The quality of a router bit can be the difference between a great woodworking project and a botched one. It doesn't matter how much experience you have -- a bad router bit will give you a bad cut every time, and there's not much you can do about it.
There are two materials that are used to make router bits -- HSS and carbide. Carbide bits are much more expensive, but they can last 20 times longer than HSS. HSS bits tend to become dull quickly. When this happens, you start burning your wood instead of cutting through it smoothly. If you use your router only a couple times a year, you can get away with using HSS bits, but if you plan on using it every day, or even every weekend, you may want to invest in some durable, long lasting carbide bits.
Quality router bits will stay sharp for a long time. Make sure the cutting edge of your bit is fine. It should be smooth to the touch without any chips. Thicker cutters will also allow you to regrind the bit a number of times, greatly extending its life. When buying carbide-tipped bits, be sure to inspect them carefully. If it looks like the carbide is being held on by poor craftsmanship, steer clear. There shouldn't be any nicks or dips in the surface of the bit that aren't meant to be there. The bit should look new. This seems obvious, but look closely -- some bits may have rust on them. It's also important that the surface of the bit is smooth. If it isn't, it'll collect debris over time and slow you down.
To quickly recap, bits should be sharp, smooth and finely ground. A better bit will cause less vibration. Quality bits equal quality cuts and good ones should last you a long time if properly used.
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