Justin A. Parr - Technologist

Security screws are specially-designed fasteners that can’t be removed without the corresponding, specially-designed bit.

Security screws are an excellent way to help prevent people from tampering with public facilities and resources, and to help prevent someone from creating a public safety issue — for example, security screws can and should be used in buses, trains, and airplanes.

In most applications, however, they are more of an inconvenience than a deterrent.

Meanwhile, the two most common screw fasteners, “slotted” (standard) and Phillips, are both problematic.

 

 

What Are Security Fasteners (Screws)?

Standard screws use a “slot”, and a “standard” screwdriver has a blade that fits within that slot.  Rotating the screwdriver applies torque to the outer edges of the screwdriver’s blade, which in turn, applies torque to the slot in the screw head, which turns the screw.  You use the same tool to both fasten and unfasten the screw.

Other common screw types are Phillips (“plus sign”), Allen (hex), and Torx (hex with wings).  Square drive, often considered a “security” fastener, has a square aperture, and is becoming common, as well.

On the other hand, “security” bits have an odd number of lobes (three, five, or many), posts in the center, odd-shaped tips, and / or the like.

The concept behind security screws is that everyone has these two types of screwdrivers, and they are sold in every basic home or auto repair kit in the United States:

Some people have these in their tool box, but not everyone:

Very few people have these:

 

Almost no one has these:

In other words, “Security Through Obscurity“.

The first rule of security:  “Security Through Obscurity” doesn’t work.

 

 

Appropriate Uses for Security Fasteners

There are some absolutely appropriate uses for security screws (fasteners).

In public areas, where theft could be an issue, it makes sense to use security fasteners to help prevent theft or malicious activity, as a casual deterrent — you wouldn’t want someone unbolting a public urinal, for example.

In situations where safety is a concern, for example, in public transportation applications, it absolutely makes sense to use security fasteners, to help prevent malicious tampering.

Even in consumer products, safety screws make sense to help prevent damage or injury, when placed next to a big yellow hazard label for any of the following:

• Unusually sharp objects (such as a blade or needle)
• Something spring-loaded, which when released, could cause injury.
• Unusually delicate components (maybe use Torx, no need for a security screw)
• Compartment containing poisonous substances or components
• Compartment containing reactive or explosive substances or components
• Compartment containing radioactive or radiation-emitting substances or components

To put things in perspective, I use the words “help prevent”, because you can get a security bit set just like this for about $8 at your local discount tool warehouse:

 

 

Analysis of Security Fasteners

Legal

There is no law, requiring special licensing or qualification, nor restricting access to security bits.

Therefore, anyone can obtain, manufacture, sell, transfer, own, or use them, even though few people actually have them.

Availability

As I mentioned above, security bit sets are widely available and inexpensive, thus making the lack of having one, more of an inconvenience than a preventive measure.

Knowledge / Skills

No special tools or knowledge is required to operate a security screwdriver, in order to remove a security screw.

Security screwdrivers use the same paradigm as “normal” screwdrivers, familiar to a majority of the population.

Custom-Fashioned Tools

People can visually inspect the fastener, and even develop their own tools.

I once needed an extra-long S2 (square) bit — I ground down an extra-long standard (“slotted”) bit, that I purchased for about $0.80, and made it in to an S2 bit, rather than pay $15 for an extra-long S2 screwdriver or bit.

My Physics teacher in high school took a large, slotted screwdriver, and ground a notch in to it, so that it would fit the “security” screw, holding the cover over the thermostat, so that he could adjust it whenever he wanted.

Many “security” bits are versions of “normal” bits, but have a post in the center of the fastener.  The tool for these can be constructed by starting with the “normal” tool, and using a drill press to bore a hole in the center of the tip.

Improvised Tools

Some security fasteners use odd numbers of lobes (such as 3 or 5) or many lobes (similar to a gear).  These can often be defeated using a precision-milled, slotted screwdriver, a set of which is also obtainable for about $6 at your local tool warehouse.  Although not perfect, there is usually one size of screwdriver whose blade can accurately span two or more slots on the fastener, and provide an adequate physical connection, in order to transfer enough torque, to un-screw the fastener.

