Drill Bits

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• Twist-drill bits: Twist-drill bits are used in both wood and unhardened metals to make clearance holes for bolts, screws, etc., and to make holes for tapping. Only bits marked HS or HSS are suitable for drilling in metals. Common sizes run from 1/16" to 1/2" diameter by 64ths. Twist bits are usually marked in the same manner by 64ths of an inch. Thus a No. 8 bit would stand for 8/64" or 1/8".
   

• Auger bits: Auger bits are most commonly used with a brace for drilling holes in wood. Their length varies from 7" to 10". Dowel bits are short auger bits from 5" long. Long (ship) auger bits range from 12" to 30".
   

• Expansive bits: Expansive bits take the place of many larger bits. They are adjusted by moving the cutting blade in or out by a geared dial or by a lock screw, to vary the size of the hole. These are mounted below the surface for a finished appearance.
   

• Forstner bit: Used to form holes with a flat bottom, and used best in a power drill held in a drill stand.
   

• Hole saw: These drill bits are used for cutting large, fixed, diameter holes in wood or plastic. They can cut up to a depth of 18mm or more.
   

• Glass and Tile Bits: They are designed specially for smooth, accurate drilling in marble tile, ceramic tile, mirrors and glass.
   

• Step drill: These type of drill bits are used to enlarge holes and also for drilling a variety of perfectly sized holes in thin gauge metal, wood, plastic and PVC.
   

• Countersunk bits: Countersunk bits widen holes, so flat-head screws may be flush-mounted below the surface, for a finished appearance.

• Masonry bit: Used in power tool, they are used to drill brick, block, quarry tiles, stone or concrete.