Calibration on torque wrench ????? How often

[Richard Simpson Mark II]

On wheel nuts/studs for trucks and buses, two figures are sometimes quoted...'dry' and 'lubricated'.

Best practice should be to lubricate and use the lubricated figure...it will give a more consistent tension than dry because there is less (unpredictable) static friction...if that makes sense...

[Mikekitts81]

On wheel nuts/studs for trucks and buses, two figures are sometimes quoted...'dry' and 'lubricated'.

Best practice should be to lubricate and use the lubricated figure...it will give a more consistent tension than dry because there is less (unpredictable) static friction...if that makes sense...

But then if they don't lubricate it from the factory aren't you then putting more torque on the bolt and thread that there should be as lubrication want have the same static friction meaning it would over tighten before feeling tight due to less friction ...

[Richard Simpson Mark II]

Well, the manual or whatever should make it plain. But yes, the lubricated figure will always be lower to achieve the same clamping force.

For instance, doing the head-bolts on a Pugrat engine, even the Haynes manual says to 'lubricate liberally', and then gives figures for progressive tightening, finishing off with a final half-turn (or whatever) bolt-stretcher. If you attempted the task with dry bolts, you'd have to go to a far higher figure to get the same clamp/stretch force on the assembly.

[Craig-SM]

I have a 3/8 and 1/2 inch Halfords torque wrenches. I’ve always released the tension after use and stored them back in their tubes. Had them both calibrated last year. Despite them being around 10 years old and had a fair bit of use the 3/8 was still within spec and the 1/2 was only just out which surprised me and my mate who calibrated them who is a bit of a Snap On fan boy.

[Grim Reaper]

I bought a digital torque adapter and used this to test how accurate my Norbar and Lidl mechanical torque wrenches were.
All within spec, but if not the Norbar ones can be adjusted with an allen key. Not sure about the Lidl one but it came with a certificate of calibration so could have returned it if it was out.

[threepot]

A friend recently used his Norbar to slacken the rear axle bolt on his bike,and guess what!!

[Richard Simpson Mark II]

He found out it's a measuring instrument, not a tool

[Hugh]

Greetings again,

I did have a lecture note that I had produced about 30 years ago on this subject but could not find it when I sent in my previous comments. Probably superseded now anyway

Whilst looking for something else on the internet my mind wandered, as it often does, and I came back to this question

Here are another couple of websites to take a look at for explanations and information if you are still interested;

https://www.norbar.com/en-gb/News-Event ... alibration

http://www.instructables.com/id/Fixing- ... que-Wrenc/

Remembered what I was looking for so bye for now

TTFN

Hugh.