It’s been three years since the last post, but welcome back to our Toolmanship series! The goal of this series is to teach the very basics of tool use to those men who never got around to learning how to be handy when they were growing up.
In this edition, we turn our attention to wrenches (or spanners for our readers who use British English). They’re an essential tool to have in your toolbox and are used to tighten and loosen nuts, bolts, screws, and pipes. Below we’ll take a look at the most common kinds of wrenches and how to use them.
General Wrench Use Guidelines
Select the right wrench size for the job. To avoid damaging your fastener or yourself, always select a wrench jaw size that corresponds to the fastener you’re tightening or loosening. Also, make sure your wrench’s jaw is in complete contact with the fastener before applying pressure. These two things will go a long way in preventing your wrench from slipping and you swearing about a bruised knuckle.
Pull, don’t push. When using a wrench, you typically want to position yourself so that you pull it instead of push it. This ensures you don’t bark a knuckle whenever the wrench slips off the fastener. If you do need to push a wrench, use the heel of your hand, that way if the wrench slips, you won’t hurt yourself.
Don’t add more leverage with pipe. You may have seen your dad put a longer piece of pipe over his wrench to gain more leverage when tightening a fastener. You should avoid using “cheater bars” for several reasons. First, they can damage your wrench by bending the handle or jacking up the head. Second, because of the added torque you get with the extra leverage, you risk rounding your fastener if you don’t have the right wrench head for the job. Finally, there’s a chance the cheater bar will slip off the wrench’s handle while you’re turning, causing harm to you or others. If you need more leverage, use a longer wrench. If you have a particularly stubborn fastener, apply some penetrating oil (like Liquid Wrench) to the thread, wait a few minutes, and then try loosening.
Don’t hit a wrench with a hammer. Unless you have a special “strike face” wrench that’s designed for being hit with an object, don’t take a hammer to your wrench in order to get more power to turn a stubborn fastener. You risk damaging your wrench.
Don’t use a damaged wrench. If the handle is bent or the jaws look wider than they're supposed to be, don’t use it.
Buy quality wrenches. Good wrenches last longer; cheap wrenches slip more easily. Personally, I'm a Craftsman fan. They've got a lifetime warranty on all their hand tools. If a wrench ever bends or breaks, you can take into a Sears or Ace and they'll replace it for free, no questions asked (some sales associates might give you guff). I don’t have any affiliation with Craftsman whatsoever — it’s just what I use.
Types of Wrenches and How to Use Them
Adjustable Wrench aka “Crescent Wrench”
This should be your first wrench you buy if you’re just starting your tool collection — one big and one small. An adjustable wrench has one fixed jaw and one adjustable jaw which allows you to use it on a wide variety of fastener sizes. The jaws are typically smooth and flat and designed for gripping square and hex nuts. The head of a crescent wrench is usually angled at 22 1/2 degrees to the handle so that the wrench can be flipped over to provide two different gripping positions in tight spaces.
How to Use a Crescent Wrench
While a crescent wrench is designed so that you can apply pressure on both the fixed and movable jaws, ideally the bulk of your work should be done so that pressure is only applied on the stronger, fixed jaw. Too much pressure on the weaker, adjustable jaw can cause the wrench to break and you to bark a knuckle. When placing the wrench on your nut, the adjustable jaw should be located on the side towards which the rotation is to be performed. This puts the pressure on the fixed jaw. Below is a nice little illustration showcasing this method:
Also, when you place your crescent on a bolt or nut, make sure the adjustable jaw is snugly adjusted to the nut or bolt in order to prevent the wrench from slipping and rounding the nut or bolt.
An open wrench is a nonadjustable wrench that comes in a variety of sizes. You usually buy them in sets (in both metric and standard SAE sizes), though you can buy them individually if you want. There are a few advantages that open wrenches offer over adjustable wrenches. First, because both jaws are fixed, you don’t have to worry about breaking an adjustable jaw. Second, they’re really handy to have when you’re tightening and loosening a bunch of nuts and bolts of the same size because you don’t have to readjust anything whenever you put wrench to bolt. Makes tightening and loosening much faster than with an adjustable wrench.
How to Use an Open Wrench
Select the right size open wrench for the nut or bolt you’re loosening or tightening. Reposition the wrench on the fastener after each turn.
A box wrench has an enclosed opening that looks like a ring. The enclosed opening minimizes the risk of damaging your fastener. This kind of wench is typically used on heavy-duty jobs. Box wrenches usually have a six-point or twelve-point recess and are best used on hex-head fasteners. The twelve-point recess allows you to change the position of the wrench on the nut with only a small handle movement. Some box wrenches have an offset handle which allows for knuckle clearance over obstructions on a flat surface. You’ll also find box wrenches with a ratcheting mechanism which allows for more efficient tightening and loosening.
How to Use a Box Wrench
Not much to it. Select the right size opening for the nut or bolt and start tightening or loosening. Reposition the wrench on the fastener after each turn.
You’ll typically find open and box wrenches on the same tool in the form of a combination wrench. One end will be the open-end wrench; the other end is the box wrench. Both ends generally fit the same size nut and bolt.