Hex Key, Long Arm, Metric Sizes
What Is a Long Arm Hex Key?
A long arm hex key is an L-shaped hex wrench where the short leg of the L is lengthened compared to a standard hex key, giving the driving end better access into recessed bores, deep counterbores, and tight assemblies. Turning the tool from the long end also provides more leverage, which helps when breaking loose a tight or seized socket head fastener.
Like standard hex keys, long arm keys are ground hex on both ends and sized to fit standard metric socket head cap screws, socket set screws, and other hex-drive fasteners. They are a common choice in machine assembly and maintenance where fasteners sit below the surface or where extra torque is needed without a torque wrench.
Key Features and Benefits
- Extended Short Leg: reaches recessed and counterbored fastener heads that a standard hex key can't access.
- Increased Leverage: the longer arm gives more mechanical advantage for breaking loose tight fasteners.
- Hex Drive on Both Ends: either end can be used as the driving end depending on clearance.
- Full Metric Size Range: matches standard metric socket head fasteners.
- Hardened Steel Construction: built to resist twisting and rounding under torque.
Materials and Finishes
- S2 Tool Steel: hardened for durability under repeated torque loading.
- Black Oxide Finish: low glare, corrosion resistant finish suited to shop and field use.
Standards Compliance
- ISO 2936, Hexagon socket screw keys, dimensions
- DIN 911, Hexagon socket screw keys
- ASME/ANSI B18.3, Reference dimensions for hex socket head fasteners and keys
Size Range and Availability
Available in a full metric hex key size range, sold individually or as multi size sets.
Related Categories and Products
Frequently Asked Questions (FAQs)
1. What is the difference between a long arm and a short arm hex key?
A long arm hex key has an extended short leg, giving it better reach into recessed fasteners and more leverage when turned from the long end. A short arm hex key has a shorter overall profile suited to tight clearance spaces.
2. When should I use a long arm hex key instead of a short arm key?
Use a long arm hex key when the fastener sits in a deep counterbore or recess, or when extra leverage is needed to break loose a tight fastener.
3. Do long arm hex keys fit the same fasteners as short arm hex keys?
Yes, both styles are sized to the same standard metric hex socket dimensions and fit the same fasteners.
4. Can either end of a long arm hex key be used to drive a fastener?
Yes, both ends are ground hex, so you can choose whichever end offers better clearance for the application.
5. Are long arm hex keys available as sets?
Yes, they are sold individually and in multi size sets covering a full metric range.
6. What material are long arm hex keys made from?
They're made from hardened S2 tool steel with a black oxide finish for wear resistance and corrosion protection.
