What a Shank and a Chuck Do
The shank is the end of a bit that the drill holds. The chuck is the part of the drill that grips it. Both need to match. A good match keeps the bit centred, transfers torque without slipping and, in some systems, allows hammering action to pass through.
Common Shank Types
Straight (Round) Shank
The most familiar type. The shank is a plain cylinder, usually the same diameter as the cutting part or slightly smaller. It works in standard three-jaw chucks. Larger bits may have a reduced shank so they fit a smaller chuck.
A drawback is slip. Under heavy load, a smooth round shank can spin in the chuck jaws, which can mark the shank over time.
Hex Shank
A hex shank has six flats. The common quick-change size is 1/4 inch. Hex shanks grip well in impact drivers and in quick-release chucks. Many wood and metal bits are sold with hex shanks for use with impact drivers; check that the bit is rated for impact use, since not all are.
Reduced Shank
Large-diameter bits sometimes have a narrower shank so that they fit a common chuck size. The shank is smaller than the cutting diameter, so check the shank size against the maximum chuck capacity.
SDS-Plus and SDS-Max
These grooved shanks are for rotary hammers; see types of SDS drill bits. SDS-Plus has a shank about 10 mm in diameter, and SDS-Max is larger, about 18 mm. They are not interchangeable without an adapter designed for the purpose.
Morse Taper
A Morse taper is a conical shank that wedges into a matching socket in a drill press or lathe spindle. Taper sizes are numbered (for example MT1, MT2). They give strong and accurate holding for large bits in heavy machinery. Bits are usually removed with a drift or a release mechanism.
Other Shanks
Larger systems exist for industrial work, such as larger hex shanks (sizes vary by maker) for heavy-duty breakers and spline drive shanks. Older braces use square tapered shanks. These are less common in home workshops.
Chuck Types
Keyed Chuck
A keyed chuck is tightened with a small key. It gives a strong grip and is common on drill presses and corded drills. You need to keep the key with the tool and remove it before drilling.
Keyless Chuck
A keyless chuck is tightened by hand. It is convenient and now common on cordless drills. Single-sleeve and double-sleeve designs both exist. Quality varies, and some may loosen with heavy use.
SDS Chuck
An SDS chuck is a spring-loaded system with locking elements. The bit slides in and locks without tightening a collar. It is only for SDS shanks.
Quick-Release Hex Chuck
An impact driver or drill with a quick-release hex collar takes bits with a 1/4 inch hex shank. You push the bit in and it locks.
How to Match Bits to Your Drill
- Identify the tool. Drill/driver, impact driver, hammer drill, rotary hammer or drill press.
- Read the chuck capacity. It is often shown on the chuck or in the manual, for example 3/8 or 1/2 inch.
- Check the shank. Make sure it is compatible with the chuck.
- Think about the task. Impact use calls for impact-rated bits.
Adapters can help. For example, a chuck adapter can let a conventional bit be used in an impact driver, and an SDS adapter can let a keyed chuck sit on a rotary hammer. Adapters add length and play, and they can reduce precision. Use them with caution.
FAQ
What is the most common drill shank size?
The most common are the 1/4 inch hex shank for driver bits and round shanks that fit the 3/8 inch and 1/2 inch chucks found on most drills. Regional sizes vary, particularly metric.
How many shank types are there?
There is no single agreed number. Common lists include straight, hex, SDS-Plus, SDS-Max, Morse taper, reduced, and several less common types.
What are the three types of drill chucks?
Often listed as keyed, keyless and SDS, though some sources use different groupings.
Can I use an SDS bit in a regular drill?
Generally no, apart from special adapters. The grooves are for an SDS chuck.
For an overview of the bits themselves, see the drill bit types guide.