Torque Wrench Accuracy- How to easily test

[Toys4Life C5]

A few days ago I was torquing a suspension bolt and I just had that feeling that I was going way too tight .... and I was seriously starting to wondering if my torque wrench is no longer accurate!

It bothered me a lot - so I found out how to make sure my torque wrench is in fact accurate and now I can sleep at night knowing my repair is correct.

I put together this short video showing just how easy the process is.

 

[BrandoJames]

Thanks for making that video. Just to be clear, you hung a 25 lb weight off the handle, which is 18 inches long, so 25 lbs x 1.5 ft = 37.5 ft/lbs. The first time you tested it, what was the torque wrench set to initially when it clicked? Right at 37.5 ft/lbs?

If it's adjusted correctly, then it won't click at 37.5 ft/lbs until you add slight pressure on the handle. Is that right? Thanks.

 

[giants]

Thanks. Do you have any Harbor Freight/Pittsburgh torque wrenches that you could make a video on how to adjust them?

 

[tomwil]

Can a Digital Torque Adapter be used to check / calibrate a torque wrench?

https://www.harborfreight.com/12-in-drive-digital-torque-adapter-63917.html

 

[visionguru]

Can a Digital Torque Adapter be used to check / calibrate a torque wrench?

https://www.harborfreight.com/12-in-drive-digital-torque-adapter-63917.html

I have the Powerbuilt version. From the user manual, it seems to me that these adapters are designed for calibrating torque wrenches.

 

[Szilagyi]

I have the Powerbuilt version. From the user manual, it seems to me that these adapters are designed for calibrating torque wrenches.

The youtube user ClientGraphics uses these and he had two of his tested at a calibration shop and they were within 2% accuracy (IIRC) across their whole torque range. I think they are a great thing to have around the shop.

 

[Shadowdog500]

Can a Digital Torque Adapter be used to check / calibrate a torque wrench?

https://www.harborfreight.com/12-in-drive-digital-torque-adapter-63917.html

It would be neat to put that between the vise and the torque wrench during the hanging weight test as an extra cross check.

Chris

 

[visionguru]

The youtube user ClientGraphics uses these and he had two of his tested at a calibration shop and they were within 2% accuracy (IIRC) across their whole torque range. I think they are a great thing to have around the shop.

I had the Powerbuilt adapter for years and hadn't been confident about accuracy, until I purchased 1/4, 3/8, 1/2 Snap On Techangles. The adapter is virtually dead on when tested against those new Snap Ons. I would say that these adapters are totally suitable to calibrate click-type torque wrenches, and that's what they are designed for.

 

[katit]

Can a Digital Torque Adapter be used to check / calibrate a torque wrench?

https://www.harborfreight.com/12-in-drive-digital-torque-adapter-63917.html

I got QUINN 3/8 torque wrench and yes, it does have functionality to measure torque

 

[Toys4Life C5]

Thanks for making that video. Just to be clear, you hung a 25 lb weight off the handle, which is 18 inches long, so 25 lbs x 1.5 ft = 37.5 ft/lbs. The first time you tested it, what was the torque wrench set to initially when it clicked? Right at 37.5 ft/lbs?

If it's adjusted correctly, then it won't click at 37.5 ft/lbs until you add slight pressure on the handle. Is that right? Thanks.

Yes, I set the reading to 37.5 ft-lbs and blew past it. It finally held at 42 ft-lbs. After adjusting the mechanism in the handle, it holds at 37.5 ft-lbs until I add a smidge more weight with my pinky finger. Close enough for me

 

[seber]

You have a built in addition to the weight being applied. The weight of the handle adds to the 25 pounds. Weigh the handle at the end while the head is supported and allowed to pivot freely. Add this weight times the handle length to your product of 25 x 1.5.

 

[dutchgray]

I just use a beam type torque wrench and an 8 point socket to couple them together, check at a few different values, you will soon know if is alright, if its close to the correct value and consistent then the clicker is fine, 60 to 90 degrees angle between the wrenches one in each hand, high values on a 1/2" wrench would get difficult so you would need to build a rig or get help.

 

[Toys4Life C5]

Thanks. Do you have any Harbor Freight/Pittsburgh torque wrenches that you could make a video on how to adjust them?

Sorry, I do not.

