Keeping your saw sharp is important. Not only will sharp teeth allow the saw to cut more easily, but it is also safer and will help prevent the saw from slipping. A tenon saw is a type of back saw often used for making cuts deep into furniture joinery. When sharpening a tenon saw, a 6 inch double taper saw file is recommended.
Make a pair of "saw chops" out of two blocks of wood. Angle the tops of the blocks so that they slope up to a point where they meet in the middle. The angle of these guideline slopes should be between 65 and 75 degrees.
Clamp the saw between the blocks of wood in a vice with the teeth facing up. Make sure the bottoms of the teeth are no more than a couple millimetres from the blocks of wood.
Use a saw set to adjust the angle of any teeth that are bent. Be sure all of the teeth are even with each other.
Check that the tops of the teeth are level with each other. Run a flat file along the top until each tooth has a new edge on it, and is level with its neighbours.
File the flat side of each tooth using the 6 inch double taper saw file at a 65 to 75 degree angle. Your saw chops should aid with the angle.
Work your way down from the handle using smooth, gentle strokes. Stop filing each tooth as soon as you see the shiny edge come through.
Turn the saw around in the vice when you reach the end and proceed to sharpen the other side in the same manner.
Brush away the metal shavings and examine each tooth carefully to determine if it has reached the desired sharpness.