Uses for a Coping Saw
Trim carpenters primarily use coping saws to shape the ends of molding -- particularly crown and baseboard molding -- to produce tight-fitting corner joints, in a process called coping. In the woodworker's shop, a coping saw is an indispensable tool for many marquetry and inlay projects and for cutting decorative shapes. Hobbyists reach for the coping saw when they need to cut shapes for wooden models. When equipped with the proper blade, a coping saw also can cut shapes in tile and metal.
Mounting the Blade
With a typical width of 1/8 to 1/4 inch and a thickness in the neighborhood of 0.02 inches, a coping saw blade essentially is a piece of wire suspended between the supporting pins on either end of the saw frame. It can cut on the push stroke or the pull stroke, depending on how you orient the blade: Install it with the teeth facing toward the handle for cutting on the pull stroke; face the teeth away from the handle to cut on the push stroke. You must tightly tension the blade by adjusting the pins or turning the handle -- but be careful; there's a limit to how much tension you can apply without breaking the blade or rendering it vulnerable to breakage the first time you use it.
Using the Saw
Before cutting a shape, it's important to draw an accurate line with a sharp pencil -- or even a knife -- to give yourself a reliable reference; the blade easily can wander over a coarse line and produce an inaccurate cut. Hold the saw perpendicular to the wood and use gentle pressure while sawing at a moderate speed. The saw tends to chip wood at the beginning of a cut. To prevent this, make an indentation with a file before sawing. You can cut shapes in the middle of a board by drilling a hole, removing the blade and passing it through the hole, then connecting it to the saw.
The coping saw derives its name from the procedure trim carpenters use to join profiled pieces of molding, such as baseboard or crown molding. The procedure for coping a 90-degree angle starts with installing one piece of molding with a butt (square-cut) end flush to the wall. After cutting an inside 45-degree bevel on the joining piece, the carpenter cuts the end of the joining piece with a coping saw, following the profile of the molding. The coped end of this piece is then butted against the face of the installed molding to complete the coped joint. When coping trim It's important to support the molding securely on a table -- clamping it if necessary -- to prevent movement or vibration while sawing.