Cannon Plug Pliers, Why Do You Need Them?

Cannon plug pliers have soft non-marring jaws for gripping sensitive workpieces. Read this article to learn why you need them in your toolbox

Sometimes Cannon plug electrical connectors or sensitive plumbing fixtures and fittings can be too tight to loosen by hand. Worse, you cannot use regular pliers because they will bite into the material and damage the surface. So, what do you do to grip such sensitive workpieces with pliers without marring their surface?

How to Grip Delicate Workpieces with Pliers

There are three things you can do to grip a delicate workpiece with pliers without marring or scratching its surface.

Option 1: Use a piece of cloth between the workpiece and the pliers.

The cloth or rug will prevent the serrated jaws from scratching the sensitive workpiece.

Alternatively, if you have old leather gloves that you don’t use, you can cut off two finger sleeves and slide them over the pliers jaws. They will give you what Ron Hazelton calls, “a steel grip, with a velvet touch“.

Option 2: Use rubber jaw covers

These are rubber sleeves that fit on the jaws of pliers to cover the marring teeth. They help convert regular pliers into soft jaw pliers. Unfortunately, not all types of pliers have jaw-protector sleeves. Moreso, jaw protector sleeves are not universal. They are designed for specific pliers models and sizes.

Option 3: Use Cannon plug pliers

Cannon plug pliers are the most professional type of pliers for gripping delicate and sensitive workpieces without mangling them or leaving surface scratches.

What are Cannon Plug Pliers?

They are a special type of adjustable pliers with soft plastic jaw inserts for gripping fragile objects such as cannon plugs, chrome-plated pipes and fittings without damaging them. These pliers provide a firm grip on an object and don’t mar its surface.

Unlike regular water pump pliers that typically have V-style jaws, most Cannon plug pliers have curved jaws with a groove in the middle for inserting the jaw padding. Some manufacturers use set screws or pins to keep the padding from moving or coming off. This extra reinforcement on the padding is important, especially when twisting the pliers hard.

Jaw inserts for most cannon plug pliers are replaceable. That’s why manufacturers use set screws or pins that are easy to remove and install.

You can purchase the exact same replacement inserts or upgrades. However, mindful manufacturers will always try to improve the effectiveness of their cannon plug pliers by upgrading the quality of the jaw inserts.

For instance, when Knipex Tools learned that the first version of plastic inserts slipped on smooth workpieces, they released new multi-component jaw inserts with softer parts that created more friction to minimize slippage.

Uses of Cannon Plug Pliers

Cannon plug pliers were initially designed for removing stuck Cannon plug connectors in aircraft but now plumbers also use them to grip sensitive plumbing fixtures and fittings that can easily get marred by regular pliers.

They use them as plumbing wrenches to gently clamp polished kitchen and bathroom faucets, sink plumbing, faucet aerators, ornamental fixtures, and all other delicate fixtures.

Soft jaw pliers are also great for breaking loose tight plastic nuts and PVC traps under the sink.

In the aviation industry, Cannon plug pliers are a must-have tool for loosening tight Cannon plug connectors in aircraft. They help to multiply the grip strength of your hand while protecting the circular connectors from surface scratches and damages that can corrode or rust and affect degrade the connector. A damaged aviation plug connector can compromise the integrity of the electrical connection and result in catastrophic failure.

If you are in the aircraft industry, military, or navy, you know that Cannon plugs are the best electrical connectors for extreme environments. They not only make the wiring neat but also offer the safest electrical connection solution. Not to mention, Cannon plugs are easy to connect and disconnect. They are not like regular crimps.

Cannon plugs have multiple pins which terminate electrical wires that connect to various functions in a system. For instance, because aircraft are highly modularized, electrical wires from each module are bundled together and terminated to a Cannon plug connector which connects them to the wiring backbone of the aircraft. The same applies to navy ships, luxury yachts, and high-end automobiles that use cannon plugs.

How Cannon Plugs work

how cannon plugs work
Cannon plug assembly parts

Cannon plugs have a male and female connector which mate together to create an electrical connection. And as I mentioned, a cannon connector can have one pin or as many as 48 pins or even.

A Cannon plug has a collar that binds the male and female connectors to keep them from separating. You can tighten the collar by hand, which can be difficult when you want it to be snug and tight, especially in vibration-prone areas.

Similarly, when you want to disconnect the connector, the cuff can be too tight to undo without a tool. And because you don’t want to damage its surface, you go for Cannon Plug Pliers or soft jaw pliers.

Cannon plug pliers grip the cannon plug cