1474: Screws

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If you encounter a hex bolt, but you only brought screwdrivers, you can try sandwiching the head of the bolt between two parallel screwdriver shafts, squeezing the screwdrivers together with a hand at either end, then twisting. It doesn't work and it's a great way to hurt yourself, but you can try it!
Title text: If you encounter a hex bolt, but you only brought screwdrivers, you can try sandwiching the head of the bolt between two parallel screwdriver shafts, squeezing the screwdrivers together with a hand at either end, then twisting. It doesn't work and it's a great way to hurt yourself, but you can try it!


This comic uses a similar structure and is based off of the same idea as 1714: Volcano Types and 1874: Geologic Faults. Appliance makers sometimes use strange screw heads to hinder attempts from users to remove appliance covers. Users usually have handy screwdrivers for the first two screw types drawn, Phillips and Flat. More advanced users usually have some less standard drivers, such as Torx or Allen, however appliance makers keep designing increasingly strange screw heads and users keep acquiring increasingly strange screwdrivers.

The comic is about the frustration a user may feel when faced with a screw for which they have no screwdriver. Usually the user will try to fit one of the drivers they have handy into the strange screw, leading to damaging the screw and/or the driver and/or the person wielding the tool.

The types of screws listed are the following:

Screw type Description
Phillips head Phillips screw drive and its corresponding screw head is one of the most recognizable types of screw heads that is commonly used in construction. This type of screw head was named after its inventor, a US businessman Henry F. Phillips. Neither the inventor nor his invention have any relationship to the Dutch electronics manufacturing company with similar, but not exactly the same name Philips. Technically speaking, this is not a Phillips, as a Phillips screw head is rounded at the center; it is actually a Frearson screw drive.
Flat head Slot head screws are frequently erroneously referred to as flat heads (a flat head screw refers, in fact, to the shape of the screw head, regardless of the shape of the drive socket). The slot head is also commonly used in construction. Although the diagram shows the slot truncated, the slot almost always runs across the entire head of the screw (as in the case of the "uranium screw" below).
Uh oh. Maybe it's on Amazon? (pentagram-shaped screw) Manufacturers sometimes use screws that require special screwdrivers in order to prevent the customer from opening the product. The reference to Amazon is presumably a suggestion to search Amazon.com for the screwdriver. A number of star-shaped screw heads exist, notably the six-pointed Torx, and Apple's rounded pentalobe screw, although there is no popular design that uses the 5-pointed star shape depicted in the comic. Torx screws are common in automotive applications — Phillips heads are designed to "cam out" at high torque to protect the screw, whereas Torx do not — and on bicycles where a higher tightening torque is needed than hex screws can support. They are also commonly used on disk brake mounts and in smartphones.
Cursed −1 Phillips head The head of a screw can be stripped by overuse, tightening the screw too much, using the wrong size screwdriver, or other misuse. As the driving surfaces wear away, removing the screw becomes more difficult, and the added pressure needed to drive the screw usually damages it further.

The addition of "cursed" and "−1" in the titles is a reference to various role playing games (e.g. Dungeons and Dragons), where magical "cursed" items appear frequently. This often makes the cursed equipment (in the case of armor or weapons) incredibly difficult to remove, as it will cling to the wielder. Similarly, the cursed Phillips Head screw becomes difficult to remove due to the stripped head. Alternatively, this may imply that the damage to the screw head was caused because the screw is "cursed" and therefore difficult to remove.

The "−1" refers to the damage of the screw head. In role playing games, items such as weapons and armor may have an "enchantment", with a positive enchantment making the item more effective, and a negative enchantment making the item less effective. Negatively enchanted items are often also cursed, as is the case with this screw head. The "−1" does not appear to be a reference to a Phillips bit-size number, as those are always positive.

