A jigsaw is a handheld power saw designed for cutting curves, openings, and irregular shapes in wood, plastic, and thin metal. Its narrow blade moves up and down rapidly, allowing the user to steer along a drawn path instead of cutting only straight lines. Jigsaws matter in workshops because they combine flexibility, portability, and relatively safe control compared with larger stationary saws.
They are often the first choice for making curved cuts, sink cutouts, and shaped project parts.
Understanding Tools & Workshop Machines: Jigsaw
The blade is held at one end, so it can turn through tight curves that would trap a wider saw blade. This useful flexibility has a limit. A blade can bend sideways if the user pushes too hard or turns too sharply.
The result is a cut that looks correct on the top surface but leans underneath. This is called blade deflection. For accurate work, keep the saw shoe flat against the material and guide the tool steadily.
Let the teeth remove small pieces of material at their own rate. Forcing the saw usually creates heat, wandering cuts, and broken blades.
Blade choice changes the result more than many beginners expect. Coarse teeth clear sawdust quickly in soft wood, which helps on long rough cuts. Fine teeth make smaller chips and reduce splintering, especially in plywood, laminate, or thin metal.
Metal cutting needs a suitable blade, a slower setting, and sometimes cutting fluid to reduce friction. The material must be supported close to the cut line.
If a sheet vibrates, the blade can catch and the edge becomes ragged. A sacrificial board underneath thin plywood gives support to the bottom face and can reduce tear-out.
A jigsaw cuts on the upward stroke for many common blades. This means splinters often appear on the upper face of a wooden board. Students can place the better-looking face downward when using a standard blade, if the project allows it.
Another option is a reverse-tooth blade that cuts more cleanly on the top face. Before starting an inside opening, drill a starter hole large enough for the blade.
Insert the blade through this hole, place the shoe firmly on the work, then start the cut. Never start with the teeth pressed against the material, because the saw may jump backward.
Speed control is about more than finishing a task quickly. A fast blade setting can work well in soft wood, while hard plastic may melt if friction creates too much heat. Slow, steady movement helps the material stay cool.
On a curve, make gentle turns rather than twisting the saw in one place. For a sharp corner, cut toward it from two directions or make relief cuts into waste material.
Real projects include cutting shelves around pipes, making holes for electrical boxes, shaping signs, and fitting countertops around sinks. Mark the waste side clearly, clamp the work securely, wear eye protection, and wait for the blade to stop completely before setting the tool down.
Key Facts
- Blade speed is often measured in strokes per minute, written as SPM.
- Cutting time can be estimated by t = L / v, where L is cut length and v is cutting speed.
- Blade tooth spacing is described by teeth per inch, written as TPI.
- Higher TPI blades usually give smoother cuts but remove material more slowly.
- Power can be estimated by P = E / t, where P is power, E is energy, and t is time.
- Orbital action makes the blade move slightly forward on the upstroke, increasing cutting speed but often making the cut rougher.
Vocabulary
- Jigsaw
- A portable power saw with a narrow reciprocating blade used to cut curves, shapes, and openings in materials.
- Reciprocating motion
- A repeated back and forth or up and down motion, such as the motion of a jigsaw blade.
- Kerf
- The slot or width of material removed by a saw blade during cutting.
- TPI
- Teeth per inch, a measurement of how closely spaced the teeth are on a saw blade.
- Orbital action
- A jigsaw setting that moves the blade in a small oval path to cut faster through some materials.
Common Mistakes to Avoid
- Using the wrong blade for the material, which can cause rough cuts, broken teeth, overheating, or unsafe binding.
- Forcing the jigsaw forward too quickly, which bends the blade and makes the cut wander away from the marked line.
- Starting a cut without clamping the workpiece, which lets the board vibrate and reduces accuracy and control.
- Cutting tight curves with a wide blade, which causes twisting and may snap the blade because the blade cannot turn sharply enough.
Practice Questions
- 1 A jigsaw cuts along a curved path that is 1.8 m long at an average cutting speed of 0.06 m/s. How long does the cut take?
- 2 A blade has 12 teeth per inch. How many teeth are along a 3.5 inch section of the blade?
- 3 You need to cut a smooth curved shape in thin plywood for a visible project part. Explain whether you would choose a high TPI or low TPI blade, and whether you would use strong orbital action.