How to use an open ended spanner without rounding the nut
Updated: 23 October 2026
The nut is already shining on two corners, and one more careless pull will turn the hex into a circle. How to use an open ended spanner comes down to three checks: the jaw is the right size, it sits square, and you stop when it starts to slip. The [open-ended spanner comparison](/hub/hand-tools/open-ended-spanner) holds the listings, as read on 22 October 2026. Peter F., DIY and tools editor, used Haynes, CAR magazine, Rapid and the HSE note on work equipment. We did not run a torque test. A qualifying purchase can earn a commission at no extra cost to you.
The nut is already shining on two corners, and one more careless pull will turn the hex into a circle.
The nut is already shining on two corners, and one more careless pull will turn the hex into a circle. How to use an open ended spanner comes down to three checks: the jaw is the right size, it sits square, and you stop when it starts to slip. The open-ended spanner comparison holds the listings, as read on 22 October 2026. Peter F., DIY and tools editor, used Haynes, CAR magazine, Rapid and the HSE note on work equipment. We did not run a torque test. A qualifying purchase can earn a commission at no extra cost to you.
Our top picks
| Badge | Product | Head angle | Head | Named steel | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Draper Draper 24 mm single open-end | 15° stated | Single, raised collar | Chrome vanadium | 6.7 | about £5.00 | View offer |
 BGS BGS 12-piece double open-end set | n/a | Standard open end | Chrome vanadium | 7.5 | about £19.09 | View offer | |
| Best value |  Hilka Hilka 8-piece open-ended set | n/a | Open end | Chrome vanadium | 6.7 | about £11.63 | View offer |
On this page
Put the right jaw on square
An open jaw bears on two flats. Haynes’ UK tool note says that limited contact is why the spanner can slip, mark the fastener and catch your knuckles, and why a ring is the better first choice when it will fit. If you see daylight down one side, or the jaw rocks, it is the wrong size. Seat the opening so both faces touch, then pull the handle toward you. If you have to push, keep your hand out of the line of a slip. If the jaw clicks onto the corners, stop. A missing size is the buying guide.
Use the 15° flip
Many open-ends are cut at about 15°. Rapid describes that angle as a way to reposition: a short swing, then turn the spanner over, and the same jaw meets the next flats. CAR magazine’s UK guide says a plain open jaw may need about 60° before the same bite returns. A 12-point ring needs about 30°. The flip shortens that wait. If the listing prints no angle, do not assume a 15° head. The BGS and Hilka files do not print one. The Draper 24 mm single does.
When the open end is the wrong tool
Stop when the jaw starts to slip, when the nut is rusty, or when a torque is specified and you cannot set it. Haynes’ rule is to use a ring where you can. That choice is on open-ended versus combination. A brake or fuel pipe needs a flare-nut spanner. If the normal head will not enter, the buying question is on thin open-ended spanners. A nut you can already turn, on a bolt you can see, is the work an open end is for.
Do not lengthen it
Do not slide a tube, a pole or a second spanner over the handle. Extra length multiplies the force on two flats and on the shank. On the Draper 24 mm single, one UK text says the spanner snapped. Another describes a pole used on that single. At work, PUWER 1998 makes a spanner work equipment. HSE asks that it be suitable and maintained. A pipe on the handle fails that. The rule is the same at home: right jaw, square seat, no tube.
Common questions
Which way should the jaw face when I pull?
Square to the flats, with both faces of the opening touching, and with the handle in line with the pull. Draw the handle toward you when the nut allows. If you must push, keep the jaw seated and your knuckles clear, because Haynes notes that an open end can slip and hit you. The thread sets clockwise or anti-clockwise.
What does the 15° offset change if I flip the spanner?
It gives you a new bite after a short swing. You pull, turn the spanner over, seat it again, and pull. CAR’s guide says a plain open jaw may need about 60° before the same bite returns, against about 30° for a 12-point ring. The flip is that geometry. It does not tighten a loose fit. If your spanner’s listing never printed an angle, you may not have the offset, and you plan for the longer swing instead.
Why did the spanner slip and round the nut?
Usually because the jaw was the wrong size, was not seated, or was asked to break a nut that needed a ring. Two flats cannot hold like a ring once the corners soften. A rocked jaw, a size that only looks close, or a cheater tube all show up as a slip and then a round. Stop at the first click. If the stamp and the flats disagree, measure. Do not keep pulling because the last turn almost moved.
Can I put a tube on the handle?
No. A tube, a pole or another spanner over the shank overloads the jaw and the handle. One UK review of a 24 mm single reports a snap. A different review on that listing describes a pole. Those stay two separate reports, not a statistic and not a licence to copy either of them. If the nut will not move with a fair pull, use a ring, a socket, or penetrating oil and time. Do not add length.
When should I stop and fetch a ring or a socket?
When the nut is tight, rusty, or already starting to slip, and whenever a torque is specified. Haynes’ rule is to prefer a ring where it will go on. Use a socket for the same reason if access from the end is open. An open jaw remains the tool for a nut on a long stud, or for holding one size while you turn another.
Is a thin spanner used the same way?
The seat is the same: right size, square, pull in line, stop when it slips. The load is not the same. A stated 3 mm head is for a gap, not for breaking a fastener free. If the ordinary head will not enter, read the thin-spanner page before you lean on the slim one. A flare-nut spanner, not a thin open jaw, is the tool for a brake-pipe nut.
Related pages
Sources
Sources from the research digest, last checked on 22 October 2026.
- HSE, PUWER overview (retrieved 22.10.2026)
- ISO 10102:2018, assembly tools for screws and nuts (retrieved 22.10.2026)
- BSI, BS ISO 1711-1:2019 hand-operated wrenches and sockets (retrieved 22.10.2026)
- TED, spanners, citing ISO 3318:2016 (retrieved 22.10.2026)
- Haynes UK, car maintenance tools (retrieved 22.10.2026)
- Faithfull compression fitting spanner, 15 mm and 22 mm (retrieved 22.10.2026)
- Monument 15 mm and 22 mm compression fitting spanners (retrieved 22.10.2026)
- Teng Tools 6211, trade double open-end set (retrieved 22.10.2026)