Body position and technique matter. Position the chisel with two hands. Then tap firmly with the mallet to set the edge of the chisel.
Layered Method
Cut 5 lets you begin scooping out the waste
Full-Depth Method
Begin near the middle and chop first one way, then turn the chisel and chop the other way.	Get to full depth with several chops, then remove waste with a top-to-bottom chop.
Step by step: cutting the tenon
For Cut 1, start at the far edge and cut the end-grain kerf.	For Cut 2, saw down the line nearest you, right down to the shoulder line. Be sure to keep the saw edge in the end kerf.
For Cut 3, reverse the workpiece and saw to the shoulder line.	In Cut 4, clamp the workpiece upright and saw down to both shoulder lines.
After Cut 4, make the vertical cuts for the tenon's two edges.	The structural shoulders are removed while holding the workpiece in a bench hook.
Flip the piece over while still in the bench hook and saw the edge shoulders.	Use the wide bevel-edge chisel to fine-tune shoulders.

Once the joint has been designed and marked out, there are two basic processes involved in making a mortise-and-tenon joint by hand: chopping out the mortise and sawing the tenon.

Certain tools will make the job easier and yield better results. For the mortising, you'll need a mortise chisel, a try square and a joiner's mallet. The mortise chisel differs from regular wood chisels in that it is made to withstand blows from the joiner's mallet and to lever out material without breaking. The joiner's mallet is recommended rather than a carver's mallet or deadblow hammer because the carver's mallet isn't designed to deliver the heavy blows required to chop out mortises, and the dead-blow hammer reduces one's ability to feel when the chisel has been driven as far as it can go. To help guide your progress, place a piece of blue masking tape on the back of the chisel at the mortise's correct depth. Stop chiseling when you reach that point.

There are two methods for chopping out the mortise: the layered method and the full-depth method. The layered method involves repetition of a five-cut process to remove material:

Cut 1: Stand behind the work and position the chisel, flat side away from you, about 3/16" from the far end of the mortise. Tap lightly to set the chisel, then hit it hard. To remove the chisel, lever the handle away from you.

Cut 2: Position the chisel about 3/16" closer to you. Tap lightly to set it, then hit hard again. The second cut went deeper because of the space created by the first.

Cut 3: Position the chisel another 3/16" toward you for Cut 3, which will go deeper still.

Cut 4: Position the chisel back in Cut 1 and hit it hard to drive it to the same depth as Cut 3.

Cut 5: Finally, position the chisel, back face away from you, another 3/16" behind Cut 4. Drive the chisel, then work the handle toward you to remove the waste.

Typically, the first round of cuts clears the mortise to half its final depth and the second round clears it to its final depth. The full-depth method involves a succession of cuts beginning in the center of the mortise and moving outward as the full depth is reached.

Whatever method is used, one of the last steps is to square the end walls of the mortise by holding the back of the chisel against them and checking with a try square.

With the mortise done, it's time to turn to the tenon. As with chopping the mortise, the right tools are key: a tenon saw (and not a dovetail saw, the blade of which is too thin and will wander) and a wide bevel-edge chisel. Cutting the tenons involves four initial cuts to define the tenon and several subsequent shoulder cuts to remove the waste (see photos at right). The bevel-edge chisel is used to clean up the shoulders to ensure a tight fit.

The pieces should come together with a tight push fit. If it's loose, try again. If it's tight, pare the tenon across the grain until it fits.