Certain Allen and Torx bits are “somewhat interchangeable”, and both can usually be removed using an appropriate precision, slotted screwdriver.

Fasteners with square or hex heads can probably be removed with a socket wrench, while cylindrical-headed screws might be able to be removed with clamping pliers.

Bypass

Like all screws, security fasteners can be bypassed, either by cutting or damaging the material surrounding the fastener, or by drilling the screw head and using a screw extractor.

In some situations (especially most public bathrooms!), the security fastener is connected to a component, which is then attached using standard bolts!  The function of the security screw can be bypassed, simply by using a “standard” socket set or other tool to remove the “upstream” bolts or screws.

Many “security” screws are versions of “normal” screws, but the fastener includes a post in the center of the slot within the screw head, and the corresponding tool has an aperture that fits around the post.  Security versions of Phillips, Torx, Allen, and square drive screws can be bypassed by simply drilling the post out of the fastener itself, thus converting the screw to a standard type, that can be removed using the “standard” version of the tool.

One-Way Fasteners

There are many “one-way” fasteners that can be installed, but not easily removed.

• Rivets – Rivets are installed by drilling a hole in two objects, and the rivet is inserted through the aligned holes between the two.  A rivet tool then pulls on a pin inside the rivet, that is used to tighten, and then expand the opposite end, so that the two objects can’t be separated.  Rivets must be drilled out, to be removed.
• One-way Phillips – Like a Phillips, this fastener provides a suitable surface to apply torque, ONLY when rotating clockwise.  In the counter-clockwise direction, there is no perpendicular surface, and therefore, no torque can be applied, and the fastener can’t easily be removed.
• “Zip” Fasteners – Like a cross between a zip tie and a rivet, a plastic “nut” slips on to a ribbed post, in such a fashion that removal of the nut is prevented by blades that deform slightly against the direction of removal, effectively providing a one-way latching mechanism.
• “Shear” or “Snap” screws – Fasten using a conventional tool, such as a Phillips or Torx.  When a sufficient torque is applied, the bolt or screw head snaps off, resulting in a threaded rod that can’t easily be removed.

All of these provide better security than security screws, but can be removed using a power drill and / or screw extractor.

Security

As stated, Security Through Obscurity is not a valid security design.

This is analogous to “Hiding the door rather than locking it”, which means that anyone who knows the location of the door, without authentication, can access the door.

Anyone who buys a security bit set can remove a security fastener.

Likewise, if authentication is required, there is a valid method to ensure physical access ONLY by authenticated users:  It’s called a lock, which authenticates the user who uses the proper key to unlock it.

Unlike a security screw, which requires one of 10, or 20, or 30, or 300 different screwdriver tips, which can easily be determined by visual inspection, and subsequently obtained or manufactured (typically, inexpensively), a decent lock can’t be hacked through visual inspection, and presents one of 3,000 or more combinations (assuming 5^5 bitings vs. pin positions).  A security lock might present one of 100,000 or more combinations.

Conclusion of Analysis

The tools used to install or remove security fasteners are legal to own and manufacture, easy to obtain and use, and are inexpensive.

Either a casual attacker (opportunist) or determined attacker can obtain the tools or possibly even bypass the fastener.  A casual attacker might attempt to use standard tools to remove the fastener, and then opt for an easier target, while a determined attacker would simply be inconvenienced.  Advanced knowledge of the target via reconnaissance and observation, would allow either type of attacker to obtain the appropriate tool in advance of an attack.

Unlike a lock, neither the tool nor the fastener authenticate the user.  Further, even security fasteners and their corresponding tools must conform to some standard which limits their variability, or else they would have almost no utility.  Conversely, locks may be configured in one of thousands of possible combinations, and determining the specific configuration via visual inspection is precluded by the lock’s design.

