Why are mortise and tenon joints good

A mortise is a cavity cut into a timber piece in order to receive a tenon. Below are the various types of mortises and tenons performed in woodworking:. Stub mortise : it is a shallow mortise; its depth is determined by the size of the timber and the mortise does not go through the workpiece. Wedged half-dovetail : in this mortise, the back is wider, or taller than the front.

The space for the wedge initially creates space for the insertion of the tenon. The wedge prevents the withdrawal of the tenon after being engaged. Through-wedged half-dovetail : in this mortise type, it passes entirely through the piece. Read: Everything you need to know about lap joints.

Tenon is a projection on the end of a timber piece which design to fit in a mortise when inserted. It is usually wide but taller than the wideness. Below are the various types of tenon cut by woodworker:. Stub tenon : the depth is depending on the size of the timber piece and the tenon is shorter than the width of the mortise piece so it does not show.

The smaller end of the wood is the "tenon," and the wood with the hole in it is referred to as the "mortise. Like the dovetail joint, a mortise and tenon can be carved by hand, but that requires a certain skill level and aptitude for using a wide variety of hand tools. The easier and less time consuming way of cutting mortise and tenon joints is by using power tools. It's best to cut the mortise first and the tenon second. You'll find it much easier to fine-tune and adjust a tenon to fit into a mortise, then the other way around.

A rule of thumb for cutting tenons is that they should be equal half the thickness of the board, and tenon length should be 4 to 5 times the thickness of the tenon.

A router with an upspiral bit is the preferred power tool for cutting a mortise, and an edge guide attached to the router base ensures a straight cut. A woodworking work bench with a vise makes this process much easier. It offers a fair amount of gluing surface but the open ended, continuous groove has weak sides that can crack fairly easily if stressed.

This weakness can be overcome by gluing a plywood panel into the grooves. When a deeper, fully enclosed mortise is cut to accept a longer tenon, you end up with a much stronger joint drawing above. Since the sides of the mortise are supported by the wood on either end, the chance of splitting is much less likely. Greater gluing surface is another benefit. This is a good choice for joints that will be put under stress, such as a rail-to-leg or stretcher-toleg joint of a chair or table.

The tenon can be made with shoulders cut on all four edges, as shown, or just the two long edges. A two-shouldered tenon has the advantage of being easier and quicker to make.

A four-shouldered tenon has greater racking resistance and ensures that any gaps between the ends of the mortise and the tenon will be hidden. When a tenon is cut back or notched along one edge, the resulting short stub is referred to as a haunch drawing above. This type of mortise and tenon joint is commonly used in making heavy-duty frame and panel assemblies. The obvious benefit here is that the haunch fills the end of the groove. A haunched tenon can also offer structural benefits.

For example, when making a large table frame, a haunched tenon offers a slightly stronger choice for joining the rails to the legs.

The mortise can be reduced in length and kept back from the end of the leg, reducing the likelihood of splitting. A shallow groove between the mortise and the end of the leg holds the haunch on the tenon.

This arrangement creates a continuous gluing surface and also provides a mechanical connection that keeps the rail from twisting out of alignment. For heavy-duty, structural applications, a through mortise and tenon, as shown in the left drawing below, is often your best option. This traditional variation is designed to maximize the mechanical strength of the joint.

A trestle base for a workbench or table, or a large door can benefit from the added rigidity a through tenon provides.