From DIYinfo.org
Angle or cross joints are used for joining timbers not in the same straight line; examples of these are Lapped Joints, Housing Joints, Mortise and tenon, and Dovetailed.
[edit] Half Lap Or Halving Joints
The halving, or half lap joint is one of the most versatile woodworking joints used in carpentry and can be used in all kinds of framework from delicate side tables to a full framed timber building. So, for building hardwood and softwood frames or repairing damaged timber around the house, a practical knowledge of halving joints is a real asset.
Halving joints are so-called because both members of the joint are halved in thickness so that the faces of the finished assembly are flush with one another. There are three basic types of halving joint: the tee halving, the cross halving and the corner halving.
The cross halving is used where two members have to cross each other without increasing the thickness of the frame, such as in the diagonal stays of tables and chairs (fig. A).
The corner halving is used where the members meet at their ends, for example the corners of a rectangular frame (fig. B).
The tee joint is often used in cabinet framework where the end of a rail meets another piece some distance from the end (fig. C).
To produce a neat finish, the joint can be stopped, cut short of the cross piece of the 'T', so that the outside edge does not show the end grain (fig. D).
But a stronger joint is made if one of the edges is sloped to provide a shoulder, so that the two members can be separated in one direction only (fig. E).
Alternatively, both edges can be sloped to produce a dovetail halving joint (fig. F). This type of joint is often used as an intermediate rail on a long table to prevent the sides from bowing.
A mitred corner halving is often employed when the surface has to be moulded (fig. G).
The interlocking parts of a halving joint are known as 'pins' and 'sockets'. The tee halving joint consists of a pin cut in the cross rail and a socket in the side rail into which the pin is fitted.
Corner halving joints consist of a pin in each member, and cross halving joints of two sockets.
[edit] Housing Joints
A Housing joint is similar to the Halving joint where the thickness of one member is cut half way into other member (normally at 90 degrees). Because of the simplicity of the joint it is very commonly used in carpentry both externally and internally.
The Through Housing joint is most commonly found in internal joinery, such as shelves, partitions, divisions, stairs and cabinet framework, where the edge appearance is not critical, as no matter how well the joint is made it is visible to the eye. (fig. A).
For better improved edge appearance the Stopped Housing joint is normally the best to use. (fig. B)
[edit] Mortise and Tenon Joint
Mortise and tenon joints are used in a wide variety of work, ranging from coarse carpentry through joinery to the finest cabinet work. Their most common applications are in roofing, window frames and door frames, stud partitions, tables and chairs.
The component parts of the joint are known as the stile, the vertical member which usually holds the mortise (a rectangular hole the same size as the tenon is cut into the side or face).
The rail, the horizontal member usually with a tenon (a rectangular tongue is cut to half the thickness of that timber and the length of the thickness/width of the stile) at each end.
In the simplest mortise and tenon joint, used only in the roughest carpentry work, the rail fits straight in to a mortise in the stile (fig. B). More usually, though, the rail is trimmed to leave 2-6 mm shoulders on either face (fig. A). These effectively hide any gaps—such as those caused by a slack-fitting tenon or by careless cutting-out of the waste in the mortise.
This type of mortise and tenon joint is called a plain joint. It can also be classified according to the way in which the mortise and tenon meet.
1)Through
2) Stub or 'Blind'
3) Through Wedged
4) Foxed Wedged.
An additional complication, haunching is sometimes introduced to stop the rail from twisting, and to take strain off the tenon (fig. A). And on large rails, the gluing area can be increased by employing a double tenon with haunching (fig. G) the strongest mortise and tenon joint.
Some of the above permutations are occasionally combined, making the whole business of mortise and tenon joints look far more complicated than it really is. For example, on high quality door frames you may find that some of the joints are of the foxed wedged double tenon type.
In fact, the only joints which are really difficult to make are those where the stile and rail are moulded requiring you to scribe and cut complicated shapes.
A. A conventional haunched through joint of the type found on many older window and door frames.
B. A simple stub joint in which the tenon has no shoulders. This is used only for the simplest frameworks
C. In the plain through joint, the tenon passes right through the stile and is trimmed off after assembly
D. For a stub joint, the mortise in the stile must be cut to exceed the length of the tenon by 3-5 mm
E. For a through wedged joint, wedge room must be cut on either side of the mortise. The wedges are driven in after the joint has been assembled
F. The foxed wedged joint, which incorporates secret wedges, is little used today thanks to the strength of modern woodworking adhesives
G. A double haunched joint has exceptional strength. The waste between the tenons is cut with a coping saw taking care not to weaken the tenons
[edit] Dovetail Joints
The ease of use and strength of modern adhesives means that nowadays there is less need for complicated joints like the dovetail. But although the dovetail is one of the most difficult joints to manufacture, it is definitely the best joint to use in the construction of traditional furniture which is expected to stand up to hundreds of years of wear. In such cases the use of adhesives can lead to the joint breaking as a result of vibration. Furthermore, the dovetail is one of the most attractive joints for something like a linen chest.
Dovetails can be made both by hand and machine. Simple proprietary jigs for the do-it-yourselfer are available, but best of all are the special hand held power routers that will produce a perfect dovetail within a few seconds.
Types of Dovetails
There are four distinct types of dovetail used in carpentry, cabinet and joinery work:
1. The through dovetail which shows both sides of the corner joint; (fig. A)
2. The lapped dovetail which shows on one side but is concealed on the other, as in drawer fronts; (fig. B)
3. The double lapped dovetail in which only a thin line of end grain is visible; (fig. C)
4. The secret mitre dovetail where the joint is entirely hidden.
The component parts of the joint are known as the dovetail—the female part, and the pin—the male part. Usually the pin, at its widest, is about half the width of the dovetail. However, the tails can be up to five times the width of the pin. For very strong work the pin and dovetail may be of equal width; this is called a cistern dovetail, and is nearly always the rule in machined joints. The slope, rake or bevel of the dovetail is the angle that gives the joint its strength. The slope is measured as a proportion of the width over rise,
1 in 5, 1 in 6, 1 in 7, or even 1 in 8: 1 in 5 is usual for work where strength is more important than appearance, and 1 in 7 or 8 where the reverse applies. It is essential for the integrity of the joint not to exceed these extremes. One important difference between cutting dovetails and other joints is that of wastage. In the manufacture of all other joints it is normal to mark out the timber and joints, leaving an additional 6 mm of waste, which is removed after assembly. In the case of dovetail joints, however, it is rare to leave on any waste; and even when it is, as in through dovetails and the male side of lapped dovetails, the maximum amount left should be 1 mm any more than that will lead to inaccuracies.
When you prepare materials for dovetails you must mark and cut them to the exact length, including any waste, and the ends must be shot square with a plane. Two adjoining sides need not be of the same thickness as you can adjust the length of the tails. The exception to this is the secret mitre dovetail in which the adjacent sides must be of equal and even thickness to allow the mitres to meet.