Crap, it's a rivet. A rivet is not a screw — it is a permanent fastener which is secured by deforming the body of the fastener. Rivets cannot be removed with a screwdriver, they must be drilled out. Some bolts also have rounded rivet-style heads, though, which need a collet-style tool to grip and remove.
Phillips head ruiner (actually a hex screw) A reference to the fact that hex socket screws can, in a pinch, be removed with a Phillips screwdriver (rather than the intended Allen wrench) but this will likely ruin the screwdriver (and damage the screw) in the process.
Uranium screw Uranium screws were used in the construction of nuclear weapons during the twentieth century. Multiple radially extending short wave-like lines around the screw head symbolize radiant energy output, although real uranium screws were most likely made of unenriched Natural uranium.
Phillip's head This is a morbidly literal interpretation of the misuse of an apostrophe in "Phillip's head". This "screw" is actually a bloody bag containing the severed head of someone named "Phillip" (an all too common modern respelling of the more classic "Philip", perhaps in part influenced by the more typical "Phillips" surname). Intentionally or otherwise, this last punchline could be described as a "mind screw".
Hex bolt (title text) A hex bolt has six external sides, so it could in theory be held by squeezing two screwdriver shafts together with the bolt in-between, as an ersatz pair of pliers. The amount of force on the two screwdriver shafts needed to turn the hex bolt and maintain the 'grip' will probably exceed the strength of human hands — the attempt would most likely only result in causing your hands to cramp or causing the screwdrivers to slip and cause further injury. The title text is making a play on the phrase "you can try", which normally implies something with a reasonable chance of success, but here is only pointing out "just because you can doesn't mean you should".

It marks a variation on the idea that "when all you have is a hammer, everything looks like a nail", as also exemplified by the common tendency for cutting-pliers to be used to grip things or gripping pliers to be used to try to flex-shear objects, just because one tool is more immediately at hand than a more correct one. But, in this case, it seems that multiple screwdrivers are available. Whether or not any of these are strictly suitable for all actually encountered screw-heads (as above), here something that is definitely not actually a screw-head still "looks like one" and forces a gross improvisation in leiu of any of the more suitable tools that should really be used — including an external hex socket of a suitable size.


[Eight drawings of different types of heads each with a caption:]
[Plus sign-shaped screw.]
Phillips head
[Minus sign-shaped screw.]
Flat head
[Star-shaped screw.]
Uh oh. Maybe it's on Amazon?
[Plus sign-shaped screw with worn edges.]
Cursed -1 Phillips head
[No screw, just a circle.]
Crap, it's a rivet.
[Hexagon-shaped screw.]
Phillips-head ruiner
[Minus sign-shaped screw going through the whole circle. Also giving off radiation.]
Uranium screw (a real thing)
[A sack with blood oozing out of it.]
Phillip's head

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This page is now on the first page of google for "uranium screw". Mrmakeit (talk) 05:31, 16 January 2015 (UTC)

And as of now, this page is the #1 result for "uranium screw". The second is the xkcd fora thread on this comic, and the third is our home page. NealCruco (talk) 16:47, 16 January 2015 (UTC)

I don't think that patent is the right one, it seems to describe a uranium decontamination procedure, not a screw made of uranium like in the comic. LeoDeQuirm (talk) 05:46, 16 January 2015 (UTC)

I'm pretty sure the "uranium screw" is just a reference to the fact that the head of the screw appears to have split in two ("fissioned"), as opposed to a normal flat head screw that still has the edges connected. Sam887 (talk) 05:50, 16 January 2015 (UTC)

Just a shot in the dark here, but a company that sells uranium ore and radiological equipment happens to also sell screws for one of its Geigers that look just like the screw cross-section in the comic. [1] Conqu2 (talk) 06:01, 16 January 2015 (UTC)

I was wondering if the "uranium screw" was referring to the Demon Core -- two hemispherical domes that Louis Slotin was holding apart with a screwdriver. Then I remembered the Demon Core was plutonium, not uranium. 06:49, 16 January 2015 (UTC)

There are ferrous alloys containing (depleted, of course ;-) uranium for "increase[d] toughness and strength". [2] Knob creek (talk) 09:21, 16 January 2015 (UTC)

I think the be was going for apple's pentalobe screw with the 5 pointed star (talk) (please sign your comments with ~~~~)

I don't think the uranium screws are named for their use in stuff to do with uranium, as I have both seen and used screws that look like that before. It's basically a flat head screw whose divot extends all the way across the face of the screw. I agree more with the previous commentor who notes that the screw looks like it has fissioned. 06:34, 16 January 2015 (UTC)

An actual rivet is neither a screw nor a bolt; it's a fastener that is placed and then has one end plastically deformed -- traditionally by a rivet gun, but more often in smaller sizes by some sort of press or clamp. (Pop rivets are hollow, and are deformed by pulling a cone-sheaped wedge into the open end of the hollow core.) There's no way to remove one except to destroy it (drill it out or cut one end off). The item pictured could also be the head of a carriage bolt, but that's no help if you can't get at the other end of the bolt. Randall is slightly pessemistic, though: there *are* some "security" screws and bolts that use a slightly-elliptical domed head that's hard to tell from a rivet; they can be unscrewed, but only with a matching slightly-elliptical socket. 06:35, 16 January 2015 (UTC)

