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Power Bore Bits
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power bore bitsIf you’ve ever had to drill a few deep holes in hardwood with a standard twist bit, it may have gone something like this: Drill, bind, back out of the hole. Drill, burn, bind, back out. Drill, burn, bind, stop, unscrew the piece of wood from the drill bit and pick the chips out of the flutes. Drill, bind, back out…

The problem is that twist drill bits – the kind most of us are used to seeing – weren’t designed with woodworking in mind. They have one of the simplest geometric designs of all drill bits, making them inexpensive to manufacture, and are really designed for “general purpose” drilling. When it comes to drilling wood – especially deep holes - their narrow flutes have trouble keeping up with the chip ejection demands, and the relatively large amount of surface area that stays in constant contact with the wood causes enough friction to make burning difficult to avoid.

Rockler’s Power Bore Bits were designed to answer a number of the shortcomings of typical twist bits. Most notably, they have a patent-pending that simultaneously reduces the friction-creating surface area of the bit that comes in contact with the wood, and provides deep enough flutes to facilitate the kind fast chip ejection you need when you want to drill a few deep holes in a hurry. Because of that, they can cut through a thick piece of burn-prone hardwood in a couple of seconds, without binding or causing other problems.

Power Bore bits also incorporate the best of the features of bits that actually were designed for drilling wood. Like “brad point” bits and other woodworking drill bits, they have centering point, which makes it easy to position the hole exactly where you want it. They share their basic cutting geometry with the forstner bit, a bit design that has been synonymous with crisp, precise drilling since the late 1800s. Just like a forstner bit, the Power Bore bit’s perimeter spur shears off wood at the edge of the bore, making for a nearly perfect hole-edge, while the horizontal radial cutter planes off material from the bottom of the hole and propels it upwards through the flutes. The result is an exceptionally crisp cut and a nearly flat bottomed hole in a short amount of time.

Are Power Bore Bits “the only bits you’ll ever need”? Not necessarily. They aren’t for drilling metal, for one thing. And forstner bits are still the only logical choice for precision drilling in diameters larger than ¾’’.  But they do make everything from everyday punching holes in wood to more exacting work like doweling or drilling out material for a mortise fast, easy and actually kind of fun.

posted on May 3, 2007 by Rockler
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3 thoughts on “Power Bore Bits”

  • Matt

    I noticed that your set only comes in diameters up to 11/16'. It seems that a bit of this design would be ideally suited for larger diameters. Why aren't there larger sized available. Irwin's Speedbor Max sets are very similar and go up to 1'1/4". Come out with one in 1 1/2" and I'll buy it.

  • Rockler Blog Team
    Rockler Blog Team December 31, 2008 at 9:51 am

    Good question, Matt. Actually, the set comes with bits up to 3/4". We'll have to get back to you on why that's as large as they go.

  • John

    I am looking for a bit that would allow me to drill into the end grain of a section of a tree branch. I am looking for a bit that is larger than 1.5 inches. My intention is to create rustic candle holders where a tea candle is placed in the .05 inch deep hole on the end of the section of the tree branch. I have been using a 1.5 inch spade bit to do this, but unfortunately wood swells and contracts and once that happens the tea candle no longer fits into the hole. I would be interested in trying a power bore bit if there were a bit available in 1.625/ or 1 & 5/8 or 1.750. Thus I am curious if there are power bore bits made in sizes larger than 3/4 as per the question from Matt in 2008.

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