Drill Bits

For those who’ve rarely used a drill, all drill bits tend to look the same. And yet… depending on the material to be drilled, the type of drill being used and the dimensions of the hole to be cut, there are as many different types of bits as there are applications.

Drill bits are made up of two separate elements: the shank; and the cutting element (or the actual bit).
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Drill Bit Shank versus Drill Chuck
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Drill Bit Shank versus Drill Chuck

The shank is the non-cutting end of the drill bit that is inserted into the drill.

The chuck is the mechanism on the drill that clamps onto the bit by its shank to secure it in place while it is rotated. Standard chucks are often comprised of three "jaws" that spread apart or come together depending on whether the chuck ring is tightened or loosened. There are also chucks designed for hex shanks and SDS shanks (see below).

Standard or Straight Shank

The most common shank on the market, the standard (or straight) shank has a cylindrical body that is usually* the same diameter as the cutting end (twist drill bits and brad point bits). Designed exclusively for use with standard chucks.

This type of bit provides superior precision in terms of guidance/centering but is limited in terms of allowable torque.

* To ensure proper operation with a standard chuck, smaller drill bits may be manufactured with an oversized shank while larger diameter bits may come with a reduced shank.

Hex Shank

Instead of the cylindrical shape featured on the straight shank, the hex shank features a six-sided insert – hence its name. The hex shank is obviously designed to work with a hex chuck but it may also be used quite effectively with a standard chuck. And, though it is not as precise as the twist drill in terms of guidance, the shape of the hex shank prevents the drill bit from slipping and allows it to provide significant torque.

SDS Shank

This type of shank, which allows the user to insert a bit using only one hand, is made specifically for percussion drills. SDS shanks are not locked into position but are designed to slide up and down within the chuck (they require greasing as a result).

They are considered the most effective shank to use with percussion drills, for drilling holes in stone and concrete using a masonry bit. Though the SDS shank may lack precision, keep in mind that drilling stone and concrete does not generally require significant precision.

SDS shanks come in three sizes: SDS, SDSplus (or SDS+) and SDS-Max. The most common size is SDSplus.
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