Calibrating Torque Wrenchs How To

But there is more to understanding whether your torque readings are accurate. The torque wrench only measures how much rotational force it takes to turn the fastener, not the clamping load itself. So the torque wrench will only achieve the clamping load you expect if you are turning a fastener under the conditions that the manufacturer assumed when setting the torque specification. In general, the amount of friction depends on multiple factors including surface coatings, temperature, materials, and fastener shape and size. If those factors vary unexpectedly, you may get unintended results that are outside the calibrated accuracy range of the torque wrench.

1. Look carefully. You have to set the torque wrench with your own eyes. If you accidentally set the dial at 98 or 102 when you mean to set it at 100, you have introduced extra error. This can happen if you are looking at the scale at an angle.