How do you evaluate router-bit quality?
When I shop for a new router bit, the only obvious differences are color and price. What should I look for to evaluate the quality of a particular bit?
—Will High, Salem, Oregon
First, Will, look for carbide bits rather than high-speed steel. They cost more, but hold their edge much longer. For the very top of the line, seek out bits labeled as having micrograin carbide. Before buying a particular bit, perform a visual inspection to determine its quality. Check for the points detailed here and in the photo above.
* General appearance: A well-made bit has cutting edges that gleam and displays no gaps where those edges are brazed to the bit body. Be sure the cutting edges are free of tiny chips.
* Size: Choose bits with 1⁄2 " shanks if your router accepts that size. The extra mass produces a smoother cut and should never break or bend during normal use. Also select bits with plenty of metal behind each cutting edge; besides supporting the edge, this design prevents kickback caused by fast feeding and deep bites.
* Sharpness: Turn a bit against your fingernail and it should easily skim off a shaving. If not, it hasn't been sharpened properly and won't give the results you want.
* Dust protection: Bits with pilot bearings perform better and last longer when they include a dust shield between the bearing and the bit body. The shield helps to keep the bearing clean and turning smoothly.
* Configuration: Bits with two cutting edges surpass single-edge bits in making smooth cuts. Also flutes set at a slight angle to the shaft, as shown in the photo above, slice wood fibers instead of chopping them, which generally gives better results.