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Torque Wrench Graph

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This graph shows three tests of a Harbor Freight 1⁄2-inch clicker torque wrench that Cornerstone performed over a period of 60 days. Test 1 is the original test that shows the wrench varied between 69 and 70.3 lb-ft. Test 2 shows what happened to accuracy after leaving the wrench at the 70 ft-lb setting for 30 days. Notice how the curve retains its repeatability, but is down an average of 2.6 lb-ft. Test 3 is the same wrench after 60 days. Note how the spring in the wrench has relaxed, which has not only leveled out the testing, but reduced its accuracy down to an average loss of 4.4 lb-ft. As the chart shows, the wrench now torques to roughly 65.5 with a setting of 70 lb-ft. If the wrench were left for longer, the actual torque would continue to drop.

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