Torque wrench- how do you know it's accurate ??

[HughJarse]

Changed the front discs on car...( relatively easy once I'd watched the nut and bolt trick to remove the discs) then torqued wheel nuts back on with wheels attached obviously.

My question is, how do I know my torque wrench is accurate - I haven't used it for a few years so it could be well out?????

 

[C36fan]

Changed the front discs on car...( relatively easy once I'd watched the nut and bolt trick to remove the discs) then torqued wheel nuts back on with wheels attached obviously.

My question is, how do I know my torque wrench is accurate - I haven't used it for a few years so it could be well out?????

You don't until you get it tested.

 

[WDB124066]

They are VERY susceptible to error. I've tested numerous wrenches and they drift like you would not believe, often seriously. I will not let shops use them unless they have been at least checked against a known accurate one back to back in a vice - which is a good way for a quick check by the way.

 

[brucemillar]

I am guessing that you try and calibrate it using a spring gauge and a vice. Or do what the tyre shops do and don't bother ;ˆ)

 

[Norte23]

The tyre shop do it 20 dackadacks on the impact gun don't they. Hahahaha

Mark

 

[brucemillar]

I have an impact gun. And even on my fairly breathless 100psi (that could be a lie) compressor the dackadacks do it up fairly tight. Fairly tight is an accepted measure of tightness as is football pitches for length or people in a telephone box for capacity.

 

[KennyN]

As stated , you dont until properly tested but leaving them for any length of time with any load on the spring will cause inaccuracy.

How accurate your was to start with is anyones guess but as with most things the price is normally a good indication of quality and accuracy, but if it is only used once in a blue moon then why spend the bucks on a really expensive one.

Every year we just buy new wrenches all of which come with a 12 months calibration certificate which is good enough for our annual audit .After the first year is past we just bin them and get new ones as testing them by an outside company is almost as expensive as buying new ones.

Kenny

 

[Will]

Funny enough I have two - a cheap spring/click type one I've had for years (can't even remember the brand) and a digital snap-on one that also does angles and stuff.

Surprisingly the cheaper one is also very accurate. I think people either abuse them or leave them wound up which doesn't help. I checked the cheap one against an engineering shop in the range of approx 20-100Nm and it was spot on.

Even if yours was a little out, at least the bolts will be evenly torqued (!)

 

[WDB124066]

As stated , you dont until properly tested but leaving them for any length of time with any load on the spring will cause inaccuracy.

How accurate your was to start with is anyones guess but as with most things the price is normally a good indication of quality and accuracy, but if it is only used once in a blue moon then why spend the bucks on a really expensive one.

Every year we just buy new wrenches all of which come with a 12 months calibration certificate which is good enough for our annual audit .After the first year is past we just bin them and get new ones as testing them by an outside company is almost as expensive as buying new ones.

Kenny

You can buy a torque wrench tester and do the checks and adjustments yourself, we were faced with the same problem as you, it was an economic option for us -but many of ours are large and very expensive to purchase regularly.

 

[markjay]

Good quality wrench will come with certificate of calibration. On one occasion I had some doubts regarding the accuracy of a new torque wrench so sent it back to manufacturer who recalibrated it and tested it under warranty.

 

[markjay]

And yes you should always fully relax the spring when the wrench is not in use.

 

[Rory]

Isn't using torque for nuts and bolts a very inaccurate process anyway?

 

[HughJarse]

Given that I didn't know you had to undo the wrench when you put it away, it must be well out. To be honest, I got it out as the bolts on the brakes needed a longer wrench for leverage and this is my longest wrench... I then decided I might as well use it to tighten nuts - think they were 130 from memory.

Ok then - without a torque wrench - what would be an acceptable tightening procedure for wheel nuts in alloy wheels?
Im sure Ive read that it's easy to overdo them. I guess you immediately have the inaccuracy of how strong the person tightening them is?

