with "normal" tools? Is there a method that works? Or do you have to bring it in to a calibration shop?
Maybe I'm wrong but I thought the OP asked how to calibrate a torque wrench, not how to use one. :dunno:Ok sorry little sour some times here, anyway some real info ..... don't drop it, one click and stop and never.use it to remove stuff
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Snap On wrench is good, HF wrench isn't. That is Bluebee's fundamental problem.Just pointing out that if u don't drop it and u use it correct u will not have to calibrate it, I've used the same snap on,torque wrench for years and years , one of my clearest tools still looks like new
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The method in the link a few post above uses a long lever arm, about 7-8 feet and a gallon of water, which is a precise load , and more accurate than a fish scale. Fish scales are cheap and their accuracy is quite poor.BB
Your KISS method should work fine as one wrench simply resists the torque of the other. However, most torque wrenches, including the HF torque wrenches that I have, have rotating adjustment scales. Using this method, you can compare two wrenches but you cannot calculate how much out-of-calibration your torque wrench actually is.
I came up with a much simpler method to home-calibrate your torque wrench. It requires a spring scale that measures pounds, up to at least 50 lbs (which every respectable big fish flyfisherman should have). Larger is better, especially when you try to calibrate the 1/2" torque wrenches. Take your torque wrench and set it to say 10 ft-pounds. Find a nut or bolt that is torqued way above that value and the axis is set vertically, to eliminate the weight of the wrench from the calculation (the torque wrench should be horizontal). Place the scale hook at the hand application point on the torque wrench. Measure that distance from the socket axis (inches). Pull on the scale and take a reading when it clicks. Do this a number of times to get a mean average force (lb). Multiple by the distance (inches) and divide by 12 to get ft-lbs of torque. The difference is how much out of calibration your torque wrench is. Repeat at the next setting (20 ft-lb) and on up the range until you know how close your torque wrench is across the complete range of settings.
NOTE: Tha accuracy of this calibration technique is only as accurate as the scale used. If your scale has an inaccuacy of +/- 3 lbs, that inaccuracy gets multiplied by the length of the lever arm.
are you suggesting a HF torque wrench is to be used on anything, but maybe the lug bolts on an E39? :dunno:Your personal problem with BB is showing here and in past threads.
My buddy and I politely asked a Costco tire center to check our torque wrenches, as every one of them has a torque calibration tool. They check their wrenches monthly and log the results. They CANNOT, fix or adjust the wrench, only determine if they are in calibration or not. (bring donuts, or other savory item, when they are not busy ). The results were his two practically brand new Craftsman wrench were both out of spec, and my 20 year old Utica wrench was right on the money. http://www.cooperpowertools.com/brands/torque/index.cfmGreat tips. The link from the 2nd post is great. Also Fudman's idea is great.
I am asking, because I want to be sure my torque wrenches are in spec, and I don't want to waste $$ sending the wrenches to calibration shops when there is no need to (I hope). My wrenches are always taken care of, not banged. They are always reset to "0". My only concern is they rest in my garage which is cold, and the temperature swing from summer to winter and back to summer is significant where I live.
I am not sure if this will affect the calibration or not, but I want to somehow check this, so I am sure I have the correct setting, especially when I deal with the small bolts/torque wrench which is using the in-lbs scale...
These are the key ingredients right here: quality tools. That's what I have and I sunk a considerably chunk of money in my tools hoping they will last. Great piece of info, which is peace of mind for me. Thanks.My buddy and I politely asked a Costco tire center to check our torque wrenches, as every one of them has a torque calibration tool. They check their wrenches monthly and log the results. They CANNOT, fix or adjust the wrench, only determine if they are in calibration or not. (bring donuts, or other savory item, when they are not busy ). The results were his two practically brand new Craftsman wrench were both out of spec, and my 20 year old Utica wrench was right on the money. http://www.cooperpowertools.com/brands/torque/index.cfm
Even if you have to pay a calibration shop to check your wrenches and adjust them, it is not terribly expensive, and not something that would need to be done more than every few years once you start from a known point. From some checking I have done, it is typically around $35 to check, and another $35 or so for adjustment with calibration certificate.