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What Are Spanner (Snake-Eye) Security Bits

The spanner security drive style is a security drive style. It is called a security drive style because it has an unconventional driving method. The spanner security style uses two points on the bit that sit into the recess of the fastener head. This makes if very difficult to remove or tamper with without using the proper bit.

Spanner Security Drive Style

What Are Spanner Security Bits Used For?

Spanner (Snake-Eye) security bits are used for making installations more secure. By adding an unconventional drive stile in public areas, they are much less likely to be vandalized or tampered with on a whim. Spanner screws can be seen commonly on public applications such as: Bathroom dividers and Public Art Displays.

Why are Spanner Security Bits More Likely To Break?

While spanner security bits are one of the best security drive styles around for adding extra security to applications, they do have a big downside. A Spanner bit has two teeth that are inserted into the drive recess for fastening. Due to this style, all of the torque is generated by the force on those two points. This puts them under a great deal of stress when installing. This extreme stress on two points makes them much more susceptible to snapping than other types of bits.

Situations That Cause Spanner Bits To Break and How to Prevent Them

There are several reasons that spanner bits commonly break. Luckily, most of them can be avoided or solved with just some simple changes to the installation process.

Situation Solution
Spanner Bit Snaps During Proper Installation Assuming everything is done right and the bit still snaps, it is likely that the bits are of unacceptable quality. Find a reputable dealer with good reviews and use their bits.
Bits Snapping in Hardwood Applications When using harder materials, a spanner screw must have a pilot hole drilled into the material. The bits are not going to be able to provide that much force before failing. The same is true for knots in wood.
Hitting the second material (if harder) If the second material is much harder than the first (attaching wood to metal for example) when the screw hits the second material, it will require more force to drive through and snap. To prevent this, drill a pilot hole.
Wrong Screw Type The screw type is often wrongly chosen for an application. This can cause poor performance while driving and increase force on the bit. Make sure to use the correct screw type for your application.
Driving the screw below the surface of the material When driving a screw, once the head presses against the material, it will greatly increase the friction on the screw. To drive the screw further, the amount of force on the bit will dramatically increase. To solve this problem, countersink the hole before installing the screw if you want the head to be below the surface.
Proper Drilling Technique Make sure you keep your drill straight when installing the screw, especially with spanner bits. Since there are only two points of contact, both need to share the weight evenly. Make sure to apply steady pressure and keep the drill straight, not angled to the fastener.

Spanner Bits: Worth It?

Over-all, spanner security bits are a great drive style and can make it very difficult, if not impossible, to remove without the proper bit. This makes them a common choice for applications that are open to the public without monitoring such as bathrooms or outside art exhibits. *While security drive styles are less likely to be tampered with, it is still easy to get the drives online. Even though they are readily available, the likelihood of tampering is still greatly reduced by using them.

Shope Spanner Bits

How to Prevent Your Spanner Bits From Breaking | Fasteners 101

How to Prevent Your Spanner Bits From Breaking | Fasteners 101
Transcript

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Bob: Welcome back to Albany County Fasteners – Fasteners 101. I’m Bob and today I’m going to demonstrate installing sheet metal screws with a spanner bit and a spanner screw snake eye screw.

Several different names for these out there. We do get some complaints from buyers saying they snapped the bits. In several situations, you could snap a bit. However, if you use it properly you will not snap the bit.

Some applications where you would possibly snap a bit: 1 – Going into hardwood without pre-drilling. If you go into hard wood and you don’t pre-drill and you just try to drive the sheet metal screw into the wood, chances are you will snap the bit or you’ll snap the screw. Either one could happen. I can drive this screw into this soft wood, which is a 2×4, with no issues of snapping a bit and remove it. I’m gonna demonstrate that.

Another way to snap a bit would be running it into a material and then on the back end there’s some metal that the screw cannot go through and you’re trying and you get an immediate stop in the screw. That will snap a bit.

There’s only two teeth on one of these spanner drivers and, of course, they can snap. It’s not the perfect world with these type of bits. Not like a Torx driver or something along those lines. Where they’re very hard to strip out or snap.

So I’m going to demonstrate, right now, installing this and it’s always important to make sure that your bit is square to the screw and the wood so you have positive contact. Put your hand on the back of the drill and you’ll see, I’m just driving it in with no problem. It’ll suck it in and now I just snapped it and why did I snap it?

I snapped it because the head is countersunk, and the screw came to a stopping point. So those who are snapping bits that would give you a reason so you can see here the bit is snapped. I can’t use that bit anymore.

If you’re driving a screw and a natural piece of wood and not over-torqueing it, you should have absolutely no problems with the bits. It doesn’t matter the quality of the bit. You will still snap the bit if you enter that type of situation.

How To Avoid Breaking Spanner Bits

Avoid Breaking Spanner Bits

Broken Spanner Bit

The spanner drive style is still an uncommon drive style for most people to just have lying around.

This uncommon bit makes screws more resistant to tampering and removal without the proper bit. Due to this, a spanner bit is often referred to as a “tamper-proof” or “security” bit.

The Problem With Spanner Bits

As great as spanner “snake eye” bits are for adding security to an assembly, they also have some downfalls. Spanner bits are made to fit a very specific drive size. If they are used with the wrong size it becomes increasingly likely that the bit will break.

