and planing. For as long as can be established the planing and preparation of wood by hand has followed the same basic principles, with the same basic terminology and guide marks.
First the ‘face side’ is established. The better side of the timber is selected. It is then planed smooth and flat, tested with a straight-edge lengthways, crossways and cornerways until it is right. The ‘face edge’ is next prepared, planed and tested with straight-edge and try-square, held tight against the face side; finally it is marked with the face edge mark.
Your timber is now gauged and planed to the required width. Gauge from the face edge, across the face side and underside to the required width, holding the gauge stock firmly to the face edge. Plane off the waste, testing frequently as before.
Now the timber is gauged to the required thickness on both edges, and ends, holding the gauge on the face side. Waste is then planed off, testing as before.
Usually the next step after planing is to mark out the length, although whether or not the waste at the ends is removed at this stage depends on the nature of the job.
When planing along the grain always plane with it, not against, otherwise tearing and digging-in may occur. The run of the grain is easy to see on the edge of the section. If the wood is planed on the end grain in a similar manner to how it is planed on the edges then it is almost certain to split at the far edge. If the wood can be supported at the corner, so that the edge cannot be forced outwards, then splitting will not occur.
When wood is planed on end grain it is usually referred to as ‘shooting’. The following methods are ways of doing this which will prevent splitting. 1. Planing in both directions but not allowing the plane to complete the stroke and reach the far corner. 2. Removing the corner. This can only be done if the removal of the corner is of no consequence, perhaps because of subsequent shaping. 3. Cramping scrap wood on workpiece. The scrap wood, in effect, extends the width of the wood and any splitting will therefore be in the scrap piece. If the scrap is chamfered then even this is not likely to split. 4. Using a shooting board. This is a very satisfactory method providing the wood is not too large. If the shooting board is accurate the wood is not only planed, but it is finished square and true.
As end grain offers greater resistance to the plane it is essential for all end grain cutting that the plane is kept very sharp.
Cutting a trench
Making a trench is a fairly simple operation and forms the basis of a number of joints: housing, bridle and half-laps of various kinds. When using a saw to cut joints the cut must be on the waste side of the line.
Dimensions represent the finished size of parts of the joints being made.
The width of the trench is made exactly equal to the width or thickness of the part fitting into it, and is best if initially squared in with a pencil. That part of the joint which is actually going to be cut can be gone over with a marking knife. A marking knife lightly cuts the surface and gives a more accurate mark to work from, and working this way also gives an opportunity to check the precise width needed. A gauge is used to mark the depth. Remember to have the stock against the face side when gauging. First mark off the trench, squared across, in pencil. Mark the depth of the trench with a gauge. Go over the lines, where actual cutting is to take place, with a marking knife then chisel in small V-grooves on waste side of lines. Saw down to the gauge mark, using V-grooves as guides for the saw, which must cut on the waste side of the line.
Chisel away waste at one side. Use as large a chisel as possible. Keep the flat side of the chisel down to the work and cut by pointing upwards on one side. Repeat this stage, working from the opposite edge. Level off the remainder of the waste by working inwards from the edges.
This is the type of trench used for half-lap joints and is half the thickness of the member. Trenches for other purposes are usually made one third of the thickness.
A stopped trench is often used for bookcase shelves and similar work. It is marked out as described for a through trench, using a gauge to mark the limit of the ‘stop’. Marking knife and chisel are used to make V-grooves, then a mortise is cut with the chisel at the ‘blind’ end of the trench. This allows sawing along the V-grooves to be carried out. Ideally a router should be used to level off the bottom of the trench but this tool has not yet been described and careful use of a sharp bevel-edge chisel should produce a satisfactory ‘bottom’. The completed trench is shown at.
Perhaps the most traditional joint of all, employed by stonemasons and blacksmiths as well as woodworkers, is the mortise and tenon. It is probably more widely used than any other joint in woodwork, and has variations of one sort or another that are almost countless. Its basic forms, though, are quite simple.
For very simple work tenon edge shoulders are not usually included. For furniture projects, edge shoulders are often incorporated as they completely seal, and conceal, ends of the mortise. With wide pieces the tenon is normally made in the form of a double tenon.
The shoulder of a tenon is marked with a marking knife and the location of the mortise is made in pencil. Thickness of the actual joint is gauged with a mortise gauge. Corresponding parts of the same joint should be marked at the same time, while the gauge is ‘set’.
