Torque Wrench Calibrations

[Ashley Burton]

It crossed my mind today, Is it worth getting my torque wrench calibrated? Had it for a good few years & it gets used quite a bit.

Does anyone else bother?

Many Thanks

 

[DaveB]

If you have access to some weights then it is a worthwhile exercise to do it yourself.

 

[Ashley Burton]

If you have access to some weights then it is a worthwhile exercise to do it yourself.

As much as I love DIY I would prefer it done by a professional

 

[addjunkie]

I had mine done recently but only because I had "access" to a man who could. First time in 15 years

 

[Ed ke6bnl]

Just a thought, could you compare it to one of those digital units like Harbor Freight sell that goes on a ratched workd to check it. Do not know anything about that particular unit but I would guess it might be accurate.

 

[Parm]

Do you have a critical application ?

Or is it just a nice to have ?

 

[Robotstar5]

I took my 2 late 70's Norbar wrenches into work and tested them on the certified calibration rig, they were both still near enough across the range not to worry about

 

[DaveB]

Just a thought, could you compare it to one of those digital units like Harbor Freight sell that goes on a ratched workd to check it. Do not know anything about that particular unit but I would guess it might be accurate.

You have to have a reference that you know is accurate and be able to compare the two when loading them both at the same time.

If you calibrate with weights then your reference is earths gravity which does not fluctuate enough to affect the accuracy for most day to day purposes.

As much as I love DIY I would prefer it done by a professional

A calibration is likely to cost you £75, and it is only a set of measurements of your wrench against a standard. If you wrench is wrong and needs servicing that will have to be done by a servicing specialist ( not the calibration lab ).
Torque wrenches of the "click" type normally set to an accuracy to between 4% and 10%.
The repeatability of the action at any set value is also important, if the repeatability once set to a value is worse than the accuracy then the wrench is worn out.
Calibration as a job is mostly record keeping and being a pedant, I quite enjoy it some days

 

[Welderpaul]

We have a couple of Norbar 3/4" torque wrenches - we get them calibrated every 12 months and test 10% of critical fixings after erection. They are kept in a cupboard and not rolling round in the back of a van - as long as they are treated with care they won't loose calibration.

 

[waddycall]

Why not just check it at a couple of settings with weights just to satisfy your curiosity.

 

[Ruffian]

Every 12 months all 5 of mine get checked,
Guy does it for £15 a torque wrench (and will reset if easy and nessasary)

Not worth the risk in my eyes,
If a wheel comes off or similar i have certification to prove they all work near enough 100%

 

[Johnseat]

We have ours done every six months by oak range, something to do with the works insurance.

 

[MCKDAVID]

As above, in my view, if you're in an industry / service where that level of precision is required, then calibrate as necessary - that would no doubt be part of the company operating procedures / applicable standards somewhere. For "non professional" use, i.e. nipping up / checking the bolts on the occasional project at home, I doubt they'd be far enough out to worry. That said looking at the condition of the wrench itself will probably give you some indication of it's accuracy, if it's clean and well kept or battered to hell and back... not that would be a cast in stone argument, but...

Critical or not, you'll know your application best...

 

[Wallace]

Ashley, do you unwind your torque wrench after use? Keeps them in tolerance longer if the spring is not left compressed.

 

[Ashley Burton]

Ashley, do you unwind your torque wrench after use? Keeps them in tolerance longer if the spring is not left compressed.

Yeah always unwind, But the torque wrench is over 5 years old now & had plenty of use!

 

[Bill Edwards]

Well storing it correctly should make a huge difference. However, if it's seen a lot of action then the only correct answer has to be get it checked, if it's a good quality one it's probably still ok but it's impossible to guarantee that.

My Snap On dealer has a device which measures the accuracy of a torque wrench which is handy if you deal with them, I've taken a wrench on and checked it in a couple of minutes so if you deal with one that may be an option.

For most applications torque isn't super critical, but giving the same figure each time is crucial for things like head bolts. But with that said, I do use a SO digital torque wrench for almost everything now which I know can only be correct (stops working when it's more than a couple of % out) so I'm always correct.
It's all down to what you do and what's at stake.

 

[brightspark]

i used to do jobs at cumins diesel . never gave it a thought I could have tested my ones there every day before use they tested there wrenches they repaired and rebuilt massive 12 cylinder engines out of drag lines in quarries etc 11 grand for a reground crank on one

 

[wristpin]

So the test shows one to be unacceptably inaccurate - what then, how is it adjusted or calibrated? My big old Britool ones are just a spring, a plunger and a rocking release trigger. No sign of any way to adjust the setting other than to shim the spring perhaps.

 

[Bill Edwards]

Some have a screw, others I think have to be taken apart.

 

[Farside]

Yeah always unwind, But the torque wrench is over 5 years old now & had plenty of use!

My 1/2" TR is 30 years old and had lots of use back then. Any time I've thought about it, and checked it against Mother Nature, it's been fine.
I've never left it tightened up, though. That's not to say someone else didn't, but it wasn't left for long enough to cause a problem.