Torque wrench accuracy.

[bradley8795]

I have been told and was under the impression that a torque wrench is not very accurate between 20% of its upper and lower limits. Looking at the calibration information though makes that seem incorrect. If you look below it shows clearly that the torque wrench is very accurate all the way to its max limit. But not very accurate in the first 20%.

So did I just understand incorrectly that it is inaccurate within 20% of its UPPER and LOWER limits or is this new?


Sent from my iPhone using Tapatalk

 

[Charles (in GA)]

That is a 100 lb/ft torque wrench. Thus ANSI and European and Australian standards (which all mimic each other) specify that the tool be accurate and calibrated from 20% of its max to its max rating, that is why they tested it at 20, 60 and 100. It MIGHT be accurate below 20% of max, but you have no way of knowing and no assurance of such. I'm surprised that the tool has a range (according to the test sheet) as 5 lb/ft to 100lb/ft.

" But not very accurate in the first 20%. "

What do you mean by this? I would say that the low end, 20 lb is spot on. In fact, the largest error is only 1.1%, with a max of 2% (many torque wrenches are specified at 4% and sometimes even 6% in reverse) that you have a nearly perfect tool there.

Charles

 

[Hiball]

I dont own any electric torque wrenches nor understand how they work, but obviously based off the calibration sheet its seems very accurate from top to bottom. I think the majority of the upper/lower inaccuracy is aimed towards clicker type torque wrenches. Im just guessing that the electric type torque wrenches utilize a strain type mechanism? If so that explains the accuracy.

 

[Carbonblk46]

Was that from you sending in to get calibrated? If so how much does Snap On charge to recalibrate?

 

[introvertedtraveler]

Was that from you sending in to get calibrated? If so how much does Snap On charge to recalibrate?

you get that sheet when you first purchase one off the truck. Snap On trucks have a torque wrench check tool mounted somewhere on the trucks

 

[Carbonblk46]

you get that sheet when you first purchase one off the truck. Snap On trucks have a torque wrench check tool mounted somewhere on the trucks

Never got one with my Techangle years ago hmmm. Yeah my old truck guy had one but the new guy doesn't. Everytime I ask how much to calibrate hes tries to sell me the newer Techangle.

 

[SMKS]

Most torque wrenches claim to be accurate from 20-100% of scale, which is what the OP found. So a 100 ft-lbs torque wrench will be considered accurate from 20-100 ft-lbs. Check your owner's manual, but this is true for most wrenches.

The oft-repeated claim of "they're not accurate at the top or bottom of the range" isn't accurate. In most cases, the wrench is only not considered accurate in the bottom 20% of scale.

 

[burke753]

Never got one with my Techangle years ago hmmm. Yeah my old truck guy had one but the new guy doesn't. Everytime I ask how much to calibrate hes tries to sell me the newer Techangle.

All my torque wrenches are SnapOn and I recently launched my 3/8 off a truck and it hit the ground like a sack of taters right in front of the Snap-On man. He called Snap-On right up and they charge $38 for recalibration and if it's broken it's $61 to repair and recalibrate.

So I sent it off and it ended up not being broken just out of calibration so they did their thing, recertified and sent it back. Takes about 3 weeks before you'll see it again if you have your dealer send it off.


Sent from my iPhone using Tapatalk

 

[Carbonblk46]

All my torque wrenches are SnapOn and I recently launched my 3/8 off a truck and it hit the ground like a sack of taters right in front of the Snap-On man. He called Snap-On right up and they charge $38 for recalibration and if it's broken it's $61 to repair and recalibrate.

So I sent it off and it ended up not being broken just out of calibration so they did their thing, recertified and sent it back. Takes about 3 weeks before you'll see it again if you have your dealer send it off.


Sent from my iPhone using Tapatalk

Wow would of loved to see that one. Might have to call snap on directly as it seems my guy won't be sending mine off! Figured it would be a lot more.


Sent from my iPhone using Tapatalk

 

[burke753]

Wow would of loved to see that one. Might have to call snap on directly as it seems my guy won't be sending mine off! Figured it would be a lot more.


Sent from my iPhone using Tapatalk

Yeah he snuck up on me and scared me half to death and when I turned around I of course knocked to most expensive tool I had in the vicinity to the ground.

But yeah just give them a call. They'll take care of you. Snap-On customer service is top notch.

Their dealers. Not so much haha


Sent from my iPhone using Tapatalk

 

[rsanter]

most good torque wrenches are +/- 2% within the center 80% of their range

better torque wrenches are accurate to +/- 1% within the center 80% of their range and +/- 2% outside of that range

bob

 

[1foxracing]

Here is my Wright Tool models. Notice the Supervisor is the same guy as the SnapOn.

 

[country83]

Here is my Wright Tool models. Notice the Supervisor is the same guy as the SnapOn.

Interesting..CDI must be the OEM for Wright as well.

In response to the OP, torque wrenches are calibrated from 20-100% of scale, so that 100 ft-lb ATECH is accurate from 20 to 100 ft-lbs. The electronic ones are decently accurate below 20%, but not as accurate as above 20%. Many mechanical wrenches won't even work below 20% of full scale.

 

[guy48065]

most good torque wrenches are +/- 2% within the center 80% of their range

better torque wrenches are accurate to +/- 1% within the center 80% of their range and +/- 2% outside of that range

bob

This is wrong and just perpetuates the misconception of the OP. As everyone else has stated, all torque wrenches are calibrated from 20-100% of range.

"Good" and "better" are opinions--all have specifications. IMO a "good" wrench is any that can be adjusted to meet its spec--even a lowly HF.
Typical specs for various types are:
Click-type normally ±4%cw, ±6%ccw (if rated for ccw use).
Dial-type ±4 (most) or ±3 (some), cw or ccw.
Digital ±2 both directions, typically.