I also bought for about £3 an adapter that lets me attach a wrench end to my battery drill - made whizzing the nuts in Sooooo much easier ( put it on loosest setting so it clicked as soon as they were in - not tight)

 

[markjay]

As a lad we only used Torque wrench on head bolts, and even that what a round scale gauge with a pointer.

Everything else was done by 'feel' including wheel bolts.

Spark plugs? If they had a collapsible seal, then tighten until you feel resistance (seal pressing against cylinder head), then another 1/4 turn for new plugs, or 1/8 for re-used plugs.

Everything else depending on material (plastic, allow, steel) and location (suspension bolts are done tightest etc ).

And yet these days I would always prefer to use a torque wrench where I can. The old ways worked and they were OK, but the new ones are better.

 

[alzieboy]

I always thought/ told to store torque wrench at its lowest setting

 

[KennyN]

You can buy a torque wrench tester and do the checks and adjustments yourself, we were faced with the same problem as you, it was an economic option for us -but many of ours are large and very expensive to purchase regularly.

The problem for us is that the annual auditors want pukka certificates when they check our calibration register which is a PITA as half our neanderthal guys wouldnt know a torque from a hammer and most wrenches have the dents to back that up.

Isn't using torque for nuts and bolts a very inaccurate process anyway?

Possibly but it is the only standardish way of tightening fasteners up.

Ok then - without a torque wrench - what would be an acceptable tightening procedure for wheel nuts in alloy wheels

There isnt as your tight will not be the same as anyone elses tight , especially on softish alloy.

I always thought/ told to store torque wrench at its lowest setting

Normally you can back the spring off lower than the 0 setting.

Kenny

 

[190]

As a lad we only used Torque wrench on head bolts, and even that what a round scale gauge with a pointer.

Everything else was done by 'feel' including wheel bolts.

Spark plugs? If they had a collapsible seal, then tighten until you feel resistance (seal pressing against cylinder head), then another 1/4 turn for new plugs, or 1/8 for re-used plugs.

Everything else depending on material (plastic, allow, steel) and location (suspension bolts are done tightest etc ).

And yet these days I would always prefer to use a torque wrench where I can. The old ways worked and they were OK, but the new ones are better.

I was the same, did everything by feel except for bearing caps and head bolts. I did a complete engine overhaul using one of those beam type torque wrenches because they were cheap. These days clickers are cheap too so anyone can afford one.

I don't believe I've stripped a thread in over 45 years possibly assisted in the early years by by the fact that things were not so fragile back then. I only got serious about clicker torque wrenches with motorcycles which have a lot of alloy threads.

To do a rough check on calibration fasten the square drive in a vice and hang weights from a measured point on the handle...but make sure to have the weights calibrated first !

 

[area51]

The torque wrenches that we use at work are all preset to the relevant torque required. Leaving an adjustable torque wrench wound up doesn't always alter its calibration.

Some worthwhile reading here: http://www.norbar.com/en-gb/News-Events/Blog/entryid/428/Default

 

[WDB124066]

Kenny it only has to be traceable to National Standard, the reference instrument you buy will be and all you are doing is comparing your wrenches to an instrument directly traceable to National Standard.

Auditors do get excited at times because they just do not know their job so they make things up.

 

[KennyN]

Kenny it only has to be traceable to National Standard, the reference instrument you buy will be and all you are doing is comparing your wrenches to an instrument directly traceable to National Standard.

Auditors do get excited at times because they just do not know their job so they make things up.

I will have a chat with the chief engineer later today regarding the above but our company seem to go heavily into the paperwork side of things and have paperwork trails like you would not believe. On the plus side everyone now has a torque wrench (or two) at home due to their continual replacement over the years

IIRC we have around 5 wrenches within the department so forking out £200 every year on new wrenches isnt the end of the world considering the wastage elsewhere within the building.

Got to agree about the auditors as some of the questions they ask during their visit beggar belief and shows a serious lack of knowledge regarding engineering matters.

Kenny