Torque Wrench

TrickyWicky

molerat wrote: »

How do you know that any torque wrench is accurate ? I have seen incredibly expensive ones that are way out.

How do you know this? - Do you have special testing equipment to test the torque of the nuts / bolts? (Please don't say you tried undoing them with the TW as that can destroy them).

londonTiger wrote: »

all torque wrenches have high tolerare at the low end of torques. That's why for engine head work you need a small TW geared towards lighter torques like 5nm to 30nm.

I assume thats aimed at the previous poster? - I kind of know that (remember I've been advising YOU!). Also a low range TW is not useful for cylinder heads. Typically you'll need in the 50 - 60 Nm range not 5 to 30 (which is very low when you consider the cylinders have thousands of explosions inside them with every trip). The head must be fastened down very strongly. Maybe you've got Nm and daN.m muddled up? - da stands for deca (see wiki) which means you multiply the number by ten. Just to clarify by "head work" I'm thinking head bolts that hold the cylinder head to the block - it's possible you're thinking of something else so if my wires are crossed, apologies in advance.

If you're talking about things like the rocker cover then the bolts for that probably are in the lower range unlike the head bolts.

londonTiger wrote: »

I want to it gear oil drain/fill plug tighteining. I'm just going to do this up using guesswork and then properly tightening the holes using a working torque wrench next time.

As I've said, for engine work you need a better TW than a nasty cheapo. Personally for a sump plug it isn't worth it. Just do it by hand and trust your instinct. It's not a perfectly engineered surface with multiple bolts that must all be the same like the cylinder head. The sump plug is just one bolt by itself. The engine heat will help it to stiffen up anyway - thats why you only do oil filters hand tight and then need a tool to get the damn things back off again lol.

Like I said, save your money up and get a proper TW

cyclonebri1

If you are hell bent on doing some car work this weekend then go to a shop/market etc and buy one, your money is/has been refunded so what's the problem.

If you want a fool proof one you can still get the old type that has no moving parts, simply a spring arm that is read off against a graduated quadrant, all done by the deflection in the torque wrench itself. I still remember 1 of my old mates saying he couldn't get 1 of those to click:rotfl::rotfl::rotfl:

colino

Do you still get the wavey arm torque wrenches? Worse than useless with users looking at them from all sorts of angles and thinking they have the same torque applied!

Inner_Zone

colino wrote: »

Do you still get the wavey arm torque wrenches? Worse than useless with users looking at them from all sorts of angles and thinking they have the same torque applied!

Yes still available, had one thirty years ago, was next to useless:

http://www.drapertools.com/b2c/b2citmdsp.pgm?pp_skmno=34487&ipadd=

soon replaced with a 1/2" Sykes-Pickavan which I still have and a 3/8" Britool one which I no longer have..

And Halfords have one at a premium price too:

http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_919431_langId_-1_categoryId_242558

colino

Amazed at the price of that rubbish, I've still got my original Norbar Click Stop 1/2" drive that cost around £15 (correct that, nostalgia kicking in, it was a fortune for me as that was about 30+ years ago). Checked twice in its life for calibration, never been re-set as it's still spot on.
Don't buy a cheap one and don't bother with ultra low torque ones. If you need one at low levels, you probably shouldn't be fiddling with it in the first place.

Wig

londonTiger wrote: »

it's a ratchet type torque wrench so it is compeltely loose one direction, and [supposed to] apply force the other direction up to the set torques. So this isn't an issue. If I had it the wrong way round - the torque wrench would just spin down and become vertical, let alone pick up the weight.

Hmmm, no, it has a reversible ratchet but not a reversible torque, so if the ratchet was set to "undo" and you picked it up the wrong way....there would be no click no matter what force you applied. So you should have logically checked with the ratchet set to each direction.

Yours does not have an anticlockwise torque so point 'B' of my checklist would not apply. My TW clicks in one direction but is solid in the other direction, and it is reversible for anticlockwose torques. The advantage of this design is that you can't break the ratchet.
http://www.amazon.co.uk/Britool-EVT1200A-2-inch-Torque-Wrench/dp/B004ZFCIG0/ref=sr_1_3?s=diy&ie=UTF8&qid=1361614085&sr=1-3

I personally wouldn't like the Machine Mart one you linked to earlier as it doesn't have a Nm scale.

