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Cool
 

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Seek to understand,^Value
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My harbor freight torque wrench is acting up and caused me a lot of grief:
- How NOT to change your oil!

So, when I did my spark plugs this week, I couldn't use the torque wrench:
- Pictorial DIY for an M54 spark plug replacement on a 2002 BMW 525i E39 with 95K miles

End result. I need to calibrate mine too!

I read the calibration procedure listed in the reference:
- A Simple Way To Measure Torque Wrench Accuracy

But, I was going to use a far simpler method.

What I plan on doing is borrowing a similar torque wrench (one that is "assumed" accurate) and squaring the two torque wrenches against one another on a double-ended bolt.

I think I can make a double-ended bolt simply by buying a female-to-female fitting, and then screwing the two similar bolts into each end.

Now I effectively have a steel bar with hex nuts on the end that won't turn.

If I turn one torque wrench to, say, 20 lb-ft, the other should read the same value.

Do you think this KISS method will work?
 

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BB
Your KISS method should work fine as one wrench simply resists the torque of the other. However, most torque wrenches, including the HF torque wrenches that I have, have rotating adjustment scales. Using this method, you can compare two wrenches but you cannot calculate how much out-of-calibration your torque wrench actually is.

I came up with a much simpler method to home-calibrate your torque wrench. It requires a spring scale that measures pounds, up to at least 50 lbs (which every respectable big fish flyfisherman should have:)). Larger is better, especially when you try to calibrate the 1/2" torque wrenches. Take your torque wrench and set it to say 10 ft-pounds. Find a nut or bolt that is torqued way above that value and the axis is set vertically, to eliminate the weight of the wrench from the calculation (the torque wrench should be horizontal). Place the scale hook at the hand application point on the torque wrench. Measure that distance from the socket axis (inches). Pull on the scale and take a reading when it clicks. Do this a number of times to get a mean average force (lb). Multiple by the distance (inches) and divide by 12 to get ft-lbs of torque. The difference is how much out of calibration your torque wrench is. Repeat at the next setting (20 ft-lb) and on up the range until you know how close your torque wrench is across the complete range of settings.


NOTE: Tha accuracy of this calibration technique is only as accurate as the scale used. If your scale has an inaccuacy of +/- 3 lbs, that inaccuracy gets multiplied by the length of the lever arm.
 

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Under the lift arms
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These are the same people who use torque wrenchs to take stuff off, so all I can say is baby steps baby steps
 

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Under the lift arms
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Ok sorry little sour some times here, anyway some real info ..... don't drop it, one click and stop and never.use it to remove stuff

Sent from my ADR6300 using Bimmer App
 

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Ok sorry little sour some times here, anyway some real info ..... don't drop it, one click and stop and never.use it to remove stuff

Sent from my ADR6300 using Bimmer App
Maybe I'm wrong but I thought the OP asked how to calibrate a torque wrench, not how to use one. :dunno:
 

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Well, My KISS principle.

Although I like the click-type torque wrench, I prefer the "inexpensive needle-type" torque wrench because it is low-tech and very much fool-proof.

How do I calibrate my torque wrench:
- Clamp a bolt onto a vise on a bench, find the appropriate socket and use it with the torque wrench.
- Get a 1-gallon container and fill it with water = approx. 8.35 lbs.
- Hang the container roughly at 1 foot away from the bolt's center.
It should read 8.35 ft-lb.

- Likewise, a 5-gallon bucket full of water weighs approx 42 lbs.
 

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Under the lift arms
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Just pointing out that if u don't drop it and u use it correct u will not have to calibrate it, I've used the same snap on,torque wrench for years and years , one of my clearest tools :) still looks like new

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Freude am Fahren
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Just pointing out that if u don't drop it and u use it correct u will not have to calibrate it, I've used the same snap on,torque wrench for years and years , one of my clearest tools :) still looks like new

Sent from my ADR6300 using Bimmer App
Snap On wrench is good, HF wrench isn't. That is Bluebee's fundamental problem.
 

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BB
Your KISS method should work fine as one wrench simply resists the torque of the other. However, most torque wrenches, including the HF torque wrenches that I have, have rotating adjustment scales. Using this method, you can compare two wrenches but you cannot calculate how much out-of-calibration your torque wrench actually is.

I came up with a much simpler method to home-calibrate your torque wrench. It requires a spring scale that measures pounds, up to at least 50 lbs (which every respectable big fish flyfisherman should have:)). Larger is better, especially when you try to calibrate the 1/2" torque wrenches. Take your torque wrench and set it to say 10 ft-pounds. Find a nut or bolt that is torqued way above that value and the axis is set vertically, to eliminate the weight of the wrench from the calculation (the torque wrench should be horizontal). Place the scale hook at the hand application point on the torque wrench. Measure that distance from the socket axis (inches). Pull on the scale and take a reading when it clicks. Do this a number of times to get a mean average force (lb). Multiple by the distance (inches) and divide by 12 to get ft-lbs of torque. The difference is how much out of calibration your torque wrench is. Repeat at the next setting (20 ft-lb) and on up the range until you know how close your torque wrench is across the complete range of settings.

