Q: I always read about them in table saw reviews, but I never seem to see them in my friends’ shops. So what’s the story with riving knives … do I really need to have one on my table saw?
A: A riving knife is a splitter that sits behind a table saw blade. Its job is to prevent kickback that results from stock distortion — a not uncommon event that can occur during ripping operations. While all riving knives are splitters, not all splitters are riving knives. The quintessential riving knife is curved to match the diameter of the saw blade and “hugs” the back of the blade, with a distance of 1/8" to 1/4" between blade and knife. The top of the riving knife is held just below the top of the saw blade, so it does not interfere with cuts or grooves formed by the blade. But here is the most important characteristic: It is mounted in such a way that it will rise and lower with the blade as it is adjusted for various cuts.
Many experts feel that a riving knife is the single most important piece of safety equipment a table saw can sport. A properly used riving knife alone will eliminate nearly all ripping kickback — one of the primary causes of table saw injuries. When it’s used in conjunction with proper technique (blade height, stance, push sticks, etc.) and blade guards, nearly 100 percent of table saw mishaps can be avoided.
Riving knives have been standard equipment in Europe for decades but have been largely and inexplicably absent from U.S. table saws. Recently, a group of power tool industry manufacturers joined together to create a new standard for table saw safety equipment that includes quality riving knives (as well as easy-to-operate top guards), even on small portable saws. Some within the industry contend that this new focus on safety was sparked by SawStop’s table saw with its high-tech saw blade brake — an important new player in this market.