Tenons are cuts in the end of a piece of wood to make it fit into a pocket called a mortise. Mortise and tenon joints are one of the strongest woodworking joints. They are used most often when making furniture, especially chairs and tables. A mortise and tenon joint provides a larger gluing surface for the temporary hold needed during assembly, before screws, nails or bolts are secured.
Decide how long and wide your tenon needs to be. This is based on the depth and width of the mortise into which it is supposed to fit. If the mortise is three inches deep and one inch wide, the tenon needs to be three inches long and one inch wide.
Make a mark on all four sides of the board you need to cut to make your tenon. Using the three inch deep mortise example from Step 1, the mark should be made at three inches. Connect all four marks so that you have a penciled band all the way around all four sides of your board.
Mark one end of the board from Step 3 so that the board will be cut to the dimensions of the mortise. A mortise should not be wider than half the total thickness of the board or longer than two thirds of the total width. Only a few mortises are ever deeper than three to five inches.
Place your saw blade on the mark you made in Step 3 on the edge of the board which will become your tenon. Saw down until you just barely reach the three-inch mark made in Step 4. Repeat until all four sides of the tenon have been cut to the mark.
Reposition your saw so that you will be cutting into the wood along the line you made in Step 2. Use a slow, careful stroke to cut into the end of your board, one side at a time. Repeat for all four sides of the line from Step 3. At this point, you should have a three-inch long, three-inch wide by one inch thick tenon at one end of your board.
Apply glue on all sides of your tenon. Wait for the glue to become tacky, then slide the tenon into its accompanying mortise.Allow the glue to finish drying. If you are making primitive, ranch style or log style furniture, drill bung holes into the joint. Insert dowels to make the joint even stronger. If you are making more modern furniture, use wood screws.