Spanner bits are also more prone to snapping than any other bit type. The spanner bit has two prongs that are inserted into two holes in the head of the screw. Pressure is then directly applied to only those two prongs (across a very small area) which causes the screw to turn. Other bits can have as many as six sides pushing on the head making it less likely that they will break by spreading the load across multiple points of contact.

Spanner bits are commonly avoided for this reason but there are actually a few easy steps you can take to avoid most of the common reasons spanners break.



Steps To Avoid Breaking Spanner Bits

Always Pre-Drill Into Hardwood

Hardwood can be particularly difficult for screws to cut into. We recommend pre-drilling a pilot hole even when the screw has a self-drilling tip. Pre-drilling a hole removes much of the wood that would be in the way and allows a screw to more easily install.

Avoid Coming To A Hard Stop

Drilling into knots or using a screw that is too long where it can hit metal on the back of the installation surface can cause the screw to seize in place. This sudden seizure will place all of the pressure upon the bit prongs and more than likely cause them to snap.

Avoid Over-Installation (Over-Torquing) Of The Screw

When installing the screw, make sure to stop once the head reaches the installation material. Attempting to screw the fastener in further will increase the amount of torque required to turn the screw dramatically.


Watch As Bob demonstrates this with one of our own spanner bits.

*No spanner bit regardless of quality will stay in tact if you do not take care when installing spanner drive screws. It’s the nature of the bit design.

What are Security Screws?

What are Tamper Proof Screws?

Tamper Proof, Tamper Resistant and Security Screws

Tamper Proof Fasteners are screws, Nuts and Bolts best characterized by their unconventional drive style. Tamper Proof Fasteners are used in areas where an assembly is accessible to the public, as a means to deter or prevent vandalism or disassembly. Tamper proof security screws, or Tamper resistant security screws, are distinguished by having an unconventional drive, making tampering with the screw more difficult, if not impossible without the matching driver. Security Screws are used for securing materials from being tampered with, such as gutters, license plates, grills in jails, schools, boats and cars. They are also used in food prep and processing areas. You will often see security screws used in bathroom stalls, particularly toilet partitions and other public locations.



What is an “Unconventional Drive Style”?

Unconventional Drive Styles come in many varieties, but all share one common goal: difficult (if not impossible) installation or removal without the corresponding security Bit or Driver.

One Way Screws

Stainless Steel One Way Screws

One Way Screws (sometimes called Irreversible Screws or One Direction Screws) get their name because of their drive style. The head of the screw features a slotted drive that is designed to instantly cause cam out if the driver is turned in the wrong direction. This is achieved by manufacturing the drive in quadrants that are gradually raised to accept the driver bit when turning the screw right, and reject it when turning the screw left. The One Way drive makes installation of the screws easy, requiring only a standard slotted bit, but removal of the screw difficult (if not impossible) without the corresponding bit or a specifically designed removal tool.

One Way Screws are commonly seen in public areas such as bathroom fixtures and partitions, license plate frames on cars, wall or floor mounted safes, and wherever tampering after installation becomes a security issue. Generally speaking, all Tamper Proof Screws are used to deter vandalism or theft because the removal of the screw is difficult, if not impossible, without the corresponding unconventional bit. One Way Screws are particularly difficult to remove, which means that they should be used for long-lasting applications.

Shop Stainless Steel One Way Screws

Spanner (Snake Eye) Security Screws

Stainless Steel Spanner Screws

Tamper Proof Spanner or “Snake Eye” security screws are installed using a spanner bit. Spanner Screws are commonly referred to as “Snake Eye” because of the two dot drive system. Spanner security screws are used for securing materials from being tampered with, such as gutters, license plates, grills in jails, schools, boats and cars. They are also used in food prep and processing areas. You will often see security screws used in bathroom stalls and other public locations. Spanner screws can only be installed or removed with a spanner bit, which fits a pin into each of the screw’s two drive holes. Since Spanner screws can only be installed or removed through spanner bits, they are very resistant to tampering.

Shop Stainless Steel Spanner “Snake Eye” Screws & Bits

Torx (6 Lobe with Pin) Security Screws

Stainless Steel Torx Screws

Torx® with pin security drive can only be driven with security bits and are used to prevent tampering and theft. Security Screws in this variety are characterized by the 6 lobe, or star drive with a central pin. The pin grants additional tamper resistance as it prevents conventional screwdrivers and grabbing devices from tampering with the original installation.

Shop Stainless Steel Torx Tamper Proof Screws, Bits & Drivers

Tri-Groove Security Nuts

T Groove Nuts

Tri Groove security nuts feature a tapered diameter, making the nuts resistant to gripping devices. Security nuts are installed using a special Tri-Groove socket, which grips the indentations along the outside of the fastener to turn the nut along a thread. Tri Groove nuts are also referred to as T Groove, Trident Drive and Cone Trident Drive Nuts are tamper resistant.

Shop Tri-Groove Nuts & Drivers



In This Video:

Our Fastener Expert goes over many of the popular security fasteners available for your builds.


For more information on Tamper Proof Fasteners and to shop our selection click here.

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