Table Saw Blade Guards, Riving Knives and Splitters

OSHA's standard sets out what a guard must do: enclose the blade above the table and above the material, adjust itself to the thickness of the work while staying in contact with it, offer little resistance to feeding, and protect the operator from flying splinters and broken teeth. Since UL 987's 7th edition took effect in 2010, the voluntary standard has called for a modular guard — attached to a riving knife, with independent top and side barriers and openings so the cutting edge can be seen. UL 62841-3-1 allows either that or an over-arm guard.

SawStop's guard is typical of the modular kind: a clear polycarbonate shell that floats on the work up to 3-1/8 in high, with a limit rod to stop taller stock entering it and a dust port at the back. SawStop's conditions for it are that the shell and its side pieces pivot freely and stay clean enough to see through; if any part stops working, repair or replace it before using the saw. The CPSC found that people take guards off — to see better, or for certain cuts — and that injuries did not fall as modular guards spread. A guard that is on the saw is the one that works.

Both are thin steel plates behind the blade that run in the kerf. DEWALT describes them as plates that fit into the cut and fight kickback by lessening the tendency of the blade to bind; SawStop says its spreader keeps the work from pinching or shifting into the back of the blade; the CPSC that a riving knife keeps the two halves of the cut from moving back together. OSHA requires a spreader to be thinner than the kerf, stiff enough not to be pushed aside, and to stay aligned with the blade when the blade tilts.

• The difference is height. A splitter stands above the blade and usually carries the guard, so it must come off for any cut that does not go through the work. A riving knife sits below the top of the blade — UL 62841-3-1 places it behind the blade at a height that lets it pass through the cut — so it can stay on for rabbets and similar cuts. SawStop's knife sits inside the kerf with its top 1–5 mm below the blade's top.
• Thickness. The knife must be thicker than the blade's body and thinner than its kerf. DEWALT marks the range on the knife — see table saw blades for checking a blade against it.
• Gap. SawStop requires at least 4 mm between its knife and the blade at every point. Its European manual gives 4–8 mm for the same saw.
• Alignment. DEWALT checks its knife with a straightedge laid against two blade tips: the knife must not touch it. A bent knife is replaced or straightened before use, SawStop says.
• Not for dadoes. SawStop: neither the guard nor the riving knife can be used for dado cuts; featherboards hold the work instead.

Pawls are toothed arms on the splitter or knife that let the work slide forward and resist it moving back. OSHA calls for them on hand-fed ripsaws in workplaces. DEWALT's check before ripping is to push wood under them: the teeth must stop it being pulled back toward the front of the saw. Know their limits. DEWALT warns that in hard, slippery materials such as plastics and laminate the pawls may not stop a kickback, and that pawls and knife cannot help with work too short to engage them. When a cut-off piece is held under a pawl after a cut, SawStop says to turn off the motor and wait for the blade to stop before pushing it past.

A brake is not a guard. SawStop's system detects contact with the body and stops the blade in about 3 to 5 milliseconds; it can still leave an injury, and SawStop calls it a last measure for when every other precaution has failed. The brake cartridge cannot be reused once it has fired — SawStop says to fit a new one. The CPSC record describes two other systems, Bosch's REAXX and Felder's preventative contact system. UL's attempts to add performance requirements for such systems to its standards failed in ballot, and the CPSC withdrew its own proposed requirement in September 2025, so the guard, knife and pawls remain the protection every saw has.