ToolsArmenia Knowledge BaseTypes of Tool Chucks and Their Applications The chuck is the main connection between a power tool and its working accessory. The correct chuck determines compatibility, retention, working accuracy, and the permitted load.Reading time: about 15 minutesUpdated: July 2026ToolsArmenia Editorial Team Table of ContentsWhat a chuck isKeyed and keyless chucksSDS Plus and SDS Max chucksHEX and square drivesFastening-system comparisonCompatibility and adapters6 selection stepsCommon mistakesFrequently asked questions What Is a Tool Chuck?A chuck is the fastening unit between the tool spindle and its accessory. It centres and retains a drill bit, driver bit, masonry bit, core bit, or other accessory and transfers rotational or impact loads.The chuck must match the tool mechanism, accessory shank, and intended work. Accessories with the same working diameter can have different shanks and may not fit the same chuck.Important distinctionA drill chuck, a 1/4″ HEX quick-release holder, and a 1/2″ impact-wrench square drive are different fastening units designed for different tasks. Three-Jaw Chucks: Keyed and KeylessThree jaws move evenly toward the centre and clamp a cylindrical or certain hexagonal shanks. Common capacities include 1–10, 1.5–13, and 2–13 mm, but the exact range must be read from the specific chuck.Keyed chuckThe jaws are tightened with a separate key. It provides strong, controlled retention, especially with large drill bits and higher loads.Keyless chuckTightened by hand using one or two sleeves. Accessories can be changed quickly without a separate key.Single-sleeve keylessSuitable for tools with a spindle lock: the spindle is held while the chuck is tightened with one hand.Double-sleeve keylessOne sleeve is held while the other is turned. Suitable for tools without an automatic spindle lock.Hammer-mode limitationNot every keyed or keyless chuck is designed for a hammer drill. Check impact resistance and suitability for reverse rotation. SDS Plus and SDS Max ChucksAn SDS chuck accepts drill bits, chisels, and other accessories with a grooved SDS shank. The accessory locks without jaws or a key. The design permits limited axial movement required by a pneumatic hammer mechanism.SDS PlusUsually a 10 mm nominal shank system for light and medium rotary hammers, small and medium holes, and limited chiselling.SDS MaxUsually an 18 mm nominal shank system for heavy rotary hammers, large drill bits, core bits, and intensive demolition.Interchangeable chuckSome rotary hammers allow the complete SDS unit to be quickly replaced with a three-jaw keyless chuck for wood or metal drilling.SDS adapterAn adapter with an SDS shank can carry a conventional chuck, but it adds length and is generally not intended for full pneumatic hammer operation. HEX Quick-Release Holders and Square Drives1/4″ HEX quick-release holderUsed mainly on screwdrivers and impact drivers. It accepts compatible hex bits and allows quick changes through a locking sleeve.Demolition HEX systemsHEX systems of 17, 19, 28, 30 mm, and other sizes are used on demolition hammers. They are not one universal standard: shank size, length, and locking geometry must match.Square drives: 1/4″, 3/8″, 1/2″, 3/4″, and 1″A square drive is normally the anvil of an impact wrench and accepts an impact socket of the same drive size. Retention may use a ball, friction ring, or pin. It is not a drill chuck and does not directly clamp a conventional drill bit.Simple ruleUse 1/4″ HEX for bits, a matching square drive for sockets, SDS for concrete drilling, and a three-jaw chuck for cylindrical drill-bit shanks. Chuck and Fastening-System ComparisonTypeCompatible accessoryMain applicationKey feature Keyed three-jawCylindrical and some HEX shanks.Wood, metal, plastic, and general drilling.Strong clamping with a separate key.Keyless three-jawCylindrical and some HEX shanks.Drilling and driving with quick changes.Hand tightening without a key.SDS PlusSDS Plus shank only.Concrete drilling and light chiselling.Quick retention and axial movement.SDS MaxSDS Max shank only.Heavy drilling and demolition.Large unit for high loads.1/4″ HEX1/4″ HEX bits and accessories.Driving and impact fastening.Very fast bit changes.Demolition HEXExact-size HEX point or chisel.Breaking concrete, stone, and asphalt.High impact-load transfer.Square driveImpact socket of the same size.Tightening and loosening fasteners.High torque transfer. Compatibility, Threads, and AdaptersAppearance alone is not enough when replacing a chuck. Check the tool-side connection, such as 1/2″–20 UNF, 3/8″–24 UNF, B16 taper, SDS Plus, or a manufacturer-specific quick-change interface.The chuck capacity must include the accessory-shank diameter.The thread or taper must match the spindle exactly.A chuck for a reversible tool must have suitable retention.A hammer-drill chuck must be rated for hammer operation.A standard chuck on an SDS adapter is generally used without impact for wood or metal.A HEX or square-drive adapter does not turn a tool into a full substitute for another tool class.SafetyDo not use an accessory held only by the jaw tips or visibly off-centre. Poor retention can damage the jaws, create vibration, and allow the accessory to be ejected. 