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Identifying Router Bits for Use on a Plunge or Fix-Base Router

Q: I am now the proud owner of a plunge router. How do I choose the right bits for it? I’ve checked several displays at the home centers, and there are no clear divisions between “fixed” and “plunge” bits. Identifying a straight plunge router bit Plunge bits are easily identified by the shape of their cutting edge as it crosses over the tip of the bit and ultimately, the hole they cut. A: Identify a plunge-cutting bit by looking for a cutting edge that crosses the tip. The carbide-cutting tips of the bit on the left jut above the steel body, which is flat on top. Plunge it and only the tips cut: when the steel hits the wood, it stalls the cut. It’s not a plunge-cutting bit. The bit on the right has an extra carbide-cutting tip crossing its tip. The maker identifies it as a plunge-cutting straight bit, and the extra carbide makes it more expensive than a more conventional straight bit of the same diameter. The commonplace design for straight bits is seen in the middle. The steel body between the carbide tips is ground to form a ridge. It may not be particularly sharp, and it may not seem to be a cutting edge in the conventional sense, but the shape is sharp enough to enable the bit to plunge. You can buy bearing-free profile bits that cut grooves, and these bits will plunge. A core-box bit is a coving bit without a pilot. A V-groover is a chamfering bit without a pilot. Shop around and you'll find pilot-free, plunge-cutting bits that form roundover and ogee profiles. All of these bits have cutting edges extending across the bit’s tip.