What are the different types of drill shanks?

There are many different forms of drill bit shanks used on various types of drill bit pieces and sets. This article covers the 9 most common drill bit shanks that consumers can purchase: Straight Shanks, HEX Shanks, SDS Shanks (including its variants), Reduced Shanks, Brace Shanks, Traingle Shanks, Square Shanks, Morse Taper Shanks and Threaded Shanks. Each type of shank serves a different purpose and result when combined with its intended drill bit and surface material.

What is a Drill Bit Shank?

A shank of a drill bit piece is the end clamped by the chuck of a handheld (or hand-held) drill tool device or drilling machine. The drill bit shank provides the drive of the drill into a workpiece surface material. Typically tapered in shape, allowing for an easy intertion into the drill chuck. Whilst the upper end of the shank is usually flat and is sometimes known as “the tank”.

Straight Shank

The most common form of shank used on the majority of standard drill bits. This style is often used on the everyday Jobber Twist Drill Bits used for DIY Drilling and General Drilling Construction Processes. Typically held by a three-jaw drill chuck, the drill bit is often the same size diameter from shaft to shank. Sometimes a drill bit may have a shank with a larger diameter to allow for drill bits of a smaller diameter to grip firmly within the chuck. Straight Shank Drill Bits have the ability to be used in any collet chuck providing that the chuck can be tightened to grip/clamp the drill bit, this makes them particularly good for smaller sizes. Straight Shanks allow for precise centering as well as minimal turn cycles and grind rotations, they are the ideal solution for any turn on a lathe. A drawback with Straight Shanks is that the torque transmission can be limited due to the slipping of the cylindrical shank.

HEX Shank (Bit Shank)

Drill Bits with a HEX Shank often have flat edges within the bar stock of the shank, this allows it to be mounted within specific chuck with hex shanks, hex screwdriver bit chucks, machine screwdriver bits and drill bits compatible with screwdriver machinery, alongside drill chucks made for cylindrical shanks and standard three-jaw drill chucks. HEX Shanks however do not allow for fixtures to standard round collets, instead a 3c or 5c special HEX collet is required. HEX shanks are ideal for providing high torque transmission without a need for tightening the shank into the chuck (due to the HEX Shape).

SDS Shank

There are various different size forms of SDS Shanks, the most common pair are SDS-Plus and SDS Max. SDS is an abbreviation of Slotted Drive Shaft, developed by Bosch in Germany in the 1970s as a development of the former TE System developed by Hilti in the 1960s. Circular in design, they have square slots at the end to allow them to be fitted and best suited for Hammer Drills. Unlike standard Stright Shanks, SDS have specialised slotted shanks that do not require tightening, instead, simply insert it into the SDS hammer drill's designated slots, and it will remain in place. Drilling the hole using an SDS drill bit ensures that you will go all the way through hard surfaces such as concrete faster and more efficiently. 

SDS-Plus (or SDS Plus) is interchangeably with regular SDS and simply offers an improved connection. It has 10 mm shanks with four slots that hold it more securely.

SDS Max has a larger 18mm shank with five slots used for bigger holes. However, it is not interchangeable with the SDS and SDS PLUS drill bits. They are typically used on larger rotary hammers and chipping guns.

Other forms of SDS include SDS Quick - with a much smaller 6mm Shank Diameter over the 10mm size of the standard SDS Shank, SDS Top (or SDS-Top) – a Shank variant that is generally being phased out and was predominately used for , SDS-TE-S – an evolution of the original Hilti TE-S, used for chisels and scrapers in chiselling or demolition of concrete applications and Spline – a larger 19mm shank and splines that hold the bits tighter.

The shanks of SDS and SDS-Plus drill bits are interchangeable and have a diameter of 10 mm. Unfortunately, the spline is not compatible with SDS-MAX drill bits. However, you can find after-market adapters so that you can use these drill bits interchangeably.

Reduced Shank

A Reduced Shank Drill Bit (also commonly known as a Blacksmith Drill Bit) shares a lot of similar properties to the everyday standard Straight Shank Drill Bit. However, these drill bits with these shanks are usually much larger in diameter of drilling hole size) whilst being narrower than the drill diameter (unlike the straight shanks same size throughout). This is because they can then be fitted to chucks that are unable to chuck the full diameter, due to the large size of the drill bit. Reduced Shanks often face the same issues as Straight Shanks with limited torque transmission due to the cylindrical shape of the shank.

A variation of the Reduced Shank Drill Bit known as the Silver & Deming (S&D) Drill Bit is sized slightly differently to that of other reduced shank drills. These run from ⁹/₁₆ – inch (14mm) to 1½ – inch (38mm) in drill body diameter and typically have a standard ½ - inch (13mm) reduced shank. Allowing for a drill press of ½ - inch (13mm) chucks to run the larger drills.

Morse Taper Shank

Generally used in metalwork activities, these shanks are mounted directly into the spindle of the drill/milling machine, self-locking (or sometimes referred to as self-holding) to allow the torque transfer in the drill bit by friction between the taper shank and the socket. This maintains a high torque transmission and hard drive into a workpiece. Whilst these Shanks are simple to manufacture on a lathe machine/device, they do have a disadvantage of not being compatible with chucks or collets.

Brace Shank

A slightly outdated form of shank found on a drill bit is the Brace Shank. This drill bit is less common today (but still in use) and was particularly favourable up until 1850 when drill chucks and drill bits evolved with the changing of the times (most notably with the Industrial Revolution). These shanks have a more old fashioned grasp compared to modern equivalents as the shank has no specific design and shape to be clamped into the chuck and is typically forced into a square holed end of a drill.

Triangle Shank

Triangle Shanks earn their name due to the 3 flats machined into the round bar stock, providing a triangular shape. A minor modification to the common Straight Shank, these shanks are held by a three-jaw drill chuck. However, unlike straight shanks, these shanks provide a higher torque transmission and have limited slippage. Thus, giving a more powerful, stronger, sturdier and more accurate drilling result in harder materials. A drawback to these drill shanks is that they cannot be held in a collet unlike the Straight Shank.

Square Shank

Ideal for larger ratchet drills, these shanks have a strong ability to drill large holes and into thick plates. When used in a ratchet drill, the bit should go straight into the ratchet drill, then with pressure applied against the work piece, as long as the ratchet drill is used against a strong arm.

Threaded Shank

A rare type of shank, suited for tight hard to reach applications. Designed for wire wheels and large wood drills. For example, pipe cleaning uses cylindrical wire wheels to push into the insides of a pipe.

Threaded Countersinking Tools use these shanks for creating holes that allow for a rivet (that matches the tool) flush within a surface material. This is a common practise within aircraft metalwork applications.

Quality Tools UK supply a range of drill bits from RUKO and TERRAX by RUKO with a variety of drill bit shanks, providing a range of drill bits for any drilling device hand-held or machine to pierce a hole into the majority of surface materials dependant on the surface requirements. You can order our drill bits online here at www.qlt.tools with Free Delivery (for UK based businesses or residents) on orders over £50.