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If you take apart military or aircraft equipment, you are likely to come across bolts fastened together with twisted wire. And the twisting on the wire is so perfect that you might think it is done by a machine. But the truth is that those twists are done by hand using a special wire twisting tool. This tool is called safety wire pliers or lock wire pliers.
Sometimes though, duckbill pliers can be used to twist wire although they don’t produce as crisp wire twists as lock wire pliers do. They are also not as efficient but they do the job. If you would like to learn more about duckbills, check out this article on duckbill pliers and their uses.
In this article, I share more about lock wire pliers and why they are the best for twisting safety wires.
Table of Content
What are safety wire pliers?
Safety wire pliers or lock wire pliers are a special type of pliers for twisting safety wire to secure critical fasteners. They have jaws and handles like regular pliers but one of the handles is fixed to a center barrel. The center barrel houses the twisting mechanism and the jaw locking mechanism. The pliers were invented by inventor Barry J. Harrison and co.
Safety wire pliers are the best for making repeatable lock wire twists. When using them to twist wires, start by sliding the locking sleeve on the center barrel to lock the jaws onto the wires. Then pull the knob at the back of the barrel to twist the pliers. You can repeat the process until you get the correct number of twists per inch on your wire.
How to use safety wire pliers
As I mentioned, safety wire pliers are the most reliable for lock wiring. They make twisting safety wire an effortless exercise. To use these pliers in your project, simply follow these simple steps:
- Put the safety wire through the fastener or around the component you want to secure.
- Center the wire and grip both ends at an appropriate distance from the fastener or object.
- Slide the sleeve on the center barrel to lock the pliers onto the wires.
- Release the pliers and pull the knob on the center barrel to rotate the pliers.
- After every pull, hold the pliers with one hand and release the knob to allow the spring on the twisting mechanism to retract.
- Repeat this until you get the desired twists per inch.
- Pull back the locking sleeve to release the jaws.
- Use the integrated cutters to cut the newly twisted wire to size.
Factors to consider when shopping for lock wire pliers
It is possible to get it all wrong when shopping for safety wire twisting pliers. But with this guide, you can be sure to get a tool that ticks all the right boxes. So, these are the factors to consider when choosing the best safety pliers for your trade.
Jaw locking mechanism
Good wire twister pliers must have a locking mechanism to lock the jaws onto the wire. This allows you to release the pliers and use the pull knob to twist the pliers automatically. The locking feature is one of the core components of lock wire pliers.
Integrated wire cutters
When installing safety lock wires, you need to cut them to size after twisting. As such, you might need a pair of wire cutters along with your wire twisting tool. But isn’t better if your lock wire pliers have integrated cutters so that you won’t have to change between tools?
Safety wire pliers with cutters are very handy. They make easy the work of twisting and cutting safety wire. Instead of wasting time swapping between wire cutters and wire twisters, lockwire pliers with cutters do all the work. But you must make sure that the cutters are strong and sharp enough to cut single and twisted lock wire. Otherwise, you may still need to keep a good pair of dykes at hand.
Safety wire pliers come in various sizes for different wire sizes. When selecting the best pliers for your work, you must make sure they are rated for the size of wire you intend to use. If you use small pliers to twist large safety wire, you may not get a good grip on the wire and the twists will not be that great. On the other hand, if you use large pliers to twist thin safety wires, you may break them when twisting or gripping. So, it is good to match the size of pliers with the size of wire.
A rule of thumb is that small safety wire pliers (about 6″) are suitable for small wire sizes like 0.020″, 0.025″ & 0.032″. On the other hand, larger safety pliers (above 6″) work great with bigger safety wires such as 0.041″ and 0.052″. However, you can still use the large pliers on thinner wires from 0.020″ and above but with caution.
One advantage of small safety wire pliers is they are good for getting into tight spaces. So, depending on the nature of your project, you can find the size that best meets your needs. Otherwise, if you just purchase safety pliers without taking into consideration the size of wire you will be using or the workspace, you may end up with a tool that will not do the job effectively.
I do not like to reuse safety wire but sometimes when I start the twist the wrong way, I prefer to undo it instead of discarding the wire. But undoing a twist by hand can be tedious. That is why reversible safety wire pliers are handy.
They have a switch on the barrel for reversing the direction the pliers spin. You can switch the direction from clockwise to anticlockwise and vice versa. So, if you want to undo a twist with reversible lockwire pliers, you just flip the switch and the pliers will rotate in the reverse direction when you pull the knob.
Another instance where you would need safety pliers with reversible action is when safety wiring three bolts together. From the first bolt to the second bolt, you twist the wire clockwise, and from the second to the third bolt, the twists go counterclockwise. With reversible wire twister pliers, twisting wire in the opposite direction is easy as flipping the reverse switch. They make the process so much easier.
In a nutshell, if you don’t like to waste your safety wire, you may want reversible lock wire pliers for undoing twists. Also, if you are an aviation or race car mechanic, you will appreciate the reversible action on your lockwire pliers when safety locking bolts.
Best Safety Wire Pliers
Stahlwille Wire Twisting Pliers (6575 1 220) – Best Overall
- Length 9″
- Reversible action
- Can twist up to 0.06″
- Made in Germany
The Stahlwille safety wire pliers are the best you can buy with money. They are made in Germany and well-built just like many other German tools. The pliers have all the features you would desire on a good wire twister. They feature a reverse action that lets you choose which direction to twist wire. To set the direction, you simply toggle the small switch on the barrel to the front or back.