 

[Toys4Life C5]

Can a Digital Torque Adapter be used to check / calibrate a torque wrench?

https://www.harborfreight.com/12-in-drive-digital-torque-adapter-63917.html

I would not use that to check/calibrate. It is another sensitive device that could easily be out of calibration.

If my 25 pound weight gets cold, or gets dropped from 30 feet in the air, it is still going to weigh 25 pounds which makes it a much better tool to calibrate with IMO..

 

[B_Bimmer]

I just use a beam type torque wrench and an 8 point socket to couple them together, check at a few different values, you will soon know if is alright, if its close to the correct value and consistent then the clicker is fine, 60 to 90 degrees angle between the wrenches one in each hand, high values on a 1/2" wrench would get difficult so you would need to build a rig or get help.

This is my method as well.

 

[Toys4Life C5]

It would be neat to put that between the vise and the torque wrench during the hanging weight test as an extra cross check.

Chris

You could use the 25#weight to make sure the calibrator is calibrated, before using the calibrator to calibrate the torque wrench - or just use the 25# weight to calibrate the torque wrench. I am much more confident the 25# weight will not change over time or abuse than the calibrator. I am not very smart so I have to keep it simple

 

[Toys4Life C5]

A few days ago I was torquing a suspension bolt and I just had that feeling that I was going way too tight .... and I was seriously starting to wondering if my torque wrench is no longer accurate!

It bothered me a lot - so I found out how to make sure my torque wrench is in fact accurate and now I can sleep at night knowing my repair is correct.

I put together this short video showing just how easy the process is.

I got to thinking and was wondering if calibrating the torque wrench at 37.5 ft lbs would also make it accurate at higher readings. I hung a 50lb weight today at 18" and it was right at 75 ft lbs. Makes me feel even better about the accuracy of this procedure.

 

[Shadowdog500]

You could use the 25#weight to make sure the calibrator is calibrated, before using the calibrator to calibrate the torque wrench - or just use the 25# weight to calibrate the torque wrench. I am much more confident the 25# weight will not change over time or abuse than the calibrator. I am not very smart so I have to keep it simple

It could be a backup to see if your scale that told you that your weight was 25lb. Is correct? .

I have access to a torque wrench tester. it is effectively a highly accurate dial type of torque wrench that is put in a box instead of a handle. The testers usually have a NIST or NIST traceable certification on its accuracy. The newer ones are digital.

Years ago I had access to a really old wall mounted torque tester that looked like it may have been left over from WW2 or even before ww2. It was basically a heavy weight on a solid shaft pendulum. The pendulum was a pointer that pointed to a scale that read 0 at the bottom and the max torque at 90° from The bottom. You would attach the torque wrench at the top of the pendulum (which was the pivot point) and as you pulled the torque wrench the torque would increase as the weight swung out and up from vertical to horizontal. It’s identical to holding a vertical suspended 20lb. sledge hammer by the top of the handle with one hand and trying to rotate your wrist to bring the sledgehammer to the horizontal position. Most people won’t be able to do it because the torque increases as a function of the angle. If you have a known sledge hammer weight and a known sledge handle handle length the torque at any angle can be calculated.

Chris

 

[Toys4Life C5]

It could be a backup to see if your scale that told you that your weight was 25lb. Is correct? .

I have access to a torque wrench tester. it is effectively a highly accurate dial type of torque wrench that is put in a box instead of a handle. The testers usually have a NIST or NIST traceable certification on its accuracy. The newer ones are digital.

Years ago I had access to a really old wall mounted torque tester that looked like it may have been left over from WW2 or even before ww2. It was basically a heavy weight on a solid shaft pendulum. The pendulum was a pointer that pointed to a scale that read 0 at the bottom and the max torque at 90° from The bottom. You would attach the torque wrench at the top of the pendulum (which was the pivot point) and as you pulled the torque wrench the torque would increase as the weight swung out and up from vertical to horizontal. It’s identical to holding a vertical suspended 20lb. sledge hammer by the top of the handle with one hand and trying to rotate your wrist to bring the sledgehammer to the horizontal position. Most people won’t be able to do it because the torque increases as a function of the angle. If you have a known sledge hammer weight and a known sledge handle handle length the torque at any angle can be calculated.

Chris

In my case it is an undamaged weight plate - so its accurate. But I see your point - if you just had a chunk of steel you would want to weight it first on a quality scale.