NOTE: Tha accuracy of this calibration technique is only as accurate as the scale used. If your scale has an inaccuacy of +/- 3 lbs, that inaccuracy gets multiplied by the length of the lever arm.
The method in the link a few post above uses a long lever arm, about 7-8 feet and a gallon of water, which is a precise load , and more accurate than a fish scale. Fish scales are cheap and their accuracy is quite poor.

The longer the arm and the more accurate the true weight at the end, yields the greatest accuracy.
 

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Snap On wrench is good, HF wrench isn't. That is Bluebee's fundamental problem.
Your personal problem with BB is showing here and in past threads.
 

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Been there done that...
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Your personal problem with BB is showing here and in past threads.
:confused: are you suggesting a HF torque wrench is to be used on anything, but maybe the lug bolts on an E39? :dunno:

if so, your personal sympathy to BB is showing here and in the past threads :eeps: I mean it's cool she documented it and all, but "DONT USE $HITTY TOOLS" is pretty much a bottom line in ANY repair.

I bought my HF torque wrench for $10 and use it EXCLUSIVELY on lug bolts and as a breaker bar sometimes, if I wanted anything more or less accurate I'd have to spend over x10 that just to get a Craftsman one, let alone Snap-ON.
 

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Discussion Starter · #16 ·
Great tips. The link from the 2nd post is great. Also Fudman's idea is great.

I am asking, because I want to be sure my torque wrenches are in spec, and I don't want to waste $$ sending the wrenches to calibration shops when there is no need to (I hope). My wrenches are always taken care of, not banged. They are always reset to "0". My only concern is they rest in my garage which is cold, and the temperature swing from summer to winter and back to summer is significant where I live.
I am not sure if this will affect the calibration or not, but I want to somehow check this, so I am sure I have the correct setting, especially when I deal with the small bolts/torque wrench which is using the in-lbs scale...

Thanks guys
 

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Great tips. The link from the 2nd post is great. Also Fudman's idea is great.

I am asking, because I want to be sure my torque wrenches are in spec, and I don't want to waste $$ sending the wrenches to calibration shops when there is no need to (I hope). My wrenches are always taken care of, not banged. They are always reset to "0". My only concern is they rest in my garage which is cold, and the temperature swing from summer to winter and back to summer is significant where I live.
I am not sure if this will affect the calibration or not, but I want to somehow check this, so I am sure I have the correct setting, especially when I deal with the small bolts/torque wrench which is using the in-lbs scale...

Thanks guys
My buddy and I politely asked a Costco tire center to check our torque wrenches, as every one of them has a torque calibration tool. They check their wrenches monthly and log the results. They CANNOT, fix or adjust the wrench, only determine if they are in calibration or not. (bring donuts, or other savory item, when they are not busy ;) ). The results were his two practically brand new Craftsman wrench were both out of spec, and my 20 year old Utica wrench was right on the money. http://www.cooperpowertools.com/brands/torque/index.cfm

Even if you have to pay a calibration shop to check your wrenches and adjust them, it is not terribly expensive, and not something that would need to be done more than every few years once you start from a known point. From some checking I have done, it is typically around $35 to check, and another $35 or so for adjustment with calibration certificate.
 

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Doru,

As you know, torque wrench is most crucial when dealing with small nuts and bolts such as Water Pump nuts, Strut Mount nuts etc.

With Larger bolts such as wheel lugs, whether you torque it to 110 Nm or 120 Nm, it makes absolutely no difference. There is room for error for the large bolts.

Back to the small bolts (in my "book", anything that requires a socket size of 10mm to 13mm), you need to be careful.
The click-type torque wrench: I believe it needs some sort of lubrication (so the dog gears can slide properly); if not lubed properly, this type of torque wrench can over-tighten things!

This is internal anatomy of a click-type torque wrench:
http://www.tegger.com/hondafaq/torque_wrench/index.html

I am a simplistic guy, I use the low-tech dial-type torque wrench, which is fool-proof.

As already mentioned, the click-type wrench is a bit more precise but it requires some TLC, and I don't have time for TLC, so I stick to dial-type torque wrench!
 

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Discussion Starter · #19 ·
My buddy and I politely asked a Costco tire center to check our torque wrenches, as every one of them has a torque calibration tool. They check their wrenches monthly and log the results. They CANNOT, fix or adjust the wrench, only determine if they are in calibration or not. (bring donuts, or other savory item, when they are not busy ;) ). The results were his two practically brand new Craftsman wrench were both out of spec, and my 20 year old Utica wrench was right on the money. http://www.cooperpowertools.com/brands/torque/index.cfm

Even if you have to pay a calibration shop to check your wrenches and adjust them, it is not terribly expensive, and not something that would need to be done more than every few years once you start from a known point. From some checking I have done, it is typically around $35 to check, and another $35 or so for adjustment with calibration certificate.
These are the key ingredients right here: quality tools. That's what I have and I sunk a considerably chunk of money in my tools hoping they will last. Great piece of info, which is peace of mind for me. Thanks.
 

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There is definitely a story there, a Utica wrench costs $300, a Craftsman is what, $60? But again, without the testing, you really don't know for certain. I believe it would be worth the money to have the proper calibration tests done as a starting point, any adjustments made, and work from there.
 
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