The Stahlwille safety wire pliers are all metal. They are made from chrome vanadium steel that is strong and resistant to rust. The jaws are serrated to provide a positive grip for clamping on the wires tight ready for a spin. Furthermore, the integrated side cutters eliminate the need to carry a separate pair of wire cutters.
What is more fascinating about these pliers is the quality of finish and how they feel in the hands. Not to mention their silky smooth twisting mechanism. Indeed, the Stahlwille lockwire pliers are a dream come true for any mechanic who safety wires mechanical parts, especially in aviation where precision and accuracy are paramount.
So, if you work with lockwire daily, there is no reason these heavy duty Stahlwille lockwire pliers from Germany shouldn’t be in your toolbox. Yes, they come at a premium cost but they are worth every dime.
The Stahlwille safety wire pliers come in two nominal sizes; the 9″ (230mm) and the 11″ (280mm). But the 9-inch pliers are the most ideal because they can twist wires as thick as 0.06″ with ease.
BikeMaster 6″ Safety Wire Pliers (15-1554) – Best Bang for the Buck
- Length: 6″
- Works with safety wire up to 0.042
- No reversible action
- Includes a 25′ 0.032″ stainless steel safety wire
In my opinion, the BikeMaster are military-grade safety wire pliers at a bargain. They are forged from stainless steel and measure 6 inches long excluding the center barrel. The overall length is 7inch from the tip of the jaw to the back of the barrel. The pliers have a nice red anodic oxide finish that makes them so sleek and attractive.
BikeMaster pliers are solid, well fabricated, and have a sturdy locking mechanism. The jaws clamp together nicely to grip wires while the spinning action works so smoothly to braid the wires. The pliers are great for twisting small wires of up to 0.032″ in diameter. They are also great for working in tight spaces. But if you are working with larger wire (say up to 0.042″) and you have more working room, I would recommend you go for 9″ BikeMaster pliers. They are built the same except that they are larger for working with larger wire. Both pliers have integrated side cutters for cutting safety wire to size.
The only problem with Bikemaster safety pliers is that they only spin in one direction. In other words, they do not have a reversible action. So, if you are safety locking bolts, you would need to twist the pliers manually in the opposite direction.
Other than that, the 6-inch Bikemaster 15-1554 lockwire pliers are excellent for installing safety wire on various industrial and personal projects. You can use them for home, workshop, or light-duty industrial applications such as aircraft maintenance and motorsport repair. They are a nice addition to a racer or mechanic’s toolbox. The only reason I do not recommend them for heavy-duty use is the lack of a reverse action feature.
Milbar 41W Lockwire Pliers – Best for mechanics
- Length: 9″
- Has a reversible action
- Works with .020 to .051 safety wire
- Made in USA
Milbar is a US brand that makes some of the leading safety wire pliers for professional use. The Milbar wire twisters come in various shapes and sizes and the 41W model is one of the best. It measures 9″ long and features a reversible action for left and right twists. The locking sleeve on the pliers has an automatic spring return. When you press the locked handles together strongly, the spring retracts to open them.
The most important feature of the Milbar pliers is the reverse action. It lets you spin the pliers in both directions to braid wires either clockwise or counterclockwise. To switch from forward to reverse, you simply turn the sleeve between the pull knob and the barrel to the left and vice versa.
What is quite disappointing, though, about the Milbar 41W lockwire pliers is the plastic part on the center barrel. Although it makes the pliers less heavy in your hands, I doubt it would hold up well to impact if you drop the pliers repeatedly in the workshop.
Nevertheless, the other parts are made from hardened steel. The jaws are knurled to grip wires tightly without marring them. The pliers also have sharp integrated cutters that cut safety wires of different sizes like butter. But if you plan to use the pliers to safety wire parts on an aircraft, I recommend the cushion-throated version of these pliers. The model number is 25W. The pliers are similar to the 41W model except that they have a cushion throat for catching clipped wire ends to keep them from falling into the wrong places and causing foreign object damage (FOB).
Frequently Asked Questions (FAQs)
When using safety wire pliers, the most important precaution you should take is to wear safety goggles. They protect your eyes from wire pieces that may fly at your face when you nip off twisted lockwire.
Safety wire pliers are the best for twisting lockwire but when working in odd or awkward positions, twisting the wire by hand may be easier. Only then are lockwire pliers difficult to use.
Don’t be lied to! Safety wire pliers are not bad even though in the army you will be encouraged to twist safety wire by hand despite being trained to use wire twisting pliers. The reason the commander will tell that is so that you do not waste time waiting for the shared wire twisting pliers. Otherwise, if everyone had their own lockwire pliers, no one would make you think the pliers are bad. In any case, twisting safety wire without a tool is more dangerous.
The cushion on the jaws of some wire twisting pliers is for catching wire clippings so that they do not end up in the wrong place and cause problems. Safety wire pliers with cushion throat are very useful in aviation maintenance.
The difference between safety wire and safety cable is that safety wire or lock wire is twisted around fasteners whilst safety cable comes pre-twisted. Also, lockwire is terminated by twisting around a fastener to form a pigtail while safety cables use ferrules for termination. That being said, both devices serve the same purpose of constraining threaded fasteners to prevent unintentional rotation. Find out more about safety wire vs safety cable in this white paper.