Coping saw

From Wikipedia, the free encyclopedia
Jump to: navigation, search
A coping saw.

A coping saw is a type of hand saw used to cut intricate external shapes and interior cutouts in woodworking or carpentry. It is widely used to cut moldings to create coped rather than miter joints. It is occasionally used to create fretwork though it is not able to match a fretsaw in intricacy of cut, particularly in thin materials. Coping saw blades are always thicker and much coarser cutting than typical fretsaw blades and many others of its family members.

A coping saw consists of a thin, hardened steel blade, stretched between the ends of a square, c-shaped, springy-iron frame to which a handle is attached. The blade is easily removed from the frame so that the blade can be passed through a drilled hole in the middle of a piece of wood. The frame is then re-attached to the blade and the cut starts from the middle of the piece. Long cuts perpendicular to the edge of the material are possible but the shallow depth of the frame rather limits how far from the edge one may cut. The much deeper frame of the fretsaw is more useful for cutting well away from the edge but conversely cannot manage the thicker materials commonly cut by the coping saws.

The coping saw blade is removable by partially unscrewing the handle. The blade is prevented from rotating by means of the short, steady bar provided where the blade is attached. Loosening the handle also allows the blade to be rotated relative to the frame as desired. Carefully aligning the finger steady bars at the top and bottom of the blade ensures that the thin blade is straight and not twisted along its length. Retightening the handle tensions the blade and locks it at the desired angle relative to the frame. The short steady bar nearest the handle is held securely between finger and thumb while the handle is tightened to ensure the blade remains at the desired angle. Unlike the fretsaw the coping saw blade has holding pins which lock securely into the angled slots of the rotatable blade holders.

The direction of the cut is quite easy to change because of the thinness of the blade. Gentle curves are achieved by slowly turning the whole frame by means of the handle while continuing to cut steadily. When necessary, the blade can also be rotated with respect to the frame to make sharper curves in the material being cut. The teeth on a coping saw blade should normally face the handle (i.e., "backwards" as compared with most other Western saws); the action of pulling the coping saw allows the frame to remain in tension (and thus reduces blade breakages). This is the opposite to most other saws which only cut in the "push" direction. Normally the coping saw is used in the vertical position and reciprocated by hand power for the maximum stroke possible without striking the material with the frame. This takes much practice. It may also be used in all other attitudes when the work requires it but even greater skill is required. Blade breakage is much rarer than with a fretsaw.

A coping saw (with the correct blade) can also be used to cut through aluminium tubing and other metal objects, though a hacksaw is much more efficient for this task. The thin blade tends to make wavy cuts in thick materials unless skill is achieved through much practice on a wide variety of materials of varying thicknesses. The stroke length before the frame strikes the material above or below is the limiting factor in the maximum thickness of material. The work becomes progressively more difficult and tiring with increasing thickness of material.

A coping saw is often used with a V-board, also known as a birdsmouth board, which is a flat board with a "V" shaped cutout in one end. In use, the V-board is clamped to the bench so that the section with the cutout hangs over the edge. This allows the work to be held down flat whilst shapes are cut into it. Either the work or the saw frame may be rotated. The V-cutout allows the coping saw blade to pass through the work unimpeded. This technique is common in marquetry. Pressed, chrome-plated, steel V-boards are also quite common though care must be taken to avoid damaging the blade teeth by excessive rubbing on this hard material.

See also[edit]