Hand ToolsDriver
Combination Wrench
A single forged bar with an open jaw at one end and a ring at the other, sized across flats. The tool that turns a hexagon head when there is no room for a socket.
What it does
- Turning hexagon head bolts and nuts
- Holding one side of a bolted joint while the other is driven
- Working in a confined space that rules out a socket
Fasteners it fits12 standards specify external hexagon
All standardsMatched on the drive form recorded against each standard, not on the tool's own claims — so this list changes when the fastener data changes, not when this paragraph does.
What to look forthe judgement calls, before the spec sheet
- Size is across flats, matching the bolt head and the nut. Metric and unified sizes are close enough to nearly interchange, which is how heads get rounded.
- The ring end takes the load; the open end is for access. Where the joint is tight, drive with the ring and use the open end to react.
- A ratcheting wrench is faster but has a mechanism in the ring that will not take the same torque as a solid one.
Misuse and safetythe ways this tool causes rework
- An open-end jaw only contacts two corners of a hexagon. It is the end that rounds fasteners, and it should not be the end you pull hardest on.
- Wrench lengths are matched to bolt sizes. A pipe on the handle multiplies your input past what the fastener or the wrench was made for, and something gives.
Projects that call for itand what it is doing on each one
All projectsFrequently asked questions
Can I use a wrench to tighten to a specified torque?
Not to a known figure. It will tighten the joint, but the number on the drawing needs a torque wrench. Snug with the wrench, then finish to the figure.
Why buy a set rather than individual wrenches?
Because a joint nearly always needs two sizes — the bolt and the nut on the same fastener are often different. A set also means the correct size is available rather than nearly correct.