Torque Wrench calibration.

I’ve got a couple of torque wrenches (a small one for the lower torque ranges and a big one for the upper ranges).I go on feel when tightening certain bolts - but for important stuff like axle nuts and sump plug bolts I like to use me torque wrench - as it gives me piece of mind to know that the bolt is on at the right torque and there is no danger of cracking the sump with an over tightened drain plug bolt - or the drain bolt falling out and covering me rear tyre with oil, at 90 mph. . . :w00t:

However - all of this is cobblers if the torque wrench is not calibrated properly - and i’ve gone through probably a couple of thousand clicks on each wrench after a few years of owning them - so I want to check that they are applying the correct amount of torque by getting them calibrated.

Anyone know of the kind of place that does this (if they exist).

Thanks in advance. :wink:

Before seeing if this service does exist/finding out what it costs … could it be as simple as borrowing a wrench from a friend - tightening a nut to a specific level with yours - then using his wrench to see if it is too much/too little/correct …?

Highly unlikely that two different makes/models/ages of wrench will be out by the same amount?

Just an idea :slight_smile:

Nice idea! :smiley:

I’ve used a method similar to this to check my big Teng torque wrench :

Thanks G!

Unfortunately I’m shite at maths - probably looks quite straightforward to you engineering types - but I got confused halfway through reading it! ;):smiley:

Confused? I got bored and confused. Typical American “too many words”, poor English construction.

The basics are that you clamp the sqare drive in a vice. Level the wrench. Set the wrench to a known setting of your choice. Hang an equivalent weight on it and see if it clicks over or if you need more or less weight.

Example (In old ft/lb). Do the clamping, set it to 10 ft/lb and hang a 10 lb weight on the wrench 1 foot from the centre of the square drive.

If it clicks before you’ve you’ve completely let go of the weight it over reads/under tightens. (Safe for most work) If you have to add more weight, it under reads/over tightens. (Can be critical on aluminium castings.)

O.K. so far. Good.

Now stop fretting. If the wrenches are half decent quality, they are stupid reliable. I checked my 30+ year old Norbar a few years back and it was pretty much spot on despite being used extensively when I was young and enjoyed this dirty machinery stuff.

I used that wrench to check a new, cheap, low reading one last year and that was pretty much spot on the Norbar readings where they overlapped.

But if you don’t take the tension off them, they can go out of calibration pretty damned quickly
I don’t actually use mine much - just for things like engine mountings and stuff - I rely on years of experience stripping threads to tell me how tight :slight_smile:

Thanks Oldguy for translating the D.I.Y. calibration procedure - i’ll give it a go - and thanks Gurniman for letting us know about it. ;):slight_smile: