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Accuracy of torque wrenches?
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Accuracy of torque wrenches?
Does anyone know how accurate torque wrenches are?
I have a 1/2" SWG torque wrench that I'm starting to use more and wonder just how accurate it is. I have no intention of getting it calibrated due to the cost factor though.
I have a 1/2" SWG torque wrench that I'm starting to use more and wonder just how accurate it is. I have no intention of getting it calibrated due to the cost factor though.
Re: Accuracy of torque wrenches?
For the price of them, theyed want to be as accurate as possible.
MrsForby wrote: Oh I desperately truly love the taco.
Re: Accuracy of torque wrenches?
we get ours calibrated at work and was speaking to the guy who was calibrating them and he said stay away from some of the cheaper ones as they are not the accurate and some he cannot get back into spec (including the new ones)
home brew cooling in progress
Re: Accuracy of torque wrenches?
Yep, comes down to quality of torque wrench. We just bought some at work for $450 each, they are 1/4" drive and are permanently set to 1Nm. They are accurate to about 3% going by the calibration certificates. Others are meant to be about 6% I think.
Re: Accuracy of torque wrenches?
unless your the one thats taken it out of the box with the calibration certificate, you dont know whats been done with it
xxxx wrote:
Re: Accuracy of torque wrenches?
One of those new ones I was talking about got dropped from 20m up in the scissor lift, first time it got used. When they lowered the lift there was a loud bang. Found the torque wrench in the base of the scissor, not too bad but the socket off it had been crushed by the scissor arms. May need a new calibration certificate.Ice wrote:unless your the one thats taken it out of the box with the calibration certificate, you dont know whats been done with it
Re: Accuracy of torque wrenches?
I've picked old snap on torque wrench, made in 1986 i think, it came with original box and instructons. It's got the dial in middle of it which i'd never seen before, i don't really need it calabrated, but i'd like to see how accurate it is. Is there an easy way to do this?
Braden Tagg of XRO Racing is scum and not to be dealt with. See here http://www.outerlimits4x4.com/viewtopic.php?f=10&t=223295
bj73 build up thread http://www.outerlimits4x4.com/ftopic168809.php
bj73 build up thread http://www.outerlimits4x4.com/ftopic168809.php
Re: Accuracy of torque wrenches?
Send it back to Snap-on. If it is out of calibration they should supply a new one as a part of their lifetime guarantee. Check with them first, but they are usually pretty good.sprungupcruiser wrote:I've picked old snap on torque wrench, made in 1986 i think, it came with original box and instructons. It's got the dial in middle of it which i'd never seen before, i don't really need it calabrated, but i'd like to see how accurate it is. Is there an easy way to do this?
George Carlin, an American Comedian said; "Think of how stupid the average person is, and realise that half of them are stupider than that".
Re: Accuracy of torque wrenches?
Torque = Force x radius
Force = mass x G (gravitational constant = 9.81 or thereabouts)
Find largish wheel (27" bicycle wheel?) , mount solidly to axle. Mount axle in "frictionless" bearings, so that axle & wheel spins freely.
Run rope around wheel, and tie to weight on ground.
Use torque wrench to turn axle to lift weight. Determine the setting/reading at which torque wrench can no longer lift weight.
Torque = mass (in kg) x radius (in metres) x 9.81
That's the theory. Test it for me?
Force = mass x G (gravitational constant = 9.81 or thereabouts)
Find largish wheel (27" bicycle wheel?) , mount solidly to axle. Mount axle in "frictionless" bearings, so that axle & wheel spins freely.
Run rope around wheel, and tie to weight on ground.
Use torque wrench to turn axle to lift weight. Determine the setting/reading at which torque wrench can no longer lift weight.
Torque = mass (in kg) x radius (in metres) x 9.81
That's the theory. Test it for me?
Re: Accuracy of torque wrenches?
DUDELUX wrote:For the price of them, theyed want to be as accurate as possible.
SWG isnt an expensive torque wrench.
if in doubt put a drop or 2 of 243 on the thread. bolts have a torque allowance for the torque wrench, not the bolt.
turbos are nice but i'd rather be blown
Re: Accuracy of torque wrenches?
Huh?chunderlicious wrote:if in doubt put a drop or 2 of 243 on the thread. bolts have a torque allowance for the torque wrench, not the bolt.
To quote our (in)famous ex-pat, "Please explain?"
Re: Accuracy of torque wrenches?
Thats a good idea, might be $40 well spent. hahaDAMKIA wrote:Send it back to Snap-on. If it is out of calibration they should supply a new one as a part of their lifetime guarantee. Check with them first, but they are usually pretty good.sprungupcruiser wrote:I've picked old snap on torque wrench, made in 1986 i think, it came with original box and instructons. It's got the dial in middle of it which i'd never seen before, i don't really need it calabrated, but i'd like to see how accurate it is. Is there an easy way to do this?
-Scott- wrote:Torque = Force x radius
Force = mass x G (gravitational constant = 9.81 or thereabouts)
Find largish wheel (27" bicycle wheel?) , mount solidly to axle. Mount axle in "frictionless" bearings, so that axle & wheel spins freely.
Run rope around wheel, and tie to weight on ground.
Use torque wrench to turn axle to lift weight. Determine the setting/reading at which torque wrench can no longer lift weight.
Torque = mass (in kg) x radius (in metres) x 9.81
That's the theory. Test it for me?
Stuff that, I like the first idea better. You lost me torque.
Braden Tagg of XRO Racing is scum and not to be dealt with. See here http://www.outerlimits4x4.com/viewtopic.php?f=10&t=223295
bj73 build up thread http://www.outerlimits4x4.com/ftopic168809.php
bj73 build up thread http://www.outerlimits4x4.com/ftopic168809.php
Re: Accuracy of torque wrenches?
We've had ours recalibrated at work in the last few weeks, I'll check the invoice too see how much we paid for interests sake.
Re: Accuracy of torque wrenches?
i got a headache now better get another beer-Scott- wrote:Torque = Force x radius
Force = mass x G (gravitational constant = 9.81 or thereabouts)
Find largish wheel (27" bicycle wheel?) , mount solidly to axle. Mount axle in "frictionless" bearings, so that axle & wheel spins freely.
Run rope around wheel, and tie to weight on ground.
Use torque wrench to turn axle to lift weight. Determine the setting/reading at which torque wrench can no longer lift weight.
Torque = mass (in kg) x radius (in metres) x 9.81
That's the theory. Test it for me?
lol
cheers mick
Re: Accuracy of torque wrenches?
Find someone with a nice new calibrated one, do up one bolt with yours and one bolt with theirs. Then see if either one will tighten the other bolt at all. Repeat this a few times to get consistent results. Should give a rough indication of how accurate your wrench is.sprungupcruiser wrote:I've picked old snap on torque wrench, made in 1986 i think, it came with original box and instructons. It's got the dial in middle of it which i'd never seen before, i don't really need it calabrated, but i'd like to see how accurate it is. Is there an easy way to do this?
Re: Accuracy of torque wrenches?
can you not just get bolt, put it in a vice, so it will not move.
fit the torque wrench to the bolt head.
measure out a nice neat number from the center of the head to somewhere on the handle (further out the better for greater accuracy). attache a fish type set of hanging scales to this point on the handle.
lets use the example of 400mm as mine has a 400mm handle - 0.4m
get a fish weight, say 5kg.
f=ma
f=5 x 9.8
f=49N
T (torque) = md Where d is the perpendicular distance from the point of rotation. in this example 0.4meters
T = 49 x .4
= 20Nm
or with 10kg pull? 40Nm
this might be too low for your torque wrench to test. but the idea is that you set it to 20Nm and see it it clicks when you pull on the fish scale and it reads 5kg.
Should give you a fairly good idea of its accuracy, i.e if it clicks at 4.5kg its 10% out. if it clicks at 4.9 or 5.1kgt then its 2% out.
fit the torque wrench to the bolt head.
measure out a nice neat number from the center of the head to somewhere on the handle (further out the better for greater accuracy). attache a fish type set of hanging scales to this point on the handle.
lets use the example of 400mm as mine has a 400mm handle - 0.4m
get a fish weight, say 5kg.
f=ma
f=5 x 9.8
f=49N
T (torque) = md Where d is the perpendicular distance from the point of rotation. in this example 0.4meters
T = 49 x .4
= 20Nm
or with 10kg pull? 40Nm
this might be too low for your torque wrench to test. but the idea is that you set it to 20Nm and see it it clicks when you pull on the fish scale and it reads 5kg.
Should give you a fairly good idea of its accuracy, i.e if it clicks at 4.5kg its 10% out. if it clicks at 4.9 or 5.1kgt then its 2% out.
*there's a rock, drive over it :) there's a bigger rock, drive over it :twisted: there's an even bigger rock, oops broke it :oops: Upgrade broken bit :bad-words:
Goto *
Goto *
Re: Accuracy of torque wrenches?
Get a callibrated torque wrench and a bit of hex bar, put your torque wrench with socket on it onto one side of the hex bar and do the same on the other side of the hex bar with the callibrated torque wrench,
set both to 100 N.m.
Pull both together then match your setting to the callibrated one at 100 N.m so yours goes off when it does, the difference of yours to the callibrated one is the percent difference.
I just got mine checked at a local engine reco shop and found that my 10 yr old snap on was 4% high, the guy tested for free and only took 2 mins
set both to 100 N.m.
Pull both together then match your setting to the callibrated one at 100 N.m so yours goes off when it does, the difference of yours to the callibrated one is the percent difference.
I just got mine checked at a local engine reco shop and found that my 10 yr old snap on was 4% high, the guy tested for free and only took 2 mins
Re: Accuracy of torque wrenches?
If you are going to check the calibration of your torque wrench, don't just check it in the lower range because it may not be all that consistent across the range. When I was doing calibration of flight line tension wrenches they were tested every month and at every 10 ft lbs right across the range and some can be much less accurate down low and up high. I have 4 tension wrenches (all different ranges) and only use one that is most suited for the tension being applied, ie. don't use a 200 ft lb wrench if only tensioning to 25 ft lbs etc. Yours may be accurate in that instance, but many aren't.
Re: Accuracy of torque wrenches?
First question is why? What are you doing that is that critical?
The reason I ask, is that torqueing up bolts isn't an exact science, attempting to completely control the torque can still result in bolt tension being wildly different.
The reason I ask, is that torqueing up bolts isn't an exact science, attempting to completely control the torque can still result in bolt tension being wildly different.
Re: Accuracy of torque wrenches?
According to my little engineers black book, using a torque wrench yields bolt torque results of + or - 25% !!
To get somewhere accurate + or - 4% check bolt elongation.
The wrench itself may be accurate but what about the installation technique etc?
To get somewhere accurate + or - 4% check bolt elongation.
The wrench itself may be accurate but what about the installation technique etc?
The Silver Bullet - BJ74
Where the actions at Ontrack 4wd Club
http://www.ontrack4wdclub.com/
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Where the actions at Ontrack 4wd Club
http://www.ontrack4wdclub.com/
[url]http://www.cams.com.au/[/url]
Re: Accuracy of torque wrenches?
What does your little engineers black book have to say about lubricated threads vs. dry threads?hulsty wrote:According to my little engineers black book, using a torque wrench yields bolt torque results of + or - 25% !!
To get somewhere accurate + or - 4% check bolt elongation.
The wrench itself may be accurate but what about the installation technique etc?
Tetanus rolling on 37's
Re: Accuracy of torque wrenches?
-Scott- wrote:Huh?chunderlicious wrote:if in doubt put a drop or 2 of 243 on the thread. bolts have a torque allowance for the torque wrench, not the bolt.
To quote our (in)famous ex-pat, "Please explain?"
243 is medium strength loctite blue in colour , it is the one that should be used on bolts that MAY be needed to come undone in the future.
EDIT: lubricated vs. dry threads is something that manufacturers of different bolts decide for themselves. CAT bolts are a non lubed bolt where as some of the hitachi bolts MUST be oiled before tensioning. But lubricated bolts do tighten/elongate something rediculous like 25% more than a dry bolt at a certain tension.
turbos are nice but i'd rather be blown
Re: Accuracy of torque wrenches?
My bad. I should've been more specific. This bit:chunderlicious wrote:-Scott- wrote:Huh?chunderlicious wrote:if in doubt put a drop or 2 of 243 on the thread. bolts have a torque allowance for the torque wrench, not the bolt.
To quote our (in)famous ex-pat, "Please explain?"
243 is medium strength loctite blue in colour , it is the one that should be used on bolts that MAY be needed to come undone in the future.
EDIT: lubricated vs. dry threads is something that manufacturers of different bolts decide for themselves. CAT bolts are a non lubed bolt where as some of the hitachi bolts MUST be oiled before tensioning. But lubricated bolts do tighten/elongate something rediculous like 25% more than a dry bolt at a certain tension.
And now, this bit:chunderlicious wrote:bolts have a torque allowance for the torque wrench, not the bolt.
chunderlicious wrote:But lubricated bolts do tighten/elongate something rediculous like 25% more than a dry bolt at a certain tension.
Re: Accuracy of torque wrenches?
Pretty much my point. There's no point having a torque wrench that's accurate to +/- 1% when the final result is still +/- 25%.hulsty wrote:According to my little engineers black book, using a torque wrench yields bolt torque results of + or - 25% !!
To get somewhere accurate + or - 4% check bolt elongation.
The wrench itself may be accurate but what about the installation technique etc?
Unless you're installing helicopter blades, it's probalby not necessary.
Re: Accuracy of torque wrenches?
That works in theory, but your fish scales would have to be equally accuratethehanko wrote:
measure out a nice neat number from the center of the head to somewhere on the handle (further out the better for greater accuracy). attache a fish type set of hanging scales to this point on the handle.
The worst part about being told you have Alzheimer's, is that it doesn't just happen once.
Re: Accuracy of torque wrenches?
are you saying that last 60 pound jew might have only been 50? you bastard! or you could be saying it might have been 70 - lets roll with that.oldmate wrote:That works in theory, but your fish scales would have to be equally accuratethehanko wrote:
measure out a nice neat number from the center of the head to somewhere on the handle (further out the better for greater accuracy). attache a fish type set of hanging scales to this point on the handle.
good point, compounding inaccuracy.
*there's a rock, drive over it :) there's a bigger rock, drive over it :twisted: there's an even bigger rock, oops broke it :oops: Upgrade broken bit :bad-words:
Goto *
Goto *
Re: Accuracy of torque wrenches?
-Scott- wrote:My bad. I should've been more specific. This bit:chunderlicious wrote:-Scott- wrote:Huh?chunderlicious wrote:if in doubt put a drop or 2 of 243 on the thread. bolts have a torque allowance for the torque wrench, not the bolt.
To quote our (in)famous ex-pat, "Please explain?"
243 is medium strength loctite blue in colour , it is the one that should be used on bolts that MAY be needed to come undone in the future.
EDIT: lubricated vs. dry threads is something that manufacturers of different bolts decide for themselves. CAT bolts are a non lubed bolt where as some of the hitachi bolts MUST be oiled before tensioning. But lubricated bolts do tighten/elongate something rediculous like 25% more than a dry bolt at a certain tension.
And now, this bit:chunderlicious wrote:bolts have a torque allowance for the torque wrench, not the bolt.
chunderlicious wrote:But lubricated bolts do tighten/elongate something rediculous like 25% more than a dry bolt at a certain tension.
All information told to me by loctite and drilled into my head by CAT at various times. both companies said to ask manufacturers of the bolt as to lubricate or not. both said lubricated bolts stretch a rediculous amount more than dry for a set torque and both said (but mainly cat) that the torque range of a bolt (e.g. 1/2" is 75lb. ft. +/- 10 lb. ft.) is because A. not every bolt will be at the right tension at that exact spot and B. because every torque wrench is slightly different.
if im wrong, so be it, i wont comment on anything like this again but this is the info myself and 20 others are getting on a yearly basis from these companies and our main equipment is CAT so why would they lie?
turbos are nice but i'd rather be blown
Re: Accuracy of torque wrenches?
Calm down. I'm not suggesting you're wrong. I couldn't understand what you were trying to say. I'm starting to understand now.chunderlicious wrote:All information told to me by loctite and drilled into my head by CAT at various times. both companies said to ask manufacturers of the bolt as to lubricate or not. both said lubricated bolts stretch a rediculous amount more than dry for a set torque and both said (but mainly cat) that the torque range of a bolt (e.g. 1/2" is 75lb. ft. +/- 10 lb. ft.) is because A. not every bolt will be at the right tension at that exact spot and B. because every torque wrench is slightly different.
if im wrong, so be it, i wont comment on anything like this again but this is the info myself and 20 others are getting on a yearly basis from these companies and our main equipment is CAT so why would they lie?
Re: Accuracy of torque wrenches?
The long and the short of it is:chunderlicious wrote:chunderlicious wrote:But lubricated bolts do tighten/elongate something rediculous like 25% more than a dry bolt at a certain tension.
All information told to me by loctite and drilled into my head by CAT at various times. both companies said to ask manufacturers of the bolt as to lubricate or not. both said lubricated bolts stretch a rediculous amount more than dry for a set torque and both said (but mainly cat) that the torque range of a bolt (e.g. 1/2" is 75lb. ft. +/- 10 lb. ft.) is because A. not every bolt will be at the right tension at that exact spot and B. because every torque wrench is slightly different.
if im wrong, so be it, i wont comment on anything like this again but this is the info myself and 20 others are getting on a yearly basis from these companies and our main equipment is CAT so why would they lie?
The goal is bolt tension, torque wrenches can only measure torque.
The relationship between torque and tension depends on a lot of factors, lubrication and bolt finish being the major ones.
Bottomline. Torque wrenches are only a guide.
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