There is this one - out of your price range & the scale looks a bit small & innaccurate to me.
http://www.amazon.co.uk/Norbar-TruTorque-certificate-calibration-England/dp/B002BIV0AS/ref=sr_1_598?s=diy&ie=UTF8&qid=1361615434&sr=1-598

I guess I'm going to have to say as you want cheap, and you can't get a cheap one with spring lever like mine....And I would recomend one with a 1/2" and a Nm scale, and a max of about 120Nm...I could not find one that matched all criteria, so having to compromise on something, I would compromise on Max torque.
I came up with this one or the Lidl one if it's still available
http://www.amazon.co.uk/Silverline-633567-Torque-Wrench/dp/B000LFTSG6/ref=sr_1_1?s=diy&ie=UTF8&qid=1361614574&sr=1-1
And I would just say that you should calibrate it yourself, make a written conversion table of indicated torque to actual torque using that youtube video.....however, he doesn't account for the turning force due to the weight of the TW, which if I'm not mistaken, would not simply be the weight of the TW.

Wig

colino wrote: »

and don't bother with ultra low torque ones. If you need one at low levels, you probably shouldn't be fiddling with it in the first place.

Disagree, smaller torques 8 - 30Nm are found all over a vehicle, and a small TW will be smaller in size and will be easier to use inside a wheel arch or down inside an engine bay and you will have more accuracy than using a large TW set to a low setting..

If you are -as you seem to be- saying that you can just guess for low levels, well yes you can, but it's nice to have the right tool for the job and know that it is right, first time, everytime.

molerat

TrickyWicky wrote: »

How do you know this? - Do you have special testing equipment to test the torque of the nuts / bolts?

Is the correct answer, checking the torque wrench on a calibrated test rig before every use.

cyclonebri1

colino wrote: »

Do you still get the wavey arm torque wrenches? Worse than useless with users looking at them from all sorts of angles and thinking they have the same torque applied!

Yes that's what I was on about, guy brought 1 to me asking why it didn't click when you put some torque on it.

They weren't that bad but as said you had to view it square on and it wasn't difficult to bend the darn things.


Calibrating a torque wrench before every use?, No. And if we are being really pedantic you should actually check it after every use to ensure if it went out of calibration during use you could re torque to the correct figure.

But lets face it, we aren't NASA spaceship engineers, it's a darn Fiat or such like, near enough with the cheapest uncalibrated torque wrench will be good enough.

Don't forget to use that uncalibrated Mk 1 brain, that'll tell you if it's roughly correct, :rotfl::rotfl:

londonTiger

Wig wrote: »

Hmmm, no, it has a reversible ratchet but not a reversible torque, so if the ratchet was set to "undo" and you picked it up the wrong way....there would be no click no matter what force you applied. So you should have logically checked with the ratchet set to each direction.

Yours does not have an anticlockwise torque so point 'B' of my checklist would not apply. My TW clicks in one direction but is solid in the other direction, and it is reversible for anticlockwose torques. The advantage of this design is that you can't break the ratchet.
http://www.amazon.co.uk/Britool-EVT1200A-2-inch-Torque-Wrench/dp/B004ZFCIG0/ref=sr_1_3?s=diy&ie=UTF8&qid=1361614085&sr=1-3

Thanks for pointing that out to me, although I feel a bit of a numpty going on my earlier tirade - I feel glad I posted the message earlier Because I was inded trying to torque it backwards when I did my initial test.

I have retested it and to be fair it's performed pretty well and I'm going to keep it. Posted the results.



TW not faulty and has a acceptable degree of accuracy for it's cost.

p.s. on the other hand barbell weights are really dodgy.

The test corroborates the torque wrench test certificate - i.e. torque is correct to 4% and in this case it takes a little less torques than stated to make it click

Torque wrench test certificate:
16nm test load = 15.86 (average reading)
48nm test load = 46.18 (average reading)
80nm test load = 80.96 (average reading)