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Screw, Bolt… Nuts!

The folks at Highland are real "sticklers" for accuracy, and if I make a mistake, boy do I hear about it. Like in the video about the new Rikon Tool-Less Blade Guard Upgrade Kit when I called a screw a bolt… or a bolt a screw… or a bolt a nut… nuts! I don't even remember!

Have you ever done that? Imagine describing something to someone and you get wound up and excited and accidently call a screw a bolt or a bolt a screw or worse. You've never done that? Hmmm, you wouldn't be pulling this old woodworker's leg, would you?

Well, anyway, it got me to thinking, what exactly is the difference between a screw and a bolt? I just finished assembling my new Supermax Drum Sander , and in the instructions I distinctly remember something called a screw, that for all intents, looked very much like a bolt to me!

Figure 5 - Everybody knows a screw has a sharp point... or does it?

So, like everyone does these days, I got a cup of coffee, plopped myself in front of the computer and "Googled" it. And guess what? There is actually no set-down-in-stone, agreed-upon definition that precisely describes when a screw should be called a screw, and when a threaded thingamajig should be called a bolt. So I started asking experts.

Figure 6 - Drill a hole in metal and "tap" it with a thread size to match, screw this in, and it is a screw. Drill an oversize hole, slip this in and put a nut on the end of it and it is a bolt

All kinds of answers ensued. "A screw has a point on the tip." True, but there are screws that don't have pointed tips. "A screw is what you use a screwdriver on, on a bolt you use a wrench." Well, then, what about lag screws? "A bolt isn't threaded all the way to the top." Oh, but some are. And what about screws that aren't threaded all the way to the top… think pocket hole screws. I really wasn't trying to be argumentative, but it seems like every answer I got was easily disproved or led to yet another question. One guy said, "If it has a head on one end it is a screw." Huh? Bolts have heads, too! One person simply explained that "A bolt is bigger than a screw." Really? Go to the big box store and compare an 8-32 bolt and a #14 screw. One person told me that "with a screw you turn the screw to tighten it, with a bolt you turn the nut." Gee, I think I've been doing it all wrong about half the time all these years.

Machinery's Handbook states, "A bolt is an externally threaded fastener designed for insertion through holes in assembled parts, and is normally intended to be tightened or released by torquing a nut. A screw is an externally threaded fastener capable of being inserted into holes in assembled parts, of mating with a preformed internal thread or forming its own thread, and of being tightened or released by torquing the head.

Figure 7 - The manufacturer calls this a screw... it sure looks like a screw except there is no sharp point on the end

Okay, I get that. But if you are a frugal saver of fasteners, consider this… you remove a screw, which definitely was a screw by that definition because it was inserted into a pre-threaded hole. You save that non-pointy threaded screw. Later, you find a nut that fits it perfectly. What was once a screw now becomes a bolt because you have attached a nut. Transmogrification!

It appears from all my research and all my conversations, there really is no clear consensus. But here are a couple of things that might help identify some types of fasteners:

1. If the "fastener" is inserted into the material and forms its own threads, or matches threads already formed in the piece, it is a screw. I don't know where a bolt that goes through a couple of work pieces or parts and then threads into a weld-nut would fall in this, but hey…
2. If it takes two tools to tighten, it is probably a bolt and a nut… just one tool to tighten, you are safe to call it a screw.
3. Anything with a sharp point on it can reasonably be considered a screw, but there are a lot of screws that don't have pointy tips… so this is just a partial "process of elimination" answer.

Figure 8 - Everybody, including the manufacturer, calls this an eyebolt... but it is sharp and pointy on the end and makes its own threads as you "screw" it in. Confused yet? Maybe that is why my Dad called it a "screw-eye"

If you call a screw a bolt, or a bolt a screw, don't worry, you are among friends here… and we are smart enough to figure out what you meant. But if you call either a bolt or a screw a nut, look out! That is an egregious mistake. Uh, except we have these cool sets of nut drivers that we actually use on the head of a bolt but we turn them just like a screwdriver. Nuts! I give up!!!

Be sure to tune in and watch the next installment of the Sliding Bypass Door project video series . The doors are almost finished, but it's time to mount the tricky roller hardware, and it gets a little weird.

My next project is going to be real humdinger, and you are absolutely going to want to build one for your shop… no, I'm not giving any hints what it is, you will just have to stay tuned!

By the time you read this, summer is likely (finally) in full swing wherever you are and I hope that you are enjoying wonderful weather and putting all your woodworking skills to use on something nice in the great outdoors.

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Steven Johnson is retired from an almost 30-year career selling medical equipment and supplies, and now enjoys improving his shop, his skills, and his designs on a full time basis (although he says home improvement projects and furniture building have been hobbies for most of his adult life). Steven can be reached directly via email at sjohnson@downtoearthwoodworking.com

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