Reciprocating saws are powerful handheld tools equipped with a strong, wide blade that cuts in a back-and-forth motion much like a jigsaw. However, the width of the blade typically prevents the reciprocating saw from making tight, curved cuts like a band saw. Reciprocating saws are commonly found on construction and remodeling job sites, as they are particularly adept at cutting through a variety of materials (wood, metal, drywall, plastic, PVC to name a few). They are quite useful for cutting out holes for windows and doors in an existing wall.
The first reciprocating saws were built in the early 1950's by Milwaukee Tools, carrying the name of Sawzall. The name obviously stuck with the tool, as Milwaukee's Sawzall has been a name that has been synonymous with the reciprocating saw among builders for many years.
Reciprocating saws are basically simple power tools: a corded (or cordless) motor is attached to a drive mechanism that creates a piston-like motion through the front of the tool. A chuck on the tip of this mechanism allows for interchangeable blades to be attached to the tip. When the user depresses the trigger on the handle, the motor and drive mechanism power the chuck and blade back and forth as many as 3000 strokes per minute (even higher on some models). With plenty of power at his disposal, an operator cutting a hole for a window in an existing wall, for instance, can thus push the blade through wood, drywall, nails, pipes, old wiring or nearly any other material (short of masonry) that they might encounter in the wall.
Modern reciprocating saws have quite a few features that were not found on some of the original Sawzalls back in the 1950's. For instance, modern reciprocating saws are almost all equipped with variable speed motors. The speed at which the blade reciprocates back and forth is controlled by how far the trigger is depressed.
Simply put, squeeze the trigger a bit harder for more speed. This easily adjustable speed mechanism allows the operator a great deal of control, particularly helpful when attempting to make some wide curved cuts (such as moving from the side of a window cut-out to the sill on the bottom of the window cut-out).
Another widely adopted feature on today's reciprocating saws is an oscillating blade action. This oscillating motion means that for every back stroke, the blade angles downward into the cut slightly, and for every push, or forward stroke, the blade angles upward slightly. This causes an oscillation motion that helps cut through materials, particularly wood, much faster. It tends to cause a rougher cut than a straight back-and-forth cutting motion, but reciprocating saws typically aren't considered precision cutting tools, so the finish of the cut is rarely an issue.
One feature that has been adapted in just the past few years is a chuck that allows for tool-less blade changes. By twisting the chuck with one hand, the blade can be slid out of the chuck with the other hand, and a new blade inserted quickly and easily. Most tool-less chucks can even allow for the blade to be inserted upside-down (with the teeth facing upwards) for added cutting versatility.
Reciprocating Saw Blades:
Manufacturers of reciprocating saws typically make blades for cutting through a number of different materials. The two most common blades are wood blades (typically with six to ten aggressive teeth per inch (TPI) of the length of the blade) and combination blades (commonly called bi-metal blades) that have up to 20 teeth per inch, and are more versatile, as they can be used for cutting wood, metal, plastic, PVC and more. Some manufacturers have blades specifically for metal as well.
Reciprocating saw blades typically are sold in two different lengths, a short blade (about six inches long) and a longer version (about 12-inches of exposed teeth). While the longer blades can obviously cut much deeper, they are harder to handle, can whip side to side quite easily, and are also very prone to bending, particularly when the tip is forced directly into another object.
Reciprocating Saw Safety:
On the tip of the reciprocating saw, there is a shoe through which the blade extends. When cutting with the reciprocating saw, be sure that the shoe is held firmly against the workpiece. This will help with vibration and considerably reduce the chance of the saw kicking back, particularly when working with long blades.
Speaking of long blades, keep in mind that at high speeds, longer (and thinner) blades will have a tendency to whip side-to-side. When you encounter this whipping action, ease off on the trigger to slow down the speed of the motor, which will help to bring the blade back under control. This is especially problematic when blades are a bit used, as the considerable heat (generated by friction between the fast back-and-forth motion of the blade and the edges of the workpiece being cut) can weaken the steel in the blade, making it more susceptible to whipping.
Of course, since this friction generates quite a bit of heat, the blade will be difficult to handle when removing it from the chuck. The best way to handle a hot blade is to simply hold the saw vertically, loosen the tool-less chuck and let the blade fall onto a safe surface below where it can cool safely before being picked up.