A frame saw or sash saw is a type of saw which consists of a relatively narrow and flexible blade held under tension within a (generally wooden) rectangular frame (also called a sash or gate). They are used for cutting wood or stone. The blade is held perpendicular to the plane of the frame, so that the material being cut passes through the center of the frame. Frame saws for use with wood are rip saws operated as a hand saw or powered in a sawmill. Frame saws used for cutting stone were powered saws in stone mills.
When used for different purposes, a frame saw may have other names. For converting logs into lumber, they are also called a pit-saw or whipsaw. For sawing veneer, they may simply be called a veneer saw. It is unknown how early framed pit-saws came into use; however, there is an Italian fresco from c. 1300 depicting their use.