 

[Toys4Life C5]

You have a built in addition to the weight being applied. The weight of the handle adds to the 25 pounds. Weigh the handle at the end while the head is supported and allowed to pivot freely. Add this weight times the handle length to your product of 25 x 1.5.

Interesting thought and good point but after careful thought I think it is moot as a new torque wrench does not come with instructions to deduct the weight of the wrench when torquing horizontal bolts (ie wheel studs) and not deducting the weight of the wrench when torquing vertical bolts (ie head bolts) so i think it is negligible. If you are doing a 20 ft lb bolt, maybe use a smaller inch-pound torque wrench if you are concerned about the weight of the wrench.

 

[nieuport17]

I just use a beam type torque wrench and an 8 point socket to couple them together, check at a few different values, you will soon know if is alright, if its close to the correct value and consistent then the clicker is fine, 60 to 90 degrees angle between the wrenches one in each hand, high values on a 1/2" wrench would get difficult so you would need to build a rig or get help.

This is my way too. I use 12 point socket to couple them.
I think this is easy way.

 

[Shadowdog500]

Interesting thought and good point but after careful thought I think it is moot as a new torque wrench does not come with instructions to deduct the weight of the wrench when torquing horizontal bolts (ie wheel studs) and not deducting the weight of the wrench when torquing vertical bolts (ie head bolts) so i think it is negligible. If you are doing a 20 ft lb bolt, maybe use a smaller inch-pound torque wrench if you are concerned about the weight of the wrench.

to be technically accurate the weight of the wrench doesn’t matter when using a properly calibrated torque wrench in any orientation because it measures the total torque at the head which is the sum of all of the torques which includes the weight of the wrench along with the applied torque from you pulling on the wrench. You could wrap a properly calibrated torque wrench handle with 10lb of lead solder and it would still work accurately in any orientation because the total torque that the wrench would click at would be the sum of the torque on the head from the weight on the handle along with the torque from you pulling on the handle. Your applied force on the handle would be 10 Lb less when pulling down and 10lb more when pulling up.

When you calibrated the torque wrench by hanging a known weight to it, the torque measurement on the head included the torque from the weight you hung plus the torque from the weight of the torque wrench.

My torque wrench weighs about around 2.5 lb and is around 24” long. So we can assume that the torque from the weight of the wrench alone during a horizontal calibration is somewhere around 2.5lb x 12” = 30 in lb or 2.5 ft lb. you could find the wrenches balance point to figure out the arm more accurately if you want.

If you used my torque wrench during the calibration process and hung the 25 lb weight 21” from the torque head you would assume that the torque wrench was calibrated for 1.75 ft x 25 lb = 43.75 ft lb when in fact it would be calibrated for around:
1.75 ft x 25lb. + 1 ft x 2.5 lb = 43.75ft lb + 2.5 ft lb = 46.25 ft lb

 

[Toys4Life C5]

to be technically accurate the weight of the wrench doesn’t matter when using a properly calibrated torque wrench in any orientation because it measures the total torque at the head which is the sum of all of the torques which includes the weight of the wrench along with the applied torque from you pulling on the wrench. You could wrap a properly calibrated torque wrench handle with 10lb of lead solder and it would still work accurately in any orientation because the total torque that the wrench would click at would be the sum of the torque on the head from the weight on the handle along with the torque from you pulling on the handle. Your applied force on the handle would be 10 Lb less when pulling down and 10lb more when pulling up.

When you calibrated the torque wrench by hanging a known weight to it, the torque measurement on the head included the torque from the weight you hung plus the torque from the weight of the torque wrench.

My torque wrench weighs about around 2.5 lb and is around 24” long. So we can assume that the torque from the weight of the wrench alone during a horizontal calibration is somewhere around 2.5lb x 12” = 30 in lb or 2.5 ft lb. you could find the wrenches balance point to figure out the arm more accurately if you want.

If you used my torque wrench during the calibration process and hung the 25 lb weight 21” from the torque head you would assume that the torque wrench was calibrated for 1.75 ft x 25 lb = 43.75 ft lb when in fact it would be calibrated for around:
1.75 ft x 25lb. + 1 ft x 2.5 lb = 43.75ft lb + 2.5 ft lb = 46.25 ft lb

I see what you mean and agree.

 

[recountryman]

But wouldn't using a weight just mean its accurate to that weight but your not going thru the scale of the wrench itself so you really still don't know how accurate it is beyond that... right? Shouldn't you be using a means that will check it thru a range?

