Mortise and Tenon Jig

How to Cut Mortise and Tenon?

How to Make a Mortise and Tenon Joint

Mortise and tenon joints are the preferred joint style for furniture and cabinetry. It is strong, durable, and little affected by the expansion or contraction of wooden elements due to changes in temperature and humidity. When properly formed, mortises and tenons can even be decorative elements in the finished look of a room. Making a tenon-and-mortise joint can be a tall order for the novice woodworker, but with the right tools, shaping the parts is a fairly straightforward process.

Arrangement of the joint

As any seasoned cabinet maker will tell you, the proper layout is just as important as the cut and shape to follow. A perfectly formed post that is the wrong size or shape is not at all successful. The tenon should be between one third and one half the thickness of the stock from which it is made. Set your mortise gauge to the chosen tenon thickness, positioning the points so that it marks a pair of lines that stand apart. Then place the block on the gauge so that the lines are drawn equidistant from the sides of the stock. Also, mark the shoulder lines where the stock is to be cut above and below the tongue.

Cut the Tenon

Your rear saw can do the job. A router can also be used, as can a dado head on a table or a radial arm saw. In each case, adjust the height of the blade separately for shoulder and face cuts. On the table saw, position the fence so that the distance between the opposite side of the blade and the fence matches the desired length of the tenon.

Cut the mortise

The depth of the mortise should be approximately three times the thickness of the tenon. It can be cut in many ways, one of which is the traditional approach of using heavy-duty mortising chisels and a mallet to chisel the hole by hand. Another option is to use a Forstner bit or auger on your drill or drill stand to start the mortise, then clean and square it with a chisel. You can also use a router; a router is particularly useful for mortising. A much simpler method is to use a mortising attachment on your drill press. The device consists of a yoke that clamps the attachment just above the chuck on the nib (the main stationary shaft of the drill press, in which the spindle turns). At the bottom, the yoke is equipped with a hollow chisel with square corners. Different sizes of scissors are sold, with matching tips. When using the mortising attachment, the drill press works the same as when performing ordinary drilling tasks. The rotating bit will do most of the cut, but the chisel pulls away from the corners around the hole, producing the mortise hole. While cutting mortises, the sides of the chisel must be square to the stock. Do not force the bit, allow it to establish a cutting speed that does not cause the bit to jam in the wood.

Seal fixing

Glue is often used to join mortise and tenon. A combination of the two is the strongest. Before applying glue, secure the joint together. Allow it to dry to make sure the fit is perfect. Drill holes for pins or dowels, dismantle, and then apply glue. Tighten the pieces together and insert the studs, letting them protrude from both sides of the joint. Scrape off any excess glue visible from the surface of the wood. Once the glue has set, remove the clamps and cut the studs using a sharp chisel or flush saw.

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