One-way fasteners are more tamper-resistant than security screws.

Conclusion:  Security screws are more of an inconvenience than a “security” measure, and will only deter some opportunistic attackers.

 

 

Rant:  Security Screws Used in Consumer Products

<RANT>

Now that we understand the nature of, and utter uselessness of security screws, let’s take a minute to think about those times, when, while attempting to fix something, you stumble across a tri-wing screw, or one of those “Torx security” screws with the post in the center.

What problem was the manufacturer trying to solve?

Outside of a safety concern (public safety, sharp, spring-loaded, poisonous, radioactive, or reactive) accompanied by a big, yellow hazard sticker, WHY would the manufacturer use a security screw?

Here are some possible reasons, all bad:

• Prevent unqualified access.  NOPE.  I can buy any bit on the internet for a couple of dollars, whether I’m qualified or not.
• Delicate parts inside.  Yes, we know.  Using a STANDARD, but lesser used bit, such as Torx, is a great way to signal someone that “precision is involved, proceed carefully”, without pissing them off.
• Fastener is more precise.  NOPE.  Nothing is more precise than Torx.  Explain to me, how a pentalobe or tri-wing fastener is somehow more precise than Torx, which provides a positive friction lock between the tool and fastener, and delivers plenty of surface area to disperse torque evenly.

The real message to the consumer is:  “You’re good enough to buy this, but way too stupid / unqualified to fix it“.

There is NO VALID REASON TO PUT SECURITY SCREWS IN CONSUMER PRODUCTS.

</RANT>

 

 

“Standard” Screw Fasteners are Problematic

The screw thread (or worm drive) has been around since Roman times, used in presses and water pumps.

As a mechanical fastener, screws have been in use since the mid-1400’s, and came in to popular use in the late 1700’s, once mass-production techniques made them widely available.

The concept and design of a worm-drive fastener with a single slot in the top, used to provide torque between the tool (screwdriver) and fastener, remained largely unchanged for over 400 years, until Phillips introduced the Phillips fastener and corresponding Phillips screwdriver in the 1930’s.

That isn’t to say that “standard” screws were standard — other than the “screwdriver” tool itself, there were very few “standard” sizes, diameters, thread spacings, thread depths, nor taper dimensions.

The Two Most Common Screw Types Are Inferior

Although standardization in the mid-1900’s helped with fastener compatibility between multiple applications, this didn’t change some of the core flaws of the “standard” slotted screw:

• Only two possible tool alignments, oriented 180 degrees apart, makes it difficult to position the tool quickly and accurately within the slot of the screwdriver.
• The tool does not self-center within the slot, making it likely that the tool will slip off-center, or even slip out all together.
• The tool only transfers torque to the fastener along half of each face of the tool’s blade, making “cam-out” (when the tool slips out of the slot) and/or damage to the slot more likely, as torque increases.
• As with most screws, the fastener can’t be placed on the tool and subsequently set — it must be placed on the material and started from there.
• The screw absolutely requires a pilot hole.

Invented in the 1930’s, the Phillips screw and screwdriver, still in common use today, was designed to overcome many of the shortcomings of the standard, slotted screw:

• The tool can connect with the screw in one of 4 possible orientations, 90 degrees apart, making it twice as easy to align the tool and fastener.
• The tool has “blades” that taper toward  a center point, and likewise, the cross-shaped slot in the screw has sides that taper, allowing the tool to self-center and self-align to a certain extent.
• The tool has almost double the surface area, where the blades can transfer torque to the fastener.