 

[Danglerb]

I saw a youtube that used one, so I bought a luggage scale off ebay for about $5, makes a quick test easy enough. Various types, typically a ******** one end to loop around the handle and something to grip or a hook like a hanger on the other end.

Not this one, like it though. http://www.ebay.com/itm/Luggage-Hoo...ng-Digital-LCD-Ounces-Weight-KG-/323912963261

 

[visionguru]

I saw a youtube that used one, so I bought a luggage scale off ebay for about $5, makes a quick test easy enough. Various types, typically a ******** one end to loop around the handle and something to grip or a hook like a hanger on the other end.

Not this one, like it though. http://www.ebay.com/itm/Luggage-Hoo...ng-Digital-LCD-Ounces-Weight-KG-/323912963261

It's pointless using a luggage scale to test torque wrench, because those can easily be 20% off, and your torque wrench won't be that much off if not abused. Spend $20 more to get a digital torque adapter, which can be used for calibration and for cases when the torque wrench is too long to use.

 

[Danglerb]

$5 scale is accurate to less than a pound if not ounces. We use it to check baggage weight and cross check with a postal approved scale, its within ounces, goes to 40kg.

If the cheap scales were off by even 1% people would be screaming about them all over the internet due to baggage wt limits on flights.

 

[joe_pinehill1]

If you are curious, check your area for a test and calibration lab. We have a local shop that charges about $30 to check and calibrate torque wrenches.

 

[lardy1]

I use an old beam type that I trust to keep my El Cheapo torque adapter honest. Then check my click types against the adapter. I don't have top shelf torque wrenches. But I take care of them and check them against one another and the digital meter and they are within my comfort zone. Not complicated at all.

 

[Toys4Life C5]

If you are curious, check your area for a test and calibration lab. We have a local shop that charges about $30 to check and calibrate torque wrenches.

Not a bad idea, but if you have a known weight, a short rope and can do some simple math - there is no reason to calibrate it yourself and save the money.

If I was building jet engines and needed to be accurate ti the hundredth of a ft/lb that might be a different story.

 

[BrandoJames]

If you are curious, check your area for a test and calibration lab. We have a local shop that charges about $30 to check and calibrate torque wrenches.

For a DIY'er with an inexpensive torque wrench ($40 Tekton), a $30 calibration doesn't make sense. I can buy a new wrench with a few extra bucks.

 

[visionguru]

$5 scale is accurate to less than a pound if not ounces. We use it to check baggage weight and cross check with a postal approved scale, its within ounces, goes to 40kg.

If the cheap scales were off by even 1% people would be screaming about them all over the internet due to baggage wt limits on flights.

I have a spring type luggage scale. I'd be happy if it can be accurate to 10%, because every time it is used, the spring has to be stretched a lot and could loose tension. Digital type could be more accurate, but 1% is "dead on" kind of accuracy. I doubt a $5 scale was calibrated, but most torque wrenches were calibrated before out of factory.

From Snap On literature:
"ISO standard 6789:2003 specifies the calibration requirements for torque wrenches at one year or 5,000 cycles."

For most DIYers, 5000 cycles is a lifetime. As long as the torque wrench is not abused, it should keep its calibration for a long time.

 

[Danglerb]

I have a spring type luggage scale. I'd be happy if it can be accurate to 10%, because every time it is used, the spring has to be stretched a lot and could loose tension. Digital type could be more accurate, but 1% is "dead on" kind of accuracy. I doubt a $5 scale was calibrated, but most torque wrenches were calibrated before out of factory.

Mine was $2.95 shipped, its digital, and matches the postal approved scale almost to the oz. with 40 to 70 lb suitcases.

 

[bastel]

Mine was $2.95 shipped, its digital, and matches the postal approved scale almost to the oz. with 40 to 70 lb suitcases.

Using cheap ones from the supermarket, too (those 40kg ones with that annoying beeeep, right ). Same results, 31kg were 31kg when weighted at the post office, exact up to a few 10 grams. My wrench was no good, though, was clicking to early, I need to add 10 Nm to get to the real value. Dunno if it was my way to measure it, simply put the 0.5" socket into the vise and pulled. Anyway it's ok, all I use it is to tighten lug bolts on a car to 110 Nm, and I guess a little too much doesn't hurt it.