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Along the back edge of one of my workbenches is a dusty collection of inexpensive, ineffective, high-speed steel router bits that I'll never use again. I bought them as a novice, and even though they did almost nothing for me before getting dull, I've kept them around since 1981 as a reminder to buy good tools or don't buy at all.
The temptation to choose cheap is especially strong for beginners building a router bit collection. With so much to buy, it seems silly to pay $50 for a top-quality carbide router bit when you can get the same shape of high-speed steel bit for just $10. After all, you're not outfitting a professional workshop, are you?
The truth is, that $50 carbide bit really will last a lifetime; the high-speed steel alternative might only be good for a project or two. Which is cheaper? And then there's the question of results. The best carbide bits cut clean, crisp profiles that do justice to the finest wood. But the moment a high-speed steel bit gets dull (and that happens fast) it'll set off the smoke alarm in your workshop as it leaves streaks of blackened wood behind.
The term carbide refers to an extra-hard alloy that retains its sharp cutting edge under tough conditions. High-speed steel is a softer, less durable material. And although it's fine for drill bits, it just can't handle the friction and wear that develops as it chews through wood at 20,000 rpm.
The two bits on the right have carbide inserts brazed to softer steel bodies; the spiral bit on the left is made entirely of carbide. The angled cutting edges on this bit make it especially good at augering out wood chips while milling grooves in wood. The best circular saw blades also have carbide teeth brazed around their edges, offering the same long life and excellent performance.
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But as tough as carbide is, it still needs to be resharpened, usually after a couple of years of home workshop duty. That's how you squeeze a lifetime's use from them, though sharpening isn't something you can do on your own. The degree of grinding precision required to maintain balance at the high spinning speed of a router bit is something that can only happen in a specialized machine shop. And although there are probably dozens of capable carbide shops across the country, I've only used one over the years. The best are set up to handle mail-order processing across the country and I've always been please with the results. Got a gunky-but-sharp bit? Oven cleaner does a great job removing the resins that build up when you shape soft woods. Clean them outside with a tooth brush, rinsing the cleaner off with water. Wear safety glasses.
There's another feature of router bits that may save your fingers some day. The bit shown in the middle has an anti-kickback feature that you should look for in any new router bit you buy. This is a design standard that originated in Europe to lessen the chance of kickback -- the sudden and uncontrollable flinging-back of a work piece as it's grabbed by a spinning router bit. The fuller-than-normal body shape of an anti-kickback bit reduces the amount of carbide cutter exposed to the work piece. This lessens the chance that the bit will bite off more wood than it can chew -- a condition that leads to the kickback event. But don't worry. This bite-limiting effect doesn't interfere with the normal performance of a bit. Anti-kickback hardware still cuts as effectively, it just helps keep you out of trouble.
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