All of which can be removed by a sonic screwdriver. Totally a real thing. (talk) (please sign your comments with ~~~~)

Could the "cursed -1" be a Nethack reference? I don't know if Dungeons and Dragons has the "blessed/uncursed/cursed" status, but in Nethack cursed items with negative enchantments (denoted "cursed -whatever") are a pretty common occurrence. 07:31, 16 January 2015 (UTC)

In Nethack, Cursed objects cannot be removed. Seems appropriate. At first I thought it was a pozidrive screw head. Posts on the fission screw head: where have you seen screws whose divot does *not* extend across the head? (talk) (please sign your comments with ~~~~)

Kreuiter (talk) 08:03, 16 January 2015 (UTC)from wikipedia: Louis Philippe Joseph d'Orléans (13 April 1747 – 6 November 1793) commonly known as Philippe, was a member of a cadet branch of the House of Bourbon, the ruling dynasty of France. He actively supported the French Revolution and adopted the name Philippe Égalité, but was nonetheless guillotined during the Reign of Terror

I don't think it is specifically a reference to Nethack as a lot of ol games (both video and tabletop) use the mechanic of non removable cursed objects. It is common enough in my opinion that we could argue about until we are blue in the face and get nowhere. (talk) (please sign your comments with ~~~~)

uranium screw may be a reference to Louis Slotin, who died when he was using a screw driver to seperate two halves of a plutonium sphere as part of a science demonstration, and triggered a large burst of radiation when his hand slipped. -- 08:28, 16 January 2015 (UTC)

I'm thinking it might benefit the article to include a place in the wikitable for the correct term for each drive socket. Of course their are not correct terms for each of them. Not to mention rivets and Phillip's heads don't even have drive sockets. 09:04, 16 January 2015 (UTC)BLuDgeons

If you suggest cursed-1 is because if misuse - I in first place thought of [3] as the cursed one - because Philipps and Pozidriv are slightly incompatible and causes damage. 09:09, 16 January 2015 (UTC)

+1, the cursed one looked to me like pozidriv at the first glance, and it's really cursed as interchanging them leads to damage ... And the most fun is when you get some Chinese crap that looks like pozidriv but it doesn't fit so you use philips which doesn't quite fit too but at least it can be inserted and you end up damaging both the driver and the screw :-/ --kavol, 10:02, 16 January 2015 (UTC)

Is it really true that Phillips head are 'commonly used in construction'? At least in Europe they were replaced by Pozidriv in the 1990's and these days by Torx. -- Popup (talk) (please sign your comments with ~~~~)

As a former (late 2000s to 2012, pre-college) construction worker in California, Texas, and Oklahoma, yes. Philips are very common in construction here. 06:08, 17 January 2015 (UTC)

Maybe this depends on the quality of the product? If i look around, i find lots of products held together by phillips screws and only a few (usually more hi-tech and expensive) one with torx screws. Knob creek (talk) 09:28, 16 January 2015 (UTC)

er, what do you call "a product"? - If "construction" is mentioned, I imagine things like wooden skeleton of a roof, fastening of windows/doors, self-tapping screws, wallplug screws ... and it's almost 100% pozidriv and torx here in central Europe. ("Almost" accounts for imports by non-european companies.) If I imagine metal constructions, from racks to bridges, hex and inbus (= hex slot) prevail. --kavol, 10:02, 16 January 2015 (UTC)
Granted I'm not in the construction trade, and I'm in UK rather than continental Europe, but I have never seen Torx used in construction. In my experience, the majority is Pozi, and the rest is Phillips. --Pudder (talk) 13:06, 16 January 2015 (UTC)

Perhaps a reference to http://xkcd.com/927/ - Standards?

