The mortise and tenon is an essential joint in woodworking. It enjoys numerous variations and can be completed using a variety of techniques. The application of the mortise and tenon for frame joinery extends beyond the world of woodworking into house-building, although the time-consuming practice is very seldom used in that arena anymore. The mortise and tenon joint shown here is used in the construction of a basic table.
Step 1. Mark the ends of your blanks.
Use a pencil to mark the ends of your blanks (legs) for reference. Consider using a triangle as your reference mark, as the triangle can only be correctly reassembled by correctly configuring the four pieces.
Step 2. Mark the location of the mortises.
Use a pencil to mark the rough location of the mortises on each of the blanks. Use these marks as references to ensure that the mortise is cut into the proper side of the blank.
Step 3. Set the combination square and mark for the mortise.
The actual location of the mortise will depend on your decisions regarding the tenon. In this case, the rails (which will have the tenons) are 3/4 of an inch. For the tenon, 5/16 of an inch will be taken off. So set the combination square for 5/16 of an inch and make a mark on the blank.
Step 4. Mark for the width of the rail.
Set the combination square for the width of your rail. Using the combination square, mark down from the top of your blank for the width of rail. Use a pencil or a knife to make the mark.
Step 5. Mark for the haunch of the tenon.
This particular mortise and tenon will include a haunch on the tenon that measure an inch. Set the combination square for an inch and mark down from the top of the blank.
Step 6. Mark the line for the mortise.
Set the marking gauge for 5/16 of an inch and scribe a line between the haunch reference mark and the rail width reference mark.
Step 7. Use a pencil to indicate the material to be removed.
Use a pencil and mark the material to be removed to form the mortise. In this image, notice that the back line of the mortise has been drawn in as well. This is helpful but not necessary. The location of the front line is most important.
With the location of the mortise set, it’s time to use a mortise machine or a drill and chisel to remove the mortise material.
