The blade does most of the work
When a jigsaw cut comes out ragged, burned or off the line, the blade is a more common cause than the saw. Blades are inexpensive compared with the tool, and changing to the right one often improves a cut more than any adjustment. Because blade lineups vary a lot and models change, this article explains what to look for rather than naming products.
Shank type: will it fit?
The shank is the end of the blade that fits into the saw. Two styles are common:
- T-shank: Has a tab shape at the top and is used by many current saws with tool-free blade clamps.
- U-shank: Has a U-shaped notch and is found on older saws or some lower-priced models.
Many saws accept only one type, so check the manual before buying. Using the wrong shank can mean the blade does not seat securely, which is both frustrating and unsafe. Some saws accept both; confirm this in the manual rather than guessing.
Tooth count
Tooth count is usually given as teeth per inch (TPI), and the rule of thumb is simple:
- Fewer, larger teeth (lower TPI) remove material quickly and leave a rougher edge. They suit thick wood and fast, rough cuts.
- More, smaller teeth (higher TPI) cut more slowly and leave a smoother edge. They suit thin stock, laminates and metal, where several teeth should be in the material at once.
A general guide is to have at least a few teeth engaged in the thickness of what you are cutting. Very thin sheet metal, for example, often calls for a fine-toothed blade, because large teeth can catch and tear the edge. Exact numbers vary by manufacturer, and packaging usually states the intended material and thickness.
Tooth shape and set
- Ground teeth are sharpened more finely and generally cut cleaner but more slowly.
- Milled teeth are cut more aggressively and cut faster with a rougher result.
- Reverse-tooth (down-cutting) blades point their teeth downward, so they cut on the downstroke. These tend to reduce splintering on the top face but can chip the underside, so they are sometimes used for laminate with the finished side facing up where the manufacturer recommends it. Check the packaging.
- Wavy set teeth, bent side to side in a wave pattern, are common on metal-cutting blades to help the blade not bind in thin material.
The set, or side-to-side offset of the teeth, determines how wide a slot the blade makes. Understanding saw kerf helps explain why a wider kerf takes more material and why a thicker blade can follow a line more steadily but turns tight curves less easily.
Blade materials
- High carbon steel (HCS): Common for wood and some plastics. It is flexible, affordable and dulls more quickly, especially in abrasive materials.
- High-speed steel (HSS): Holds an edge better, which suits metal and harder material. It can be more brittle than HCS.
- Bi-metal: Combines a flexible body with hardened teeth. A popular choice when you cut both wood and metal, including wood that might contain nails, though a nail can still damage the teeth.
- Carbide-tipped or carbide-grit: Very hard and used for abrasive or hard materials such as tile, fiber-cement board, or fiberglass. Grit blades do not have conventional teeth and cut slowly, leaving a rough edge.
Harder materials generally last longer but cost more and may snap rather than bend if the saw is pushed sideways. Pairing the blade with the right metalworking tools and speed settings matters for metal.
Blade width and thickness
Narrow blades turn tight curves more easily. Wider blades resist flexing and track straighter. For scroll work or small-radius curves, pick a narrow scrolling blade; for straight or gentle cuts, choose a wider and stiffer one. Cutting thick material with a thin blade is a frequent cause of cuts that lean away from vertical.
Matching blade to job
| Job | Typical choice |
|---|---|
| Rough cuts in thick softwood | Lower TPI, aggressive teeth |
| Clean cuts in plywood or veneer | Higher TPI, ground teeth, often a clean-cut design |
| Tight curves | Narrow scrolling blade |
| Laminate or coated panels | Fine teeth, sometimes reverse-tooth |
| Sheet metal | High TPI, bi-metal or HSS |
| Tile, fiberglass or cement board | Carbide-grit |
| Plastic | Medium to fine teeth, slower speed |
These are general starting points, not rules. Always read the blade packaging for what it was designed to cut.
Getting more from each blade
- Slow the saw down for metal and plastic, as heat can melt plastic against the blade and dull steel quickly.
- Use lower orbital settings for clean cuts and higher ones for fast rough cuts.
- Replace a blade when it burns the wood, needs more force, or starts to wander. A dull blade does not improve with force.
- Keep blades dry and store them where the teeth will not be damaged.
Safety
Blades can break, so wear eye protection. Unplug the saw or remove the battery before changing a blade, and never touch the teeth of a blade that has just been used, because it can be hot. Handle new blades carefully and store them in their packaging so teeth are not exposed. Follow your saw’s manual for how to install a blade.