Is there any way that I can calibrate/check my torque wrench? I often read of these tools being out of adjustment but have never read of the cure. Any help please.
Regards
Derek
Regards
Derek
Torque wrench calibration
- Thread starter DerekBrad
- Start date
Why not just Google "torque wrench calibration" it only returns a couple of thousand suggestions or ask the garage where you get your car serviced where they get theirs done, if they don't know I suggest you find another garage for your car 
The cost of checking & re-calibrating a cheap torque wrench would be more than replacing it with another cheap new one.
Steve W
Steve W
But how would you know the new one was accurate?, I've never seen a calibration certificate supplied with a cheap torque wrench.steve w77 said:
The manually adjustable torque wrenches commonly used by tyre fitters and the garage trade are notoriously difficult to calibrate. Firstly there the repeatability of setting the desired value, and secondly the wrenches in typical use are so open to abuse that a calibration certificate cannot be trusted except at the time it is issued.
As Nick states unless the wrench is supplied with a proper certificate of conformancy, you can't have any real confidence that the wrench will be any better than an old one.
Even with the inherent errors of the absolute setting, it is likley to be closer to the desired value than attempting to do it by hand and guess work, and definately more consistent until the wrench is re adjusted to a differnt setting.
In aerospace work, either dedicated preset calibrated wrenches are used, or the manual setting is proven on a test guage before being used on the job in hand.
As Nick states unless the wrench is supplied with a proper certificate of conformancy, you can't have any real confidence that the wrench will be any better than an old one.
Even with the inherent errors of the absolute setting, it is likley to be closer to the desired value than attempting to do it by hand and guess work, and definately more consistent until the wrench is re adjusted to a differnt setting.
In aerospace work, either dedicated preset calibrated wrenches are used, or the manual setting is proven on a test guage before being used on the job in hand.
I have a torque wrench which I bought in 1964 and have checked it against my sons torque wrench which he bought from halfords a few months ago and the readings are the same
allan
allan
i used to do deliveries for comech in derby they do calibration , you could call them and ask the question, 01332 867700
In theory it's fairly easy. Clamp a socket in a vice with the hole horizontal, insert torque wrench so handle is horizontal. Hang suitable cord round the handle at a convenient number of feet from the centreline of the drive shaft. Add dead weights to the string until you have the same or more as the setting and the wrench should click over.
The practical problem is that with a torque wrench handle say 2 ft long ( as described above) you will need to hang 40lb wieght to get to 80ft-lb and will probably find it quite difficult to assemble this sort of weight in a reasonable size. I've picked 80 ft-lb as a typical figure but many wheel torquess are way above this.
Another way would be to pull on the handles with a spring balance but then again you would need to know the calibration of the spring balance and be fairly strong.
Please mind your toes and other vital parts if you try this at home.
The practical problem is that with a torque wrench handle say 2 ft long ( as described above) you will need to hang 40lb wieght to get to 80ft-lb and will probably find it quite difficult to assemble this sort of weight in a reasonable size. I've picked 80 ft-lb as a typical figure but many wheel torquess are way above this.
Another way would be to pull on the handles with a spring balance but then again you would need to know the calibration of the spring balance and be fairly strong.
Please mind your toes and other vital parts if you try this at home.
I have used a permutation on Ray's technique but using a bucket suspended from a four foot aluminium tube over the spanners shaft. Then just topped up with water till the wrench "snapped", with the quanity of water needed and distance along the lever arm known the torque is determined. Sorry for the purist but I cant remember correcting for the tube weight but next time even that is an easy calc.
A very long while ago I made a bending bar wrench myself and devised this techinque to calibrate that, times were hard in those late 1950s days.
A very long while ago I made a bending bar wrench myself and devised this techinque to calibrate that, times were hard in those late 1950s days.
Exactly, I was a commercial vehicle fitter and later I owned my own workshop and I do not see the need for anyone other than a professional to actually own a torque wrench. As far as wheel bolts are concerned, tight is tight. I have never come across a wheel that has come loose unless it was not fitted properly in the first place, or it has been tampered with.
Steve W
Steve W
Hi Steve W.
In part I agree with you,I too was a fitter on Coaches and due to lack of knowledge I have seen some nasty things happen to over tightened wheel nuts and bolts where the they been stretched .
I believe as caravanners we should all either have a torque spanner or have them checked on a regular basis especially in this day an age of alloy wheels. at leats each nut or bolt will be exactly the same .
Sir Roger
In part I agree with you,I too was a fitter on Coaches and due to lack of knowledge I have seen some nasty things happen to over tightened wheel nuts and bolts where the they been stretched .
I believe as caravanners we should all either have a torque spanner or have them checked on a regular basis especially in this day an age of alloy wheels. at leats each nut or bolt will be exactly the same .
Sir Roger
Very sorry I can't agree with Steve. It is all too easy to overtighten and stretch bolts or studs and there is no outward evidence until suddenly there is no wheel there. I days gone by when the components concerend were probably all of fairly similar material e.g. stell this was less of a problem. I served an apprenticeship in the aircraft industry in the 1950's and the importance of correct torquing was well known even then.
Purely as a matter of interest.I have an old beam type wrench,the one with a long needle that moves across a fixed scale as you tighten a bolt,do these need calibrating ? I bought it s/hand about 20 years ago for about a fiver.
I also have a cheap modern type wrench I bought from screwfix that is only used for the wheels on the car & caravan.They both seem to read more or less the same
I also have a cheap modern type wrench I bought from screwfix that is only used for the wheels on the car & caravan.They both seem to read more or less the same
Hi TD42
I used one of those beam torque wrenches for years infact I still have mine hanging in the shed.
I found that if you kept the needle set in the centre position it was never far out and again each whell nut would be near enough the same .
Again as I said in my previous post I saw some nasty
things happen through stretched bolts when I worked on the coaches all because a torque wrench had never been used.
Sir Roger
I used one of those beam torque wrenches for years infact I still have mine hanging in the shed.
I found that if you kept the needle set in the centre position it was never far out and again each whell nut would be near enough the same .
Again as I said in my previous post I saw some nasty
things happen through stretched bolts when I worked on the coaches all because a torque wrench had never been used.
Sir Roger
You can't seriously compare aircraft with caravan and it is almost impossible to stretch a wheel bolt using a spider wrench unless you use 6ft of scaffolding pipe to extend it.
Steve W
Steve W
Steve
Read this old thread
http://www.practicalcaravan.com/forum/general/a-very-wet-dustydog?page=1
The wheel nuts on both car and caravan are now checked before each trip . The torque wrench lies in the boot.
I've checked it's performance against a friend's wrench and they seem to click at the same setting so I must assume it's still reasonably accurate.
Read this old thread
http://www.practicalcaravan.com/forum/general/a-very-wet-dustydog?page=1
The wheel nuts on both car and caravan are now checked before each trip . The torque wrench lies in the boot.
I've checked it's performance against a friend's wrench and they seem to click at the same setting so I must assume it's still reasonably accurate.
TD42 said:
If it was ever right and the pointer zeros "off load" then it does not need recalibrating as the bars elasticity characteristics will not change with time.
The presumption here though is was it ever "right" and right throughout its scale. These type are my favourite as they give a better "feel" and awareness of the progression to the reqired torque plus of course they dont require presetting. I made my own for a specific job.
Checking it is not very difficult and even if it’s out enough to worry you then you can mark up a new scale on masking tape over the existing one. If the pointer does not exactly zero then you can bend that "back" but then must recheck the calibration.
If its only for one job, your caravan wheel bolts, then its temping to check that specific value and mark the scale there with a flash of paint, then there is no mucking about needed when it is used.
The motor trade doesn't seem to bother much with torque wrenches, let alone calibrated ones - most of the time they'll just use an air gun and never alter it's settings for weeks on end, if at all. I'm also aware of a franchised car dealer that routinely re-uses stretch bolts despite every model of the brand they sell using stretch bolts in obvious places.
As far as cars go, those of us who use cheap, uncalibrated, torque wrenches from Argos, Draper, etc are at least way ahead of the trade on this issue.
I never got to see the caravan workshop during the 2 warranty services my caravan had - but subsequently I've watched a mobile caravan engineer (not ACW approved) and he used a professional torque wrench, although I've no idea if it was calibrated.
Is lack of calibration really an issue? - or is lack of using any form of torque wrench a much bigger problem? - I do mean for cars and caravans, not specialised industries.
As far as cars go, those of us who use cheap, uncalibrated, torque wrenches from Argos, Draper, etc are at least way ahead of the trade on this issue.
I never got to see the caravan workshop during the 2 warranty services my caravan had - but subsequently I've watched a mobile caravan engineer (not ACW approved) and he used a professional torque wrench, although I've no idea if it was calibrated.
Is lack of calibration really an issue? - or is lack of using any form of torque wrench a much bigger problem? - I do mean for cars and caravans, not specialised industries.
Borrow and secure the handle of a beam type in a vice, fit a suitable socket, attach the other torque wrench, and wind it up!
BTW anyone see the Caravan Channel the other day, where a mechanic showed us how to remove a wheel brake / drum? Couple of points, I would like to think that I did not see him use a torque wrench to undo a nut, a definite no no and secondly no mention of brake adjustment afterwards.
Given my age I might have fallen asleep though
BTW anyone see the Caravan Channel the other day, where a mechanic showed us how to remove a wheel brake / drum? Couple of points, I would like to think that I did not see him use a torque wrench to undo a nut, a definite no no and secondly no mention of brake adjustment afterwards.
Given my age I might have fallen asleep though
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