Help with Torque Wrenches

[MattB77]

Hi, I need some help with the finer details of torque wrenches.

I bought my 1/2" torque wrench probably 15 years ago now and it was rated 10-150lbft, so I thought that'll do me and never thought anymore about it. Recently though I've heard that a torque wrench is only accurate above 20% of its maximum, so above 30lbft for mine. Well that's probably above half of the settings I've ever used it for! So should I buy another, maybe a 3/8" or even a 1/4" one?

Now I'm only a home mechanic, so I guess that torque wrench has been used on average say a dozen times a year for around 15 years as I've not used it for wheel nuts. So should I replace it? I'm not sure how long they last but it's been well looked after. It was never an expensive one so not worth the money to get it recalibrated I would have thought.

 

[frojoe]

If you still like the action of the torque wrench, have you thought of getting it re-calibrated? There should be a tool calibration place near where you live, and it usually runs $15-$30 per wrench and from what I've seen most wrenches (even the cheapo ones) can be calibrated.

For professional use getting them re-calibrated is a great idea every 6mo to 1 year, but for home use I'd go a couple years. Always store it in the loosest handle (torque) setting to limit the variation in the spring tension thru time, temperature swings, etc.

Of course buying a brand new torque wrench is always sweet too!

 

[TOOL FANATIK]

I would buy a torque wrench that represents what the bulk of what it'll be used for in it's mid to high-range. So yea I'd go 1/4 or 3/8, probably most of your fasteners torque spec is in inch pounds?

 

[wafrederick]

If a cheap foreign made torque wrench,most calibration places won't touch them and this is disclosed too on their website.My Matco tool dealer told me every 5 years to get a torque wrench calibrated.This place won't touch the foreign made torque wrenches and this is the list of the brands they will only calibrate, http://anglerepair.com/brands/

 

[stevenhs]

I would replace it a cheap one like 1/2 TEKTON

http://www.amazon.com/dp/B00C5ZL1NS/?tag=atomicindus08-20

 

[scissorman]

Torque wrenches are most accurate from mid to highest setting but even then there is usually a +/- 2-4% accuracy. I currently own 6 Snap-on torque wrenches, 3/8", 1/2" and 3/4" drive all split beam micrometer type ft/lb. wrenches, then I also have dial type in 1/4" and 3/8" drive in varying ranges for doing more precise measuring of sector shaft preload when rebuilding steering boxes and pinion bearing drag when setting up differentials.

 

[Coach James]

I don't know that I would replace the one you have, but I would get one with a lower range if you do a lot below 30ft-lbs. Years ago, I got one that goes up to 25ft-lbs(I think) for doing bolts on transmissions pans and other low torque items.

Coach

 

[Skin]

Hi, I need some help with the finer details of torque wrenches.

I bought my 1/2" torque wrench probably 15 years ago now and it was rated 10-150lbft, so I thought that'll do me and never thought anymore about it. Recently though I've heard that a torque wrench is only accurate above 20% of its maximum, so above 30lbft for mine. Well that's probably above half of the settings I've ever used it for! So should I buy another, maybe a 3/8" or even a 1/4" one?

Now I'm only a home mechanic, so I guess that torque wrench has been used on average say a dozen times a year for around 15 years as I've not used it for wheel nuts. So should I replace it? I'm not sure how long they last but it's been well looked after. It was never an expensive one so not worth the money to get it recalibrated I would have thought.

That statement is often misunderstood. Its 20% outside of its working range. Basically if you're within 10-150 you're fine. If you try to do 8 foot pounds, or 155 foot pounds, then all bets are off.

 

[MattB77]

Thanks for all your replies.

That statement is often misunderstood. Its 20% outside of its working range. Basically if you're within 10-150 you're fine. If you try to do 8 foot pounds, or 155 foot pounds, then all bets are off.

I hope that you're right but I have seen this 20% of max rule written about quite a bit - I know that doesn't mean it's correct though! Since posting I've had a look at a few torque wrenches for sale and it does seem that the more expensive ones do seem to follow this rule when they quote their ranges, as the cheaper ones will generally give you a larger range like mine.

 

[nuklbstr83]

at work, we have a calibration company come in and do our torque wrenches, meters, measuring tools, etc every 6 months for certification. for a home use only tool, depending on frequency of use, i would just bring it in to a calibration shop once every 12-18 months.

there are several guys at work who have items that are not truck brand items, and they pass calibration tests just as well as the truck brands. our leadman, been there for 41 years owns all craftsman, husky, harbor freight generic brand torque wrenches, measuring tools, etc. and his pass every time. meanwhile last year, my 1/2" SO torque wrench failed. luckily my SO guy is a nice guy and sent it out for rebuild/calibration at no cost.

