The bolt has always gotten the glory, but the nut is the real star. It can be round or square, winged or crenellated, easy to remove or impossible to remove. Around since the 15th century, it’s been adapted for hundreds of applications. It holds together everything from bridges to bicycles. It holds our world together. These are its most remarkable versions.
The nut that secures the trap under your sink. Makes cleaning it out a breeze. Although we’re hesitant to tell people to remove any nut with a pair of pliers, this one is designed to be loosened or tightened with pliers or an adjustable wrench. Like all threaded plumbing fittings, a slip-joint nut shouldn’t be overtightened, particularly if it’s made out of plastic. When you buy one of these in a little plastic pouch, you may see an abbreviation on it TPFT 1.5, or something like it. It means tighten the fitting with a plier or a wrench “one and a half turns past finger tight.” So always run up the slip-joint nut by hand until tight. Then use pliers or a wrench to bring it to full tightness, making one to two more complete revolutions, but no more.
Seems purely decorative, but it's designed to accept a cotter pin for locking it in place. The pin passes through a hole in the bolt, through the slot in the nut and then each half of the pin is bent around in the nut in opposite directions. It’s a beautiful, simple design that locks the fastener in place after it has been properly tightened. Now, there are other methods to lock a nut in place, such as proprietary adhesives and nuts with nylon inserts, but the castellated nut (also called a castle nut) is still king for many applications, especially ones where a technician might need a quick visual cue that the nut has been locked in place. A missing cotter pin will signify that something may be amiss.
There are several good reasons to use a flange nut, which comes with a built-in washer. First, is convenience. By eliminating the washer under the nut, you have one less part to lose or worry about. But second is tightness. When you use a nut with a washer, you create two bearing surfaces: one between the nut and the washer and one between the washer and the bolting surface. No big deal, right? Wrong. For mission-critical bolted assemblies, that extra bearing surface can be an opportunity of one metal surface to wear against the other, resulting in loosening of the nut. Use a flange nut, especially a high-quality one, and you cut the number of bearing surfaces in half and increase the odds that the nut stays tight. And the final case for using a flange nut is that the sturdy flange helps support the first couple of threads in the nut, creating a unified assembly as the nut is tightened. Again, this helps the nut stay put, which is exactly what you want.
A nut with flair. Great for hard-to-reach areas. These look great and work well for applications where the nut will have to be loosened frequently. Most of these are cast, but heavy-duty versions are forged for the last word in strength and impact resistance. There are a number of applications where you need such a sophisticated fastener. Suppose you build something that requires rapid assembly and disassembly. Suppose also there are times when the nut and bolt will be separated by an awkward obstruction. Reaching around to grab that nut with a wrench might be difficult. But with a handle nut, you hold the nut in place, slip the bolt through and tighten the bolt while holding on to the handle nut’s handle.
The cap protects you from scraping against the thread. The nut that looks out for you. It’s a perfect decorative choice and chrome varieties add that extra “trick” quality to a project as do “high crown” types with a tall, oval dome. The cap nut not only protects us against the exposed bolt, it also covers the bolt end, protecting it from damage, corrosion, paint and countless other substances that can foul the threads and make the nut difficult to remove.
Old-school and, unlike a six-sided nut, it has a longer bearing surface for the wrench jaw to bear on. The downside of the centuries-old design is a lack of access to its flat surface for removal and tightening. Furthermore, only an open-end wrench, an adjustable wrench or an eight-point socket works on these.
You can only put them on or take them off with a tool called a trident socket or a tri-groove socket. No, you won’t find those at the local hardware store. This is a good choice if you’re trying to keep your kids from disassembling something, but also deter people with more nefarious intentions. Thieves have been known to unbolt stuff when defeated by a lock. A tamper-resistant nut provides an extra measure of security.
Wildcard! Strip the ends of the wire; line them up parallel and twist on one of these guys to get a safe, secure electrical connection. Just be sure to use the right size for the wires you’re connecting, otherwise you risk a fire. And the right size is determined by the manufacturer who lists that data on the wire connector package. Although all of these products are often called informally wire nuts, that’s actually incorrect. Wire Nut is the connector that pioneered this category. It’s a trademark term owned by Ideal Industries.
Stamped sheet steel wing nuts, called Ds in the wing nut trade, are the cheapest. Cold-forged, usually stainless steel, called Type A, are stronger and better looking. When you’re not tightening these nuts by hand, say you need a pair of pliers, be careful. Inexpensive cast versions can suddenly snap off when you apply just a bit too much force. And never tighten any version of this by tapping on the wing with a hammer. That’s a quick route to an over-tighten or damaged fastener.
You say to someone, “Name a nut” and they’ll blurt out “Hex nut!” Like bolts, hex nuts are made from a variety of materials, such as plain carbon steel and brass and they may be plated or have a plain steel finish. Their strength varies accordingly. A garden variety nut may withstand tens of thousands of pounds of force but high-strength varieties may withstand a tensile (pulling) force well over 100,000 pounds. That’s a pretty strong nut.
The king of nuts. It’s important to get it matched to the wheel, both in terms of size but also the nut’s base, which is designed to engage the wheel in a specific manner. Get that wrong, and you’ll either strip the stud that the nut mounts on, or risk a loosened nut, which could spell disaster at high speed. To properly adjust the lug nuts on your wheels, use a torque wrench. The ultimate DIY treatise written on that topic belongs to Mike Allen, an auto editor here back in the day. Sure, if you’re on the side of the road and tighten lug nuts using a cross wrench or the wrench that comes with the car, that’s fine. When you get home, double-check the lug nut tightening protocol that Mike describes in his seminal article, "Torque Wrench 101: How to get just the right amount of force." It’s a classic in DIY and industrial literature.