A reciprocating saw is perhaps best described as a mechanised version of a hand saw. A blade is clamped into the end of the saw, and a motor drives the blade backward and forward. Typically, reciprocating saws do not have a great amount of finesse, but they are well suited to fast and crude cutting (think in terms of a somewhat safer alternative to a chainsaw rather than an electric version of a tennon saw!). As a result and they are more likely to find applications in demolition work than they are in fine cabinet making!
The following jobs recounted by users of reciprocating saws, give a good idea as to the flexibility of the tools: Cutting through tree roots below ground level. Freeing a door frame upright from the floor that it was skew-nailed to, when the nails were fully home and the frame was held firm above. Using the flexibility of a 9" blade to enable a cut to be made flush with the floor, under the jamb. Accurately cutting off a horizontal soil-pipe which was flush with the ground 500mm under the suspended floor immediately before it passed through the footings, while reaching through a 12" wide gap in floorboards. Cutting a 2m length of 50mm aris off the underside of a floor joist to make a "squint" in the ceiling above a staircase. Taking out old window frames.
There are several types of reciprocating saw. Proprietary designs like the Black and Decker Scorpion saw (not really comparable to most reciprocating saws, and more like a jigsaw on steroids), and the DeWalt Alligator Saw (a double action saw with twin counter acting blades). Most however are what one might call “standard” designs. The standard designs benefit from being able to share a large range of different blade types, and this tends to greatly add to the versatility of the tools.
Reciprocating saws are among the more benign power tools, however they are certainly not risk free! The standard design encourages the operator to keep both hands on the tool at all times. This has the added advantage of keeping him away from the sharp end! As a result of this design, most risks are of the environmental nature (i.e. you cut through something and it falls on you!) rather than from the tool itself. Like with most power tools, the use of an RCD protected power supply is recommended.
When cutting most materials, the relatively coarse sawdust produced does not represent too much of a health risk. For some cutting applications ear defenders may be required. Gloves are always recommended, as is eye protection.
One should take special care when removing the saw from the work that the blade has stopped moving completely. Otherwise, it is easy for the blade end to hit the work and cause the saw to kick back. At best, this can give the operator a bit of a jolt, and the worst could cause the blade to bend.
With prolonged use, vibration may become an issue. Note that pushing the blade stop at the nose of the saw against the material you are cutting can help reduce the vibration.
It is the wide range of available blades which give the reciprocating saw its great versatility. Metal and timber cutting blades are readily available, as are demolition blades which cut both! In addition there are special blades for cutting green wood. You can also get grit edged blades for cutting very hard materials and such as ceramics or cast iron. Blades typically range in length from 3 to 8 inches.
Since the blade is of a simple design, and there is no complex mechanism involved (unlike for example a chainsaw) so reciprocating saws can be used in quite "blade hostile" conditions like when cutting through tree roots partially covered in soil. The blade design is also very tough, and hence they can be used for cutting flush with other surfaces or even cutting slightly “round corners” rather like a pad saw.
Some people find reciprocating saws tricky to use at a first, as some practice is required to work out how to keep the blade moving and the saw steady. Using the nose of the tool to help hold it in position against the work helps greatly (much as the sole plate of a jigsaw keeps the body of the tool steady), although this is not always possible, or desirable (one of the great attractions of the reciprocating saw, being its “reach” that gives it the ability to cut in places that would be inaccessible to other power tools).
Get the blade stuck in the work, and you can end up with a stationary blade, while you try to hang on to a reciprocating saw – literally! Think through your cutting activities in advance, and arrange each cut such that the material does not “close up” on the blade as the cut progresses, thereby trapping it. Lubricating blades by rubbing with a candle or giving them a spray of PTFE lubricant can also help to prevent binding.
Better tools will exhibit better endurance and will be of a more rugged design. They will also have motors designed for continuous use. Vibration damping is also better on the higher end tools.
Variable speed is well worth having, since this allows an appropriate cutting speed be selected for material in question. A “tool free” blade change mechanism is also highly desirable (budget saws tend to require an Allen key for blade changes). A few saws also include an orbital blade action. This can help improve the speed of cut.
The cordless versions of these tools are ideal for helping you get into places the other saws cannot reach, however expect to pay a price premium for the privilege. Note also that run time will be somewhat limited as effective cutting makes quite high power demands on the tool and hence its batteries.
Nothing in particular to lookout for. Make sure that the blade clamping mechanism works correctly, check the power switch and speed controller are OK. Also check that the mains lead is undamaged.