Ideally, a mortise gauge should have the distance between the pins set directly from the chisel which will be used for cutting the mortise. This is because chisels vary slightly in size and their widths are frequently not exactly what they are specified to be.
A blind or stopped mortise and tenon is shown at. Small, usually about 3 mm, shoulders are also introduced to conceal ends of the mortise.
Where the wood being joined is of unequal size, thickness of tenon can be increased above the usual one third rule, as in.
An open mortise, also known as a corner bridle, is shown in. This is a simple joint often used in framing.
More involved, and stronger, the haunched mortise and tenon is also used in frame construction. In practice it is usual to allow a little extra on the length of the mortised member to add strength during handling. This ‘horn’ or ‘joggle’ is cut off after assembly or when the frame is positioned.
A long mortise, in relation to the thickness of the part, would weaken the joint. In addition to gluing, the joint can be further secured by wedges which should have a slope of about 1 : 7. Ends of mortises are cut on a complementary slope to provide ‘wedge’ room. Screws or dowels can also be inserted. »-/v yj ~
Mortises can be formed either entirely by chisel or the bulk of the waste can be removed by a chisel after the centre has been bored out with brace and bit. The bit must be smaller in diameter than the width of the mortise and the holes must not touch the sides of the mortise.
A series of vertical and sloping cuts are made, just inside the lines, about halfway through the wood and. Extra sloping cuts are made in the centre part to level off the bottom. The work is then reversed and the first three steps are repeated. The chisel is now placed exactly on the line; the remaining waste is trimmed away, as in. Check that the ends of the mortise are not rounded as this would give a false sense of tightness, when in fact the tightness is located at the centre. Remember that all surfaces in contact should have parallel sides.
Tenons are normally cut by sawing, with the saw just touching the line on the waste side. It is better to make the cuts with the grain first, followed by sawing the shoulders as, otherwise, some of the marking out may be lost if the side of the tenon is completely removed before all the cuts down the grain have been made. It is better to rasp away any excess rather than cut it away with a chisel.
When sawing a tenon, work is held upright in the vice. The handle of the saw is lowered as sawing continues without the front of the saw cutting any deeper. Now slope the wood slightly in the vice and continue sawing by lowering the handle until the shoulder line is reached. Reverse the wood in the vice, but keep it vertical, and continue sawing, keeping the saw level, until the shoulder line is reached. The sequence of cutting on a tenon with edge shoulders is shown in.
It is the joint usually adopted where a piece has to be jointed to a component which is thinner. Care should be taken to see that the joint is not made too tight, or the forked parts will tend to be forced outwards, which can even result in splitting.
The dovetail joint, when correctly made, is a very strong joint as, by the nature of the slope it resists attempts to pull it apart except in the way it was assembled. This is the most simple variation of the joint, the basis of which is the sloping part of the joint which resembles the tail of a dove. Because of the slope this joint can only be assembled in one direction and will resist being pulled apart in any other.
Dovetailing is easiest if carried out from a squared off end, as the extent or limit of the joint can then be readily marked with a cutting gauge. By standing the piece with the pins on the opposite member and marking around them with a well pointed pencil the exact size, shape, slope and position of the corresponding tails or ‘sockets’ can be accurately marked out. This means that for something like a simple box or frame the marking out must be done so that all four pieces will properly fit together. Face side and edge marks on all work and individual labelling of each half of each joint, will help to prevent errors.
Pins are indicated and is the tail. It is usual to cut the pins first. The tail is then marked directly from the pins, as shown, after having squared or gauged in the guide line. Corresponding parts of dovetail joints are usually individually ‘tailored’ in this fashion.
Common or box dovetails follow the same basic pattern as do the single dovetails. It is more satisfactory and gives a better joint if a pin is arranged to come at the edge, and not a tail.
First shade in the waste to avoid errors in sawing. Next, saw down the grain on the waste side of the line. Cut out the bulk of the waste with a coping saw, keeping just clear of the line going across the grain. This line is usually made with a cutting gauge. Chisel away the remainder of the waste, checking that surfaces are flat and square.
The angle at which a dovetail is cut must be considered: if it is too slight the joint will tend to slide out, and if it is too great there is a danger that the corners of the tail will break away. By long usage and practice it has been established that the angle should be about one in seven. If the wood is hard and close grained a slightly smaller angle can be employed, but the limit at all times is considered to be one in eight.