The box wrench, and its brother the open-end wrench, are the most common and versatile wrenches. Categorically speaking, a wrench is a tool that fits around a nut (as opposed to inside a screw or bolt, as the screwdriver). Another property of the wrench is that it uses leverage, vis-a-vis the wrench’s handle, to tighten or loosen the nut.
Other types of wrenches include the pipe wrench (for, you guessed it, pipes), socket wrench, adjustable wrench, lug wrench (a box wrench specially designed for changing tires), allen wrench. This last one was placed handily in the screwdriver category, despite the fact that, unlike the screwdriver, it does feature a lateral handle for leverage.
You are likely to need a wrench for:
- Working on a car or bicycle
- Plumbing-related stuff around the house (such as faucets and toilets)
- Objects held together with bolts
As with screwdrivers, it’s important to use the right size wrench. The wrench should fit snugly over the nut, with no play. It’s important to note that there are two sizing systems in all tools: SAE and metric. SAE (which, by most accounts, stands for Society of Automotive Engineers) uses inches. Metric uses millimeters. If you’re working on a classic or older American car, you’re more likely to need an SAE wrench; most late model cars are metric these days. If you’re building a piece of furniture from Ikea, you’re more likely to need a metric wrench. When beginning your tool box, it’s a good idea to get a set of each.
To make it happen, connect the wrench to the nut or bolt, and give it a pull — and yes, it’s best to pull, rather than push. You’ll thank me for this advice if a tough nut or bolt suddenly slips free. While momentum-driven face plants onto uneven metal surfaces may provide hilarious and prize-winning video footage, it’s generally safer and healthier to fall away from metal surfaces.
Open-end wrenches are slightly angled. For best stability, angle your open-end wrench so that the more-open side is closest to you (or closest to the direction you’re pulling). Same goes with adjustable wrenches: the stable (and solid) side should be away from the direction you’re pulling, while the adjustable side is closest.
One more thing to consider is the angle of the wrench arm itself, giving yourself the best leverage. When possible, place the wrench at a 90-degree angle parallel to your body, so that pulling the wrench straight toward you allows for maximum torque. Once it’s loose, and less brute strength is needed, you can go for the wrench’s full range of motion.
Here’s a neat little trick, if the nut is stuck. You can use a length of metal pipe to extend the handle of the wrench. The longer the handle, the more torque leverage you get. That’s a fancy way of saying it will turn more easily with less work.
If a nut or bolt is really stuck, try a quick spray of Liquid Wrench or silicone directly onto the threads. Avoid using too much of this lubricant — you want it on the threads, not on the ears of your nut or bolt.
One more use of a wrench is to hold one end in place. Fasteners often consist of a bolt and a nut. You may try turning the nut, but instead of tightening, the bolt turns with the nut. In this case, you may need another wrench — one to hold the bolt in place, the other to turn the nut. If the item in question was designed properly, the nut and bolt will be two different sizes, so you can use two wrenches from the same set.
If you use the wrong size, or an “approximate” size (i.e. using an American wrench to tighten a metric nut), you can strip or “dog-ear” the nut, making it unusable. For this reason, avoid using an adjustable wrench when you have the right sized box or open-end wrench for the job.
In some situations you may not have enough room for the full swing of a wrench. In such cases, dig back into your toolbox for the next tool in our series…