Although a great improvement over the standard, slotted screw, the Phillips system still has quite a few disadvantages:

• Originally advertised as a “feature”, the Phillips system is designed to “cam out” (slip out of the slot), under a certain amount of torque.  This was originally designed to prevent the fastener from stripping out, and prevent damage to the material due to over-torquing.  This means that every Phillips ever made is designed to “cam out” or slip out of its slot.  This is why Phillips requires substantially more perpendicular force as the torque increases.
• Because there is a large variety of slot sizes and shapes, and because the tool is designed to “cam out”, damage to the fastener’s slot is probable, and damage to the tool itself is likely.
• The fastener can’t be pre-mounted on the tool – it must be pre-set within a pilot hole.  The shape of the tip of the screwdriver simply doesn’t support maintaining a positive physical connection between the tool and fastener.  Anyone who has tried this, and dropped a screw can attest to this fact.

What About Other Designs?

Robertson, similar to a square drive system, supports positive friction locking between the tool and fastener, and is much less likely to cam out compared to a square drive, because the Robertson bit is tapered.  Robertson is proprietary and expensive.

When dealing with worn fasteners or tools, or soft metals, square drive can be just as infuriating as Phillips.  Although somewhat compatible with Robertson, square drive is inherently inferior, due to the 90 degree angle of the tip, and lack of taper.

Allen wrenches have the advantage of having 6 possible tool alignments in 60-degree increments, where the tool can be inserted in to the screw slot.  Most Allen wrenches are “L”-shaped, and can be inserted on the short side, allowing the longer side to be used to apply more torque, or on the long side, allowing the short side to be rotated quickly for longer screw threads.  The most common problem with Allen wrenches is that there are standard (customary) and metric sizes, and using one with the other, will most likely result in a stripped screw slot or damaged tool (or both).

Torx promises greater surface area contact between the tool and fastener, can be used in 6 alignments of 60-degree increments (just like Allen), and come in standard sizes (unlike Allen) that are numbered.  The problem is that Torx is still not that common, and when engineers design something to use a Torx fastener, they often use a non-standard size.  For example, most tool sets come with about 4 Torx bits, ranging from T-8 to T-15.  Electronics often use T-6, and large, mechanical things (such as cars) use T-20 or even T-25.  So, even if you have a decent screwdriver set that ranges from T-6 to T-30, you still might not have a less common size, such as T-11 or T-13.  The biggest flaw of Torx is that the “wings” of a Torx driver can often be fragile, and wear easily, leading to stripped screws as well as cam-out.

There are many “Phillips” variants or square drive variants, that either offer interchangeability between the two, or attempt to address various limitations of either.  None of these are widely available, nor popular enough to be useful.

“Standard” screw fasteners aren’t that standard, and are actually quite problematic.

 

 

Good Design:  A Better Approach

What can we do better?

Adopt the Metric System

Two socket sets and two sets of Allen wrenches, two completely separate thread and bolt head standards…

Since the entire world uses the metric system except the United States, why do we still use the customary system?

• With global sourcing, and multi-sourcing, “Detroit” (American automotive industry) is no longer the answer.  You get a supposedly-American car with some strange mix of customary and metric bolts and other fasteners.
• “The cost to re-tool” is not a good excuse.  With new designs coming in to production every 2 to 3 years, the “next” new design could be completely metric!
• “Compatibility” is also, not a good excuse.  “Transition” bolts could be designed, that have customary thread dimensions but use metric heads.  This allows OEM and 3rd-party replacement parts to convert to metric tooling without re-engineering the part.

The only answer is: “We keep using it because we used it previously“, or more simply stated, “we have no good reason.”

Eliminating the metric system would save in so many ways:

• One set of sockets in every tool box.
• One set of Allen wrenches in every tool box.
• One set of bolts and screws in the hardware store.
• One set of machine tools.

When purchasing a set of wrenches or sockets, you invariably get half or more in “standard” (customary), and as well as a few metric.  The problem is that most tool sets provide you with the most common sizes, not all of the sizes.

So, in a 17-piece wrench set, you probably get a range of customary wrenches in sizes ranging from 1/4 up to 3/4, but you probably won’t get sizes as large as 1″, nor less common sizes, such as 5/16.

Likewise, the same set would contain some metric wrenches ranging from 8mm up to 17mm, but might not include 9mm or 11mm.

