How do you check Torque Wrench accuracy?

junglejeep · 10-18-2006, 12:45 PM

I have a click style torque wrench and want to check and see if it reads right. How would I do this?

If it's not right then how do you calibrate it?

**Divinitous** · 10-18-2006, 12:51 PM

http://home.jtan.com/~joe/KIAT/kiat_3.htm

junglejeep · 10-18-2006, 01:17 PM

Any other ideas? I don't really like the idea of building a toe smasher on my vise. It may work well but there has to be another way. What types of shops should I look at locally to have it calibrated?

Matt in TN · 10-18-2006, 02:36 PM

Honestly I wouldn't fool with it unless you think it's way off - even then, you'll be cheaper to buy a new wrench than to "calibrate" your old one.

Torque specs are really specified as an "easy" way to guess at the longitudinal thread stretch, and even if your torque measurements are perfect (which is VERY rare), you're still looking at something like 30% error on the thread strain - it's all just a crapshoot anyway.

That being said - I'm careful to torque bolts to specifications, using the same (dry or lubricated) type of conditions. After that - I don't worry about it too much.

junglejeep · 10-18-2006, 02:45 PM

Matt you're probably right. A buddy of mine says just german torque them with a closed end wrench and call it good. Atleast I have one I guess.

**JeeperDon** · 10-18-2006, 06:03 PM

I think the most important thing in using a torque wrench is just to get a multi-bolt setup at an even setting, like axle u-bolts.

**Jerry Bransford** · 10-18-2006, 06:26 PM

Quote:

Originally Posted by JeeperDon

I think the most important thing in using a torque wrench is just to get a multi-bolt setup at an even setting, like axle u-bolts.

Exactly. There is a range of acceptable tightnesses so it's not usually important you get a particular bolt to a precise tightness. It's more important that adjoining bolts/nuts like on heads and wheels just be tightened to the same tightness. That just means a more important trait of any torque wrench is the repeatability of its settings. So to me, it's no big deal if my Harbor Freight Tools torque wrench says it's tightened to 90 ft-lbs when it's really 94 ft-lbs. I really just want all the lug nuts or head bolts to be tightened equally to prevent warping.

junglejeep · 10-19-2006, 07:32 AM

Thanks Jerry and JeeperDon for that logic I never thought of it that way. In that case who cares I'm just gonna set it and use it.

TJ_with_Tusks · 10-24-2006, 06:25 AM

For craftsman torque wreches, you are supposed to take them to sears and have them calibrated once a year.

**JeeperDon** · 10-24-2006, 03:44 PM

Quote:

Originally Posted by TJ_with_Tusks

For craftsman torque wreches, you are supposed to take them to sears and have them calibrated once a year.

For free???

Vinman · 10-24-2006, 08:14 PM

Quote:

Originally Posted by Jerry Bransford

Exactly. There is a range of acceptable tightnesses so it's not usually important you get a particular bolt to a precise tightness. It's more important that adjoining bolts/nuts like on heads and wheels just be tightened to the same tightness. That just means a more important trait of any torque wrench is the repeatability of its settings. So to me, it's no big deal if my Harbor Freight Tools torque wrench says it's tightened to 90 ft-lbs when it's really 94 ft-lbs. I really just want all the lug nuts or head bolts to be tightened equally to prevent warping.

I completey agree with this.

Another thing I always do is adjust the torque setting on the wrench (click type) as low as it can go any time I am not using it. I see people set the torque setting to a specific setting, tighten the nut/bolt and then store the wrench without turning the setting back down to 0 or less.
This method causes constant pressure on the internal spring which, I'm sure, will contribute to reducing the wrench's accuracy.

Vince

**sentinal02** · 10-24-2006, 09:34 PM

all you really need is a spring scale like you find in science class and solid anchor point for the head (vice). measure out 1 foot from the center of the wrench's head (the middle of the square for the socket) and attach your scale so it can't slide on the handle. a thick rubber band placed on the handle and some twine will suffice for small measurements. now set you wrench to oh say 20 ft lbs and put the head in your vice (to simulate a bolt. you could put a bolt in the vice and put a socket on the wrench to fit if you like). now apply the turning force by pulling on the other end of the scale. when you hear the click, check the reading on the scale. it should match the setting on the wrench. if not then you'll know how far off it is. keep in mind that the variance probably isn't uniform though. it may be off 1 ft-lb at 20 ft-lbs, and off by 7 ft-lbs at 50 ft-lbs.

**coonash** · 10-25-2006, 11:37 AM

Find a local vendor who sales and services pressure gauges. They also will calibrate torque wrenches. Our local rep told me that craftsman is the worst for calibrating. They are made by the lowest bidder and change from year to year.

dawnskaybug · 10-30-2006, 01:40 AM

I use Torque wrenches everyday at my job. If we find a tourque wrench not stored at the lowest setting we turn it in to get calibrated. Believe it or not alot get thrown away because they cant be fixed because there not stored at there lowest setting. Also dropping it will throw it off.

Indy · 11-02-2006, 09:58 AM

Quick and simple method. Take a known weight and a known length. example, measure out 1 foot from the socket end of your torque wrench, assuming the wrench is more than 1' long. Attach the socket end to a fixed object. Set wrench to 10lbs, or whatever weight you have handy. Apply 10lb weight to the 1 foot mark on the wrench. Click? you're calibrated.