Any wrench = a torque wrench

Discussion in 'Tools' started by Wuzzat?, Dec 5, 2012.

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  1. Dec 5, 2012 #1

    Wuzzat?

    Wuzzat?

    Wuzzat?

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    I needed to adjust a timing belt tensioner to 33 lb-ft and there was no way my torque wrench would fit into the space available so I got two stiff springs from HD.

    Filling a 5 gal bucket with water (2 lbs for the bucket + [5 gals x 8.3 lbs/gal]) = 43.5 lbs and stretched the spring 1.09" from its rest length so the spring constant K = 40 lbs/inch.

    The spring was anchored on the wrench handle 7" from the center of the 3/8" drive stub so 33 lb-ft would need a right angle force of 33x12/7 = 57 lbs.

    As it turned out the posted max force on the spring was 61 lbs (no max length given) so it was close. I should have done this calc. before I bought the thing but it worked out.
    And with two springs in a package for $4 I could in principle go to 66 lb-ft or so.

    Next is to check the K for my weaker springs from the basement.
     
  2. Dec 5, 2012 #2

    nealtw

    nealtw

    nealtw

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    like this?

    fish scale.jpg
     
  3. Dec 6, 2012 #3

    oldognewtrick

    oldognewtrick

    oldognewtrick

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    Why don't you just go to the local parts store, most have tools they will rent or loan out.
     
  4. Dec 6, 2012 #4

    Wuzzat?

    Wuzzat?

    Wuzzat?

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    It turns out that this wrench must have magical properties, because after I used it the car started and ran more smoothly than before. :D

    Man, am I glad I can finally move this car out of the driveway! :rolleyes:

    I figure one hour round trip to the rental place, twice, so I calculate, "Can I make the part/tool/fixture in less time?"
    This one was close.
     
  5. Dec 6, 2012 #5

    nealtw

    nealtw

    nealtw

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    When I was young and couldn't afford such luxury as a torque wrench, I and all my back yard machanic friends had a fish scale in the tool box. If you notice a set of combination wrenches all have a different length. If you use one of these and give it a reasonable pull, you will be really close on the required torque for that size of bolt. The reason they give you a required torque is because an impact wrench can dammage aluminium parts you are bolting into.
     
  6. Dec 7, 2012 #6

    Wuzzat?

    Wuzzat?

    Wuzzat?

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