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When I saw this picture of Nick’s antique torque wrench it brought back a few memories; my dad’s old Craftsman model with a black plastic handle looks almost just like this. They’re very cool –- just don’t use one.

I’m not slamming the wrench, or you for having bought one in the first place. They more or less did their job back in the day. It’s just that after 30-50 years of untold bending and fatigue, these old-timers most likely aren’t reading correctly. Unlike a brace or hammer, when a torque wrench loses its accuracy it deserves to be relegated to the show-and-tell portion of the shop. Correct torque is the whole point here — if “close” was all you needed when putting an engine back together then a normal wrench would work fine.

Without fail you’ll hear stories that prove this theory wrong — but the real question is, Would you like to bet your motor on it?   Nick correctly points out that if your only option right now is one of these, it might be worth the money to go get a new one.

A click-type torque wrench will run you around $45 for a low-end one, and you can still get a pointer-type from several sources for about $30.

Toolmonger Photo Pool [Flickr]
Street Pricing [Google Products]
Craftsman Pointer-Type Torque Wrench [Sears]
Craftsman Click-Type Torque Wrench [Sears]

 

14 Responses to Old Torque Wrenches Don’t Measure Up

  1. fred says:

    For a few thousand dollars (maybe more today) you could buy a Teledyne LC-20 torque wrench calibrator – in different ranges – some use to come with NIST certification.

    But then again – just put the old wrench up on the antique tool board as a display and buy a new one.

  2. Chris says:

    I can think of about three reasons that would make an old torque wrench like this read wrong:
    * It’s bent so that parts rub and create friction
    * It’s bent so that it doesn’t read zero at zero torque or doesn’t return to zero after being torqued to full scale a couple times.
    * It’s dented, dinged, or bent so much that length or cross-section is substantially changed.

    If it looks in good shape it should work fine forever. It works on simple physics and the modulus of elasticity (springiness) of steel. The modulus of elasticity doesn’t change much.
    And it’s not hard to spot check it with a fish scale or some known weight and some string.

  3. Electron says:

    Chris is correct. As long as there’s no friction on the indicator or mechanical wear on the beam (gouges, grooves, that sort of thing), a beam-style torque wrench will continue to read accurately. Steel has a very useful property known as a fatigue limit. What this means is that as long as the applied stress is kept below a certain limit, the part can experience an infinite number of stress cycles without degradation. Any beam torque wrench of decent quality will take this into account so that the maximum applied stress is well below the fatigue limit. The deformation a torque wrench experiences is elastic in nature (which is why you see it spring back) and the metal does not “get tired.”

    If you find that the indicator doesn’t rest at the zero point, just bend the indicator far enough that it takes a set (plastically deform it) at the zero point.

  4. jason says:

    I disagree.

    The original style double beam torque wrenches are significantly more accurate than today’s click style.

    No only that, but it’s easy to tell if they’re inaccurate. Their zero is not zero, or the dual leading bars are bent.

    We have plenty of these wrenches floating around our shop, and all of them have to be calibrated every year. Including my vintage 1960’s snap-on dual leading beam style.

    You have to spend a lot of money on today’s wrenches to get one as accurate as the old style (+/- %5 is a lot) find a better one will set you back quite a bit. That’s why we prefer the vintage wrenches here.. and they look great.

  5. Bill says:

    I too have to question the validity of the Sean’s assertions… I agree with Chris, Electron and Jason. If it came down to it, I would bet on an older beam-style being accurate over a clicker, even though I love to use the click style. I see no engineering reason why the beam would lose accuracy over time.

    Not to slam Sean, but where did his information come from?

  6. eschoendorff says:

    And I agree with Chris, Electron, Jason and Bill. What I’d like to know is how Sean came up with this crazy notion to begin with???

    I would be prone to trust a 50 year old beam type torque wrench before a $45 click type torque wrench. In fact, I have used my beam type torque wrenches to double check all my clickers before I’ve used them.

  7. KMR says:

    The problem with beam torque wrenches is their lack of resolution. You can only make the scale so big, and you can only fit so many graduations on that scale, and then it is down to the human eye to interpret the point’s location while the tool is in use. This makes beam type torque wrenches useful for torque specs that are on the low side of the accurate operating scale of a clicker. (If you didn’t know, clickers get more accurate the closer they are to the middle of their rated capacity, and less accurate the further from their mid point).

    The solution? Everyone needs a quality strain gauge based torque wrench in their shop. We bought two at the end of last year, both came with with certified accuracies of better than half of a percent at measurement points across the wrench’s rated range. At its specific calibrated data point (110ft lbs if I recall), it had zero error.

    Right now I grab the old beam type for anything up to about 30 ft lbs. In the 25-250ft lb range, the strain gauge based unit gets used.

    As a side note, our unit of measure for torque (the foot pound) contains every clue you need to build your own accurate torque wrench tester.

  8. Tony says:

    Both my torque wrenches are $15 Harbor Freight click types. I’m probably asking for a disaster.

  9. Shopmonger says:

    The funny part is that both are realtivly accruate enough for most applications and here is why?

    Most (of course) applications of a bolt truly(i mean TRULY) needing tourque to a spec. are under stress and have a heat and cool cycle. unless you are using the same exact steal the bolt is made of in your project. Small micro crystalline structure in the metal will make it cool and heat thus expand and contract at different rates. Thus the excact tourque spec is not as important as getting the bolts to be all the same. Like a head bolt for example, you need to get the head gasket pushed down evenly and tight. So the point being that Consistancy will outweigh Accuracy. And each of these tool are very Consistant unless you leave them in a “Tensial” state. Like the Click style should be backed down each time you put it away.

    I too use both and old style, A newer click style, and a HArbour freight Click. Just be realtistic……

    P.S. to back up Sean, the old ones also can have rust issues, could be left lying not upright (thus leaving stress on the needle) and of course could have been through too many micro heat and cool cycles. Also with metals base structure, metal fatuige also needs to be taken into account……

    No material is for ever………….
    Not even Plastic

  10. l_bilyk says:

    I don’t agree. Beam type torque wrenches rely on the properties of the material they are made of to correctly torque, as opposed to any sort of mechanism. They do not go out of calibration. I bet you that old beam torque wrench is probably more accurate than any clicker that has not been recently calibrated.

  11. Shopmonger says:

    l_bilyk Says:

    I would agree thay new Beam type are very realiable, but again we are talking old…. old will again over a short period of time (say 30-60) days it will be very consistant.

  12. spanky says:

    if you check the warren and brown website they have info about the different type.
    To cut it short the micro click type need regular testing as the spring is under constant tension so can weaken over time while the beam type is not under tension so can last a lot longer. They go on to say they have had 20yr old beam tpye wrench back for testing and they were still accurate.

  13. david says:

    I have a old cal van torque wrench how do. i use it and how do i read it to make sure i am at the right torque capasity

  14. david says:

    I have a old cal van torque wrench how do i read it and how do i know if i am at the. right torque. copasity all it has on it is pound foot and meter kilogram on it

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