By eliminating customary wrenches, the same 17-piece wrench set could range from 6mm (about 1/4″) up to 25mm (about 1″) in 1mm increments – in other words, you purchase ONE SET of wrenches, and NEVER need a “one-off” size.

Likewise, by manufacturing ONLY metric (or metric-headed) fasteners, manufacturers only need to maintain half the machine tools, and vendors (such as your local hardware store) can stock twice as many pieces (quantity) of half the types of parts.

As many THOUSANDS of pages have been written about why the United States should abandon the customary system, I’ll stop here.

 

Use Hex Heads for Everything

How can we get around using screws, that as we know, suck?  Stop using screws that suck.

Screws should have external-facing, hex-shaped heads with no slot (like a bolt), where the corresponding tool (a socket or conventional wrench) slips completely over the bolt head, and the outer edges of the bolt head are used to transfer torque from the tool to the fastener.

Thinking of a lag bolt, which is a “big screw” with a bolt head, I’m proposing that EVERY screw should be configured this way.

Advantages:

• The “Hex head” has been fairly standard since the mid-1900’s, is widely-available, and well-vetted.
• Hex bolts have three common tool sets – the the nut or “socket” driver, the socket wrench and the conventional wrench.
• Coupled with dropping the customary system, ONE set of tools can now open 90+% of all fasteners in use.
• Using the outside edges of the fastener allows the tool to transfer the maximum amount of torque to the fastener.
• Because the tool fits around the fastener head, this allows the fastener to be set within the tool (for example, by using a magnet), securely, prior to fastening.
• Allows the tool to be positioned in one of 6 orientations, 60 degrees apart.  12-point “star” sockets are common, allowing 12 orientations in 30-degree increments.

 

Use Allen Wrenches for Surface Mount / Flush Mount

For applications requiring a recessed fastener, use Allen fasteners.

Coupled with dropping the customary system, all flush mount / surface mount and recessed fasteners can be opened with one set of Allen wrenches.

The gun industry caught on to this years ago — EVERY GUN ACCESSORY YOU CAN PURCHASE uses Allen bolts.  You bring ONE TOOL to the range, and you are good to go.

Ever wonder why everything you buy at IKEA comes with an Allen wrench?  Because it’s standard, Allen bolts can mount flush, and standard specifications are cheaper to manufacture.  I have like 10 IKEA Allen wrenches in my toolbox — all the same size, all interchangeable.

 

Use Torx In Place of Security Screws

An Allen wrench will probably strip out a Torx fastener.

Use Torx for pseudo-security / “Warning” purposes, such as applications with safety concerns.

Torx uses standard sizes, but is less common than Allen, or just regular hex bolts.

 

Use Locking Bits for True Security

Use a true lock, when security is at risk.  In public venues, and especially for transportation applications, use a true key-and-lock mechanism that authenticates the user, in favor of “hide the door” FALSE security.

Examples include:

• locking bolt “caps” (standard applications)
• locking, removable plug (surface mount / flush mount applications)
• locking panel covers critical screw heads
• locking pin that travels through exposed bolt heads, preventing tool access, and also preventing them from rotating.

 

Imagine a World

Today, you have the following tools in your toolbox:

• 5 “Standard” Screwdrivers, various sizes and lengths
• 4 “Phillips” screwdrivers, various sizes and lengths
• 4 Torx bits
• 8 “Standard” (Customary) Allen wrenches
• 8 metric Allen wrenches
• An S2 (square drive) bit (You probably DON’T have a Robertson bit — they are color-coded)
• Maybe a security bit set — 2 tri-wing, 6 “hollow” Torx, 2 “hollow” Pillips, Quad offset, pentalobe, the “hour glass” piece of crap, and a couple of others
• 1/4″ drive, “Stnadard” (Customary) socket and wrench set
• 1/4″ drive, metric socket and wrench set

If we standardize, here is your complete toolbox:

• 15 Allen wrenches, metric, in 1mm up to 15mm
• 15 sockets and 1/4″ drive socket wrench (or if you prefer, 6.35mm drive), in sizes of 6mm up to 25mm (about 1 inch)
• Torx:  T8, T10, T15, T20  (Eliminate T6 and all less common sizes)

You work for a vending company repairing vending machines.  You have a key that unlocks a panel, and exterior bolts behind the panel can then be unfastened using a hex drive.