 

[country83]

That statement is often misunderstood. Its 20% outside of its working range. Basically if you're within 10-150 you're fine. If you try to do 8 foot pounds, or 155 foot pounds, then all bets are off.

Sorry to disagree, but you're wrong. The OP understands it correctly when he says that his 150 ft-lb wrench is only accurate down to 30 ft-lb (20% of full range). Virtually every torque wrench I've ever seen is this way per the manufacturers.

 

[Charles (in GA)]

That statement is often misunderstood. Its 20% outside of its working range. Basically if you're within 10-150 you're fine. If you try to do 8 foot pounds, or 155 foot pounds, then all bets are off.

This is not correct. It is indeed, from 20% of maximum to max. 20% of a 100 lb/ft tool is 20 lb/ft, and 20% of a 150 lb/ft tool is 30 lb/ft. I too did not understand this several years ago, and called a torque wrench manufacturer and talked with an engineer about it. This is the specs established by ANSI and equivalent EU and Australian specs (and others).

The tool might be accurate throughout its marked range, but the ANSI standards don't cover it and the testing (preformed to ANSI standards) won't cover it either, they will only be testing from max down to 20% of max.

NEVER exceed the max of a torque wrench, it may render them inaccurate and damage them to the point that they cannot be adjusted back into calibration. It will destroy a Beam type tool to exceed scale.

Torque wrenches are most accurate from mid to highest setting but even then there is usually a +/- 2-4% accuracy. I currently own 6 Snap-on torque wrenches, 3/8", 1/2" and 3/4" drive all split beam micrometer type ft/lb. wrenches, then I also have dial type in 1/4" and 3/8" drive in varying ranges for doing more precise measuring of sector shaft preload when rebuilding steering boxes and pinion bearing drag when setting up differentials.

Do you have micrometer type? or split beam? or both? they are two very different mechanisms.

I have a mix of everything, this is not all, have added a couple of small beam type since this pic (80 oz/in and 150 lb/in). I have also added a couple of different ratchet heads for the interchangeable head tq wrenches on the front.

 

[guy48065]

^ What he said.
It might be *marked* 10-150--and MAY be dead on--but it's not certified below 30. Period.

 

[BillK]

or split beam?

Charles,
Have you had any issues with your split beam wrenches "sticking" ?? I had two Snap On ones, a 1/2" drive and a 3/8" drive and both of them would stick once in a while and not "click" I use them enough to know when it was happening so as to not over torque a fastener. I would back it off close to the bottom of the range, click it a couple of times and then it would work ok. I sent them both back to Snap On for calibration but still had the problem. I sent the 1/2" drive on back again and when Snap On sent it back, UPS lost it I told my Snap On guy to just give me a micrometer type instead. I retired the 3/8" one to the house and bought another Snap On micrometer to replace it.

 

[Skin]

Sorry to disagree, but you're wrong. The OP understands it correctly when he says that his 150 ft-lb wrench is only accurate down to 30 ft-lb (20% of full range). Virtually every torque wrench I've ever seen is this way per the manufacturers.

Okay, im wrong. Its tested accuracy though, doesn't mean it cant be used through-out its full range. A quality one will still have way better repeatable accuracy through-out its range than that scrap wrench from HF which, much to my chagrin, keeps getting recommended on here despite the fact that it bounces 3-4% between fasteners.

 

[tdkkart]

So if a torque wrench is only accurate at 30 to 150lbs, WTF would they mark it 10-150??

Do I like using them at their lower ranges?? No, not particularly, and I have overlapping wrenches, but I really doubt that any of them are hugely inaccurate in the marked ranges.

 

[country83]

So if a torque wrench is only accurate at 30 to 150lbs, WTF would they mark it 10-150??

I ask myself that question any time I see one marked that way. The only torque wrenches I've seen decently accurate below 20% are electronic ones.

 

[gungatim]

I would add a 3/8" to the mix. I started out with a cheapo 1/2" but wasn't comfortable using it at anything under 50 lbs. so I get the 3/8" out for that stuff. then I added a couple 1/4" ones for small engines. then I got a big 3/4" one but haven't used it yet...then I got a few beam style, and a dial one...like Charles in GA, they can be addicting!