Torque wrenches are awesome. Seriously. Using them not only lets you know that the bolt you’re tightening is probably going to stay tight, but that you’re not likely to snap its head off. Using a torque wrench religiously has probably saved me way more time and headaches than anything else in my toolbox, but how does it work? Specifically, how does a click-style torque wrench work and how should I go about using it and storing it to make sure it stays accurate?
As to how it works, there’s a rad video from YouTube channel Deconstructed that does a great job of explaining how the wrench translates spring tension and a pivot block into an accurate torque. It’s surprisingly simple and knowing what’s inside these types of torque wrenches leads us into our next topic: how to use and store your click-type torque wrench.
The “how to use” part is pretty easy. You set your desired torque with the handle, and then as smoothly as possible (i.e. not in a jerking motion) you rotate the wrench in the direction that will tighten your fastener. Once you get to your set torque, the wrench will audibly click, and bingo! You’re done. Most people like to click the wrench a couple of times because the sound is just so dang satisfying, but this can adversely affect your fastener’s torque, so if you’re doing a particularly sensitive job, it will make a difference.
Where you hold your torque wrench makes a big difference in how accurate it is. Grip the wrench on the designated handle portion and rotate from there. You can also use a second hand to put downward pressure on the fastener to make sure your tool doesn’t slip off. Don’t grip the tool higher up than the handle because this will dramatically change the torque at which the wrench clicks. Also, despite what you might have heard, using socket extensions with a torque wrench is totally fine and won’t change your results.
The other no-no is using a torque wrench to bust a fastener loose. This can put a whole bunch of stress on the finely calibrated click mechanism and cause your wrench to go out of spec sooner than it normally would if you do it a lot. Use a breaker bar or a regular ratchet for this, or you could even use the big, expensive electric impact you got on sale at the home supply store. Go wild.
Storing your torque wrench requires a little extra care than you might expect, too. Some wrenches will have the setting at which they’re designed to be stored engraved on them. For example, the 3/8-inch torque wrench I just bought from the jungle website says to store it at 10 pound-feet. My 1/2-inch wrench doesn’t say anything, so I store it with no tension.
The reason this is important is that leaving the wrench wound up to, say, 96 pound-feet for lug nuts and then throwing it in your toolbox for months can cause the spring inside to wear and become weaker. The accuracy of the wrench is predicated entirely by the specific resistance the spring was designed to provide from the factory. Also, if your wrench came in a blow-molded case, store it in there. It will help keep it from being knocked around, though that’s mostly to keep it looking pretty.
Following these guidelines should help keep even a reasonably cheap wrench accurate for years, if not decades, so good luck and happy wrenching.