You work for an airline.  Flush-mount screws can be removed by first removing a flush-mount cap using a special key, revealing an Allen recess, which can then be removed with an Allen wrench.  The circular lock uses 5 positions, each with 5 bittings, for a total of over 3,000 possible permutations.

 

Rant:  Shoot Anyone with a New Standard

<RANT>

Unless vetted by industry experts, adopted by standards bodies, and ratified in three countries, anyone who comes up with a new screw head fastener type should be shot on sight.

Here is how it goes:

“HEY!  I have an idea for a new type of screw fastener, that’s soooooo much better, because of ‘Q’!”

[BANG]

The next time you meet a “Phillips” or “the guy named after the hex bit with the hole in it”, SHOOT that guy in the leg.

Want to boost the economy???  

BAN ALL NON-STANDARD FASTENERS.

While you’re at it, drop the 1450’s “slotted” screw, and the 1930’s Phillips screw (designed to fail, by the way). It’s a modern world.  Adopt modern standards.

HEX, ALLEN, TORX.  DONE.

</RANT>

 

Just Kidding.  Vetting of New Standards

Fastener technology is absolutely a function of manufacturing capability.

Ever-increasing manufacturing technologies and capabilities means that new types of fasteners can be mass produced, that might have been previously expensive or too complex.

Conversely, new types of parts, materials, and manufacturing processes might necessitate a new type of fastener.

Contrary to my suggestion above, shooting the guy who solves a problem isn’t very productive.  Also, allowing 10 people to solve the same problem 10 different ways, leads to the mess that sits in my toolbox today, so that can’t happen either.

The right answer is to have a standards-based vetting process.

1. Can you use an existing fastener?  This is an ideal option, since no fastener or tool design modifications are required.
2. Can you adapt an existing fastener?  Maybe a slightly longer, stronger, lighter, or wider version of an existing fastener would fit the purpose, and maintain compatibility with existing tool sets.
3. If you must create a new fastener, can it be designed to use an existing, standard tool?  For example, new types of fasteners might work in new ways, such as a locking cam, but perhaps they can leverage hex or Allen heads, allowing compatibility with existing tool sets.  Essentially, anything that rotates could potentially leverage the same tool set.
4. Is it possible to modify and adapt an existing tool, so that it can additionally operate the new fastener?  Let’s assume you have a completely brand new fastener design, which does not use rotation to operate.  Maybe it slides, or works like a lever.  Rather than create a completely new tool set, can you cut slots in a socket end, or add a small blade to the end of a wrench, to accommodate the new fastener, and still allow the same tool to operate the older fasteners?

Anything requiring a new method of operation, a new tool set, a new manufacturing process, a modification to an existing tool set, or even a non-standard size (such as half-sizes), should be further vetted:

• Both the requirement and the design should be reviewed and approved by a standards committee.
• Thorough functional testing, to ensure that tool wear, fastener wear, or misuse doesn’t cause cam-out, or create a safety issue.
• UL-type repetitive operation testing, to observe the failure point, as well as the effect of tool and fastener wear.

Examples of poor vetting:

• Probably the most egregious example of an unnecessary fastener I’ve ever seen is the 13.5mm socket.  When the engineer sat down to design this particular fastener, he somehow decided that 13mm would not allow for enough torque, while 14mm was too large or would allow for too much torque.  This is a perfect example of something that should never make it past a standards committee — a better solution is to use the smaller bolt size, with a greater hardness rating, thus allowing the fastener to receive more torque without sheering.
• Everyone who does any type of home improvement or repair project probably has a “gnarled” Phillips screwdriver, resulting from repeated cam-out (a design feature of the Phillips system).  Repetition and failure testing would catch this type of problem – a gnarled tool is MORE likely to cam out, and destroy the fastener head in the process.
• Smaller Torx drivers are very likely to chip or wear, and can result in both cam-out and a mangled fastener slot.  This should have been caught during functional testing.