6 Steps for Choosing the Correct Chuck1Identify the tool typeDrills, rotary hammers, screwdrivers, impact drivers, impact wrenches, and demolition hammers use different interfaces.2Read the tool markingCheck the chuck type, clamping range, thread, taper, or special-system designation.3Check the accessory shankDistinguish cylindrical, SDS Plus, SDS Max, 1/4″ HEX, demolition HEX, and square-drive accessories.4Consider the operating modeRotation, hammer drilling, pneumatic impact, impact driving, and demolition impose different requirements.5Select the retention methodKeyless is convenient for frequent changes; keyed or task-specific systems may be preferable under heavier loads.6Check manufacturer limitsBefore using an adapter or interchangeable chuck, verify the permitted mode, speed, and load. Common Chuck Selection and Use MistakesChoosing only by the 13 mm capacity without checking the mounting thread.Using an ordinary keyless chuck in hammer mode without confirming impact resistance.Using a three-jaw chuck on an SDS adapter for pneumatic concrete drilling.Confusing 1/4″ HEX with large demolition-hammer HEX shanks.Using a non-impact socket on an impact-wrench square drive.Clamping a shank that is too small or incompatible.Failing to clean dust and metal particles from the chuck and shank.Leaving the chuck key installed before starting the tool. Frequently Asked QuestionsWhich is better: a keyed or keyless chuck?Keyless is convenient for frequent changes, while a keyed chuck may provide more controlled high clamping force. The correct choice depends on the task and chuck quality.Does a 13 mm chuck mean a maximum 13 mm hole?No. It generally means the maximum shank diameter the chuck accepts. Drilling capacity also depends on the tool.Can a standard drill bit be installed in an SDS chuck?Not directly. A compatible conventional chuck or adapter is needed, and the work is generally performed without pneumatic impact.Can one tool use SDS Plus and a keyless chuck?Yes. Some rotary hammers have quickly interchangeable SDS Plus and three-jaw chucks.Can a conventional drill bit be used with a 1/4″ HEX holder?Only a drill bit with a 1/4″ HEX shank or a suitable chuck adapter. A round shank does not lock directly into the holder.Is a 1/2″ square drive a chuck?It is normally an impact-wrench anvil for impact sockets, not a three-jaw drill chuck.Why does a drill bit wobble?Possible causes include poor clamping, worn jaws, a bent bit, spindle damage, or a low-quality adapter.Should a chuck be lubricated?Maintenance depends on the type. An SDS shank may require special grease; follow the manufacturer’s instructions for a three-jaw chuck. Read AlsoHow to choose handheld power tools.Differences between SDS Plus, SDS Max, and HEX.What is torque?What is impact energy?What is rotational speed?Related CategoriesDrills.Rotary hammers.Screwdrivers.Impact wrenches.Demolition hammers.Drill bits, masonry bits, driver bits, and sockets.Next article: How to choose disc diameter.
Keyed chuckThe jaws are tightened with a separate key. It provides strong, controlled retention, especially with large drill bits and higher loads.
Keyless chuckTightened by hand using one or two sleeves. Accessories can be changed quickly without a separate key.
Single-sleeve keylessSuitable for tools with a spindle lock: the spindle is held while the chuck is tightened with one hand.
Double-sleeve keylessOne sleeve is held while the other is turned. Suitable for tools without an automatic spindle lock.
SDS PlusUsually a 10 mm nominal shank system for light and medium rotary hammers, small and medium holes, and limited chiselling.
SDS MaxUsually an 18 mm nominal shank system for heavy rotary hammers, large drill bits, core bits, and intensive demolition.
Interchangeable chuckSome rotary hammers allow the complete SDS unit to be quickly replaced with a three-jaw keyless chuck for wood or metal drilling.
SDS adapterAn adapter with an SDS shank can carry a conventional chuck, but it adds length and is generally not intended for full pneumatic hammer operation.
