Some saws have a metal frame which holds the blade in place. For the saw to cut efficiently, the frame must hold the blade taut.
Smaller saws such as coping saws will usually have solid frames. Larger ones such as bow saws, will usually have a hollow frame to keep the saw’s weight to a minimum. The frame also acts as an optional second handle, to improve control when sawing.
How is the blade held in the frame?
How the blade is mounted in the frame will vary depending on the type of saw and the manufacturer. For more information, see the various sections on how to change the blade.