Phillips screws have a larger number for larger size, not smaller. (talk) (please sign your comments with ~~~~)

I'm surprised Randall didn't include square/Robertson screws/drivers. Just as bad as hex-recess, but when you actually USE them they are great! Combination Robertson-Phillips are good too but rarer. And do NOT get me started about the untold types of tamper-proof designs... --BigMal // 13:06, 16 January 2015 (UTC)

The most awkward, I find, are star-shaped (5/6-pointer) screws with a central 'post' that requires a hole-ended screwdriver-bit of the appropriate shape to be used (may also aid in positive positioning of the tool, but not much more than normally so SFAICT it's just there to be awkward without the right tools by manufacturer-mandated professionals). Luckily, I've got screwdriver-heads for just about every conceivable 'uncursed' screwhead (48 different types and sizes in one handy kit alone, not even counting socket-heads and 'cursed' screw drilling-outers). Especially good for laptop repair, to get around deliberately proprietry systems with small and (deliberately) akward screws; as opposed to bicycle repair, which I'm sure is usually for the stated practical torque reasons. 13:59, 16 January 2015 (UTC)

"cursed -1 <something>" is definitely a standard NetHack item description format, but it applies to D&D too. In general, "cursed" means you cannot remove the item, and the number is describing the item's effectiveness compared to a standard (+0) version of the item. In this case, both can be appropriate: "cursed" because -as noted- you cannot remove it in the normal way. "-1" probably comes from being unable to tighten the screw far enough to fully satisfy its purpose: maybe the joint is slightly loose, or the head of the screw is left slightly protruding, so that it easily catches on other things. 13:28, 16 January 2015 (UTC)

Rather than two (still) separate fissile hemispheres, that 'gap' is obviously a continuation of material around the back of a schematic cross-section of a whole sphere with a core currently missing. I think the fissile plug will be inserted/fired at the required juncture to fill this, from the side. Very like the device in the film The Fifth Protocol, for easy cinematic reference of the concept. (Noting that 'gun-type' nuclear devices tend to fire the 'enclosing' larger subcritical mass, spheroidal or cylindrical onto the smaller and fixed 'plug' to fill the gap between it and the surrounding neutron reflector jacket. For several very good reasons. Thus that sphere would be shoved onto the currently missing 'core', although it makes the reflector assembly and positioning a bit more complex as well, compared with a cylindrical sleeve.) 13:49, 16 January 2015 (UTC)

The Cursed -1 Phillips Head is much more likely to be a Pozidriv head than a worn Philips head. The cursed -1 implication if used with a Philips driver is certainly deserved. 14:59, 16 January 2015 (UTC)

Re: Uranium Screw... see http://www.google.com/patents/US20060088457 (talk) (please sign your comments with ~~~~)

Uranium screws were used in the assembly of the Fat Man nuclear bomb. All parts of the tamper were made with natural uranium, including the screws and hinges: http://blog.nuclearsecrecy.com/2014/11/10/fat-mans-uranium/ Rocbolt (talk) 15:34, 16 January 2015 (UTC)rocbolt

User:Rocbolt has it right. It's not a metaphor or a joke. https://www.google.com/search?q=%22uranium%20screws%22%20%2dxkcd Pesthouse (talk) 15:41, 16 January 2015 (UTC)

Did anyone notice that the "shortcut icon" of the page was changed together with this comic? Its sort of blurred: http://i.imgur.com/ArEbL5r.jpg?1 compared to the original image http://xkcd.com/s/919f27.ico (talk) (please sign your comments with ~~~~)

Possibly a reference to Apple's iPhone "tamper-resistant" screws http://en.wikipedia.org/wiki/Pentalobe_screw 17:38, 16 January 2015 (UTC)

Screws made of uranium were used to hold the tamper plug of the fissile core of the Trinity nuclear device together. I think that's what "Uranium Screw" refers to, and why the screw is radiating: it is radioactive. Arnold Chiari II (talk) 15:35, 16 January 2015 (UTC)

Not sure why the page says depleted Uranium. I think they were natural uranium, which is radioactive. Rocbolt's reference supports this Arnold Chiari II (talk) 21:26, 16 January 2015 (UTC)

Depleted uranium is nearly pure U-238, which is radioactive, but has a half-life 6X longer than U-235.

Technically, a rivet is a bolt, but the usage of bolt to refer to a non-threaded object with a head is archaic.

I have seen a few objects that look like "flat head", where the slot doesn't extend all the way out to the edge, but precious few, compared to the fairly common "standard" woodscrew, where the slot goes all the way to the edge, as shown at "uranium screw".