Leveraging existing standards, and proper vetting of new standards, ensures that the industry as a whole agrees with the problem, as well as the proposed solution.  Having multiple sources of input and feedback ensures that the result meets the needs of the industry as a whole, rather than just one person or company.

 

 

Tool-less Fasteners

I’m increasingly fascinated by tool-less fasteners, that can be fastened or removed by hand, without the use of any special tool.

Probably the earliest example of the tool-less fastener is the wing nut – a nut with protruding, perpendicular extensions that can be fastened or removed using the thumb and index finger.

Other common designs include:

• Lever-operated cam (compression).  The lever swings perpendicular to the axis of the fastener, and as the cam tightens, it applies tension to the central axis of the fastener.  This type of fastener is excellent for friction lock applications, such as tripods or other telescoping parts that “lock” at a specific configuration.
• Lever-operated cam (locking).  A lever operates a locking cam or “key” that rotates with the axis of the fastener.  When the cam is rotated to the correct position, it aligns with an aperture, releasing the fastener.
• Captive nut.  A standard nut is operated by, and captive within a handle or lever.  In some designs, the handle is spring-loaded, and can be “lifted” and rotated, to repeatedly reposition the fastener.
• Quick-release.  A small handle or lever operates a spring-loaded latch within the fastener.  When rotated (usually 90 degrees), the latch rotates to a position where it aligns with a key way, and can subsequently removed.
• Cotter pin.  Another simple and early design, a pin slips through a hole in a stud or metal pole, preventing a washer or other material from slipping past.  The blades of the cotter pin can be bent to prevent accidental removal as well as slippage.  When you see someone “pull the pin” on a grenade in the movies, “the pin” in question is a cotter pin with a ring on it.  Most NASCAR car hoods are held down with spring-loaded cotter pins, with a ball-bearing detente, that can be quickly removed and replaced.

 

PCs and Servers

Having built and repaired my fair share of PCs and servers over the years, I am increasingly impressed by the use of tool-less fasteners.

In the early days, your typical PC or server could be completely disassembled with a 1/4 nut driver and a Phillips screwdriver.  The case was held in place using a system of rails, and locked in place with 2, 4, or 6 sheet metal screws, which typically employed both a 1/4″ hex drive as well as a Phillips slot, and could be removed or replaced by either tool.  Once the case was removed, most internal accessory boards were held in place by a single screw, each.  Drives (hard drives, floppies, and later, optical drives) were held in place using either a system of rails, locked in place using a single screw, or perhaps up to 4 machine screws (2 on each side of the drive).

Modern PCs and Servers can be almost completely disassembled without the use of tools.  Cases are locked in place using thumb screws, spring latches, or buttons.  Once removed, snap levers hold most internal components in place, and when rotated or depressed, releases a mechanical latch or connection, allowing components to be removed or replaced.

 

Ergonomics Meets Engineering

In the 80’s, you needed  a screwdriver to replace anything except a lightbulb or a fuse.

Overall, engineers have been doing a much better job in recent years, of designing user-replaceable parts that utilize snap latches or snap levers, rather than requiring a tool.

As time progresses, increasingly “tool-less” design means a more positive consumer experience, and new types of tool-less fasteners will continue to evolve.

 

 

Summary

Security fasteners are all but worthless.

So-called “standard” slotted and Phillips fasteners, the two most common fasteners on the planet, have serious flaws.

The best solution, as an engineer designing a new component, is to use only metric hex-head fasteners, or Allen fasteners (metric only) for recessed / flush mount / surface mount applications.

Leverage existing standards wherever possible, rather than create a new solution to a problem that shouldn’t exist.