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Comment by imgabe | Hacker News Reader

My first thought was "Are customs officers so stupid that they need to be told this?". But then my second, more cynical though was "Someone, somewhere, will question their methodology in distinguishing a bolt from a screw for some obscure legal purpose (maybe to avoid a tariff on screws that doesn't apply to bolts?) and they need this document to point to in order to explain in a defensible way why they made that distinction".

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Evidently at least one lawsuit prompted the drafting of this semi-august publication. Good government means, in part, consistent and reliable application of rules -- even if it's as minute as the distinction between bolts and screws!

This, in my mind, is a very particular example of the general case of good government often being inefficient governance. We are protected against tyranny, in an infinitesimal and indeed ridiculous way, by colorless bureaucrats dedicated to the proposition that every bolt shall be labeled a bolt, and each screw a screw, regardless of the power and wealth of those who might carry them through customs and seek to see them mislabeled. Godspeed, writers of CBP Informed Compliance Publication minutiae, godspeed.

Consistent and reliable application of rules would preclude creating needlessly complex differentiations between two terms that basically refer to the same thing.

The modern inability of an individual to independently and easily interpret the law is violation of equal protection.

(IMHO the items described downthread by DannyBee sound like the canonical thing most people picture when they hear "bolt")

They don't "basically refer to the same thing". They are different items that serve different purposes. They may appear similar from a distance, but go try to hang drywall with some machine bolts, then come back and tell me that they're "basically the same thing".

Your reasoning implies that one can hang drywall with sheet metal screws, simply by virtue of them being called screws.

No, it doesn't imply that at all. How do you draw that inference?

You implied that the reason one cannot hang drywall with machine bolts is specifically because they're bolts. If being called bolts vs screws were such a reliable indicator of functionality, then one would expect sheet metal screws to be much better at hanging drywall than say flat head machine bolts.

BTW I personally call them machine screws. To me, the difference has more to do with what kind of drive they take, whether they're self-tapping, how big they are, or really just what kind of mood one is in.

I'm well aware of many types of threaded fasteners, which is what makes trying for a general formal distinction between bolts and screws seem ridiculous. To me, it seems like more a matter of personal taste and dialect, bureaucrats attempting to force their prescriptions onto the world notwithstanding.

Any one definition can capture most of the distinction, but leaves a remainder that's outright wrong. The CBP definition seems intuitively decent until you realize that the same item will be a screw or a bolt depending on the intent of the user. That's exactly the kind of ambiguity that keeps lawyers entrenched and erodes the rule of law.

If a welded nut breaks free, does its screw become a bolt? When a nut gets tight enough to not spin on its own, does a bolt change into a screw?

Sheet metal screws would be better than bolts at hanging drywall. They still wouldn't be good at it because that's not what they're for, but they at least have a pointed tip that can dig into the drywall and penetrate it compared to a bolt with a flat tip that is going nowhere without a pre-drilled hole.

Personal taste and dialect are all well and good, but when Screwco sues the US government to say they shouldn't have to pay the screw tariff, because they're actually importing bolts not screws, the government lawyer can't stand in court and say "Well, your honor, we think it's our personal taste to call these things screws and those things bolts because that's just what we think and it's common sense, everyone knows it."

The government has a much stronger argument if they can say "See we published this document which specifically defines what we consider a screw and what we consider a bolt and as you can see this object has the physical characteristics of what we call a screw, so Mr. Screwco does in fact have to pay the screw tariff."

Personal taste is not generally a legally defensible position, which is what I'm assuming the purpose of this document is, not a philosophical treatise on the existential nature of screws vs. bolts.

Actually I just walked over to my drawers and the first sheet metal screws I found would be decent drywall screws (flat heads and everything), except for the presumed increased cost. For machine bolts, I was picturing long 4-40 ones, hammered into the stud to get started. This seems like it would work as well, just even less efficient cost wise for a longer body to compensate for the shallower thread. But anyway back to the argument

There apparently was this case: https://news.ycombinator.com/item?id=12341278 . But the items described sound like canonical bolts! Apparently the company turning their head when installing them legally changes that. So now we've got a legal definition that is abruptly different from how most anybody actually skilled in the art would classify them if actually forced to choose exclusively between the terms "screw" and "bolt".

My point is that perhaps if terms are so close to be generally interchangeable in common usage, then perhaps the legal system shouldn't be trying to differentiate between them at all! It's a code smell of being at the limit of understanding. The government should only be creating general rules that are straightforwardly interpretable by the average person, not attempting to catalog and dictate every minute domain aspect top-down.

Perhaps there wasn't a lawsuit, but rather this is an artefact of the organization the created it, in Northcote Parkinson style. That is to say, perhaps Sally, a middle manager in the NAFTA Bureau, Cyclicals Division, Building Materials Department, Fasteners Group, has five reports and each of them plays a vital role.

Godspeed, Sally.

There was a lawsuit:

"U.S. Customs and Border Protection (CBP) uses the “Specification for Identification of Bolts and Screws,” ANSI - ASME B18.2.1 1981 (the “Specification”) to distinguish bolts from screws.1 In Rocknel Fastener, Inc. v. United States, 24 C.I.T. 900, 118 F.Supp. 2d 1238 (Ct. Int’l. Trade 2000), the Court of International Trade (CIT) sanctioned the use of the Specification for this purpose, stating that it provides a well-recognized, comprehensive basis for the common and commercial meaning of bolt and screw as understood by the fastener industry in the United States. See Id., at 906 and 913, 118 F.Supp. 2d at 1243 and 1249. The standard is full of industry jargon, so to make it easier to use, we have combined it here with illustrations and glossary terms from Fastener Standards 6th Edition, Industrial Fasteners Institute, Cleveland, Ohio 44114, 1988."

Yes, and in case anyone wanted to question whether this really came up there, i'll give the relevant paragraphs:

"The products at issue in this case consist of a variety of metal fasteners that Rocknel imported from Japan in 1997. The fasteners, which are fabricated from metal alloys, have rod-shaped bodies and hexagonally shaped heads. Their bodies are fully or partially threaded. Rocknel has admitted that the fasteners were designed to be installed in holes of assembled parts and that the fasteners were designed to be tightened or released by turning their heads.

...

The Customs Service liquidated the fasteners under subheading 7318.15.80 of the Harmonized Tariff Schedule of the United States (“HTSUS”). Subsequently, Rocknel filed a protest, claiming that the fasteners should have been classified under HTSUS subheading 7318.15.20."

(15.80 is screws, 15.20 is bolts)

...

"The court concluded that the tariff schedule required that the terms “bolt” and “screw” be given mutually exclusive definitions.

...

Because Customs had looked to the ANSI Specification as the source of the definitions of “bolt” and “screw” for tariff classification purposes, and because Rocknel had admitted that under the ANSI Specification the fasteners at issue in this case would be classified as screws and not bolts, the court granted summary judgment to Customs upholding the agency's classification of the fasteners."

I secretly thought the diagrams were kind of cool. I'm saddened to learn they were taken from elsewhere.

Even with your first point, is the distinction really so obvious? Of course I can think of items which are obviously bolts and not screws, and vice versa, but I can also think of items where I have no idea which way they would be categorized.

The document reveals some pretty subtle distinctions. For example, "An externally threaded fastener, which must be assembled with a nut to perform its intended service, is a bolt." But, "An externally threaded fastener, which must be torqued by its head into a tapped or other preformed hole to perform its intended service is a screw." Couldn't the exact same fastener fit either definition depending on the context in which it's intended to be used?

And yes, it seems your tariff theory is on point. "STEEL SCREWS AND BOLTS are classified in Chapter 73, Harmonized Tariff Schedule of the United States (HTSUS) under heading 7318. The tariff has separate provisions for the different types of screws and bolts, and separate provisions for threaded and non-threaded fasteners."

> Couldn't the exact same fastener fit either definition depending on the context in which it's intended to be used?

Nope. The two definitions are mutually exclusive, that's the point!

Give me an example when a screw uses a nut. There isn't one, because when a fastener uses a nut, its a bolt!

Give me an example when a bolt has a thread that produces from the shaft body. Again, there isnt one, as this would make it a screw.

From section 3 of the PDF: "Because of basic design, it is possible to use certain types of screws in combination with a nut"

Also take a look at the "Square Head Set Screw" in section 5.4 and https://en.wikipedia.org/wiki/Screw#Differentiation_between_....

[also: https://en.m.wikipedia.org/wiki/Screw#United_States_governme... explains why the government needs to define this: different tariffs. That page also mentions "In 1991 responding to an influx of counterfeit fasteners Congress passed PL 101-592[12] "Fastener Quality Act"". Apparently, screws/bolts got imported as bolts/screws]

When you put a nut on a machine screw it doesn't cease to be a machine screw, but it works and I do it frequently. However, the document accounts for this in section 3: "Because of basic design, it is possible to use certain types of screws in combination with a nut. Any externally threaded fastener which has a majority of the design characteristics which assist its proper use in a tapped or other preformed hole is a screw, regardless of how it is used in its service application."

Take a threaded fastener and insert it into a threaded hole. By the definition given here, it's a screw. Now remove it and put a nut on the end instead. By the definition given here, it's been transmuted into a bolt despite no physical changes to the item itself.

Can you clarify what you mean when you say, " thread that produces from the shaft body. " - I read that phrase over a few times, still not clear what you are saying.

Get a pencil, now wrap a piece of string around it. The string protrudes from the pencil "shaft body" as per a screw.

Conversely in a bolt, the thread is machined into the shaft; imagine carving the line that the string made into the pencil (so that you are removing rather than adding material) to produce the thread.

So you are saying that if the threads are sunken below the shaft, then that suggests you have a bolt, but if the threads are above the surface of the shaft - that suggests screw?

Now on a quest to find a screw with threads sunken into the shaft, defining said screw as something that is only tightened by applying pressure to the head.

https://www.boltdepot.com/Product-Details.aspx?product=1884 almost is fully sunken into the shaft ("no, the shaft gets thinner" IMO is not a valid argument)

But that's a case where the threads are definitely external, not internal to the shaft. The threads are the skinny part, and they are raised above the shaft in the version you just sent.

How do you know whether the whole shaft was equal in width to what's now closest to the head and something was cut away or whether it was smaller to start with, and something was added?

Or,is your argument that this could be a screw:

    /\_/\_/\_/\_
                \
    _  _  _  _  /
     \/ \/ \/ \/

but this

      _  _  _  _
    _/ \/ \/ \/ \
                 \
                _/
    \_/\_/\_/\_/

cannot be because the outside isn't sharp enough to 'bite' into the material it is screwed into?

I can see the latter holding in rubbery material that tears easily.

First, hero points for doing a text based screw description.

Second, I assume that 100% of screws and bolts are created by cutting away - hard to imagine adding something to the outside of a shaft. The only question is whether the resulting threads are raised above the shaft (screw)- by cutting away the shaft, or sunken below (bolt), by leaving the shaft in place and cutting in the threads.

I realize there is nuance here - which is why I"m interested in seeing if I can find a screw (or bolt) that seems to break this pattern.

You're right, I always though my desk was held together with bolts but today I learned it uses screws!

I suspect there's probably high stakes involved for somebody, at some point in the fastener supply chain, based on whether their product is classified as a "screw" or a "bolt". E.g. there could be different import duties on screws vs. bolts based on the location of manufacture. (I'd hazard a guess that duties on screws are lower, while bolts are higher, because protecting the domestic structural bolt industry was probably viewed as more of a national interest at some point.)

There's also some grey area between "screw" and "bolt" particularly when you get into what are conventionally called 'machine screws'. For instance, you can get very large socket cap 'machine screws' that are the size, and could easily serve the purpose of, large hex bolts. The only difference is the use of an internal hex head vs. an external hex, which doesn't matter all that much given modern drivers. It would seem, based on the CBP's definition, that a socket head "screw" of any size would be a screw as long as it's continually threaded, but the moment it has any amount of unthreaded shank, it might be classed as a bolt.

So it's not surprising to me that the document exists, although the fact that it does exist hints at the byzantine nature of the Customs system.

Not so much a CBP problem as FAA and civilian lawsuit, but aerospace rated fasteners for large airplanes and space applications are serious business. To the extent that a few bolts for a beechcraft can cost $300 in a little plastic baggie.

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