I thought "Cursed -1" was a clever double reference to the common RPG meme and to what happens after someone has confounded Philips, Pozidriv, or Reed and Prince with one of the others and the fireworks from using a tool designed for one on a screw of another type.-- 00:32, 17 January 2015 (UTC)

Could the Amazon one be a reference to star ratings? -- 01:58, 17 January 2015 (UTC)

My thoughts exactly. And another thing: the slot of the flathead doesn't go "through" because this makes for a visual +/- gag. 20:22, 17 January 2015 (UTC)

The rivet could also be a nail. While a nail isn't a screw, neither is a rivet. Glen442 (talk) 03:20, 17 January 2015 (UTC)

I think the bit about "Phillip's Head" is an obvious note about the frustration of dealing with different screw types -- as in "I'm so frustrated dealing with all these screw types I'm going to find the inventor of the Phillips head screw and chop his head off!" (talk) (please sign your comments with ~~~~)

CHOP? I think that you are missing the point of the comic... I wonder how many screws you would need to put into someone's neck for the head to fall off... RedHatGuy68 (talk) 04:35, 10 May 2016 (UTC)

Shouldn't that be 'an allen key' and not a wrench? I'm willing to acknowledge the inventor (Allen) but it's a key, not a wrench, by any definition. 23:34, 17 January 2015 (UTC)

Isn't Philip's head a joke about his frustration with types of screws? Halfhat (talk) 17:34, 18 January 2015 (UTC)

It is my opinion that "Phillip's Head" (the bloody sack) is actually a reference to "King Philip" (note the spelling with only one 'L'), an American Indian of the Wompanoag tribe in the latter 1600s who was the leader of an uprising against the settlers of Plymouth Colony. He was killed in 1676 and his corpse mutilated, with the head separated from the body and the body itself dismembered. The head was spiked and carried to Plymouth Settlement, eventually being placed on the Plymouth Colony Fort where it was left to languish for some 25 years. The head (by now merely a jawless skull) was eventually secreted away by a colonial family that was friendly to him; they kept King Philip’s head for many generations before giving it to his descendants. 09:58, 18 January 2015 (UTC)

Perhaps the five-pointed star screw and its Amazon reference refer to the fact that it looks like a review star on Amazon? (talk) (please sign your comments with ~~~~)

I feel I have to question the phrase "Imperial-sized hex screws do sometimes surface, to the dissatisfaction of anyone who owns a hex driver set." As a mentor for a FIRST Robotics Team (Go 811!), we use Imperial-sized hex screws all the time. And here in the US, Imperial hex/Allen wrenches/keys are more common than their Metric counterparts. (sigh ... maybe SOMEday we'll wise up and go metric ...) --Mr. I (talk) 18:58, 19 January 2015 (UTC)

I've just removed what I consider to be excess bloat from the explanation. I'm sure some people will disagree, but to me the descriptions of the screws were getting bogged down in excessive an unecessary details. As an example, the fact that torx screws are able to be used for higher torques really doesn't have anything to do with the comic. The long rambling sentence about french royalty being guillotined was interesting (to me at least), but didn't really come to a conclusion. --Pudder (talk) 17:23, 21 January 2015 (UTC)

I believe 'Uranium Screw' is referring to a screw with a "half life" of sorts - these types of flathead screws (which obviously exist, just are not as common) tend to "split in half" when they fail as opposed to just stripping. Half of the head splits off, similar to uranium decaying halfway. 16:58, 21 February 2015 (UTC)

The Torx standard is primarily a 6-pointed star, but a 5-pointed star is used for smaller wire types, as noted on http://en.wikipedia.org/wiki/Torx. 16:49, 15 May 2015 (UTC)

Just my 2 cents, since a lot of commentators were writing about the types of screws they're most familiar with. Here in Brazil, at least where I live, the standard is slot and Phillips, with the latter becoming more prominent. Allen and Torx are used in more expensive products, like HDDs and cars. I've only known about Pozidrivs from Wikipedia. I can't speak for the construction area, but I suppose it doesn't change much. 18:45, 7 December 2015 (UTC)

I wrote too soon. I just found Pozidriv screws in a sofa's feet. 19:23, 10 December 2015 (UTC)

Uh oh. Maybe it's on Amazon? (star-shaped screw) - 5 point 'torx' is somewhat common in automotive industry as a temper proof alternative to regular 6 point torx. Some examples would be MAF sensors and old Mercedes Benz rearview mirrors -- C0llidee (talk) 01:40, 29 December 2019 (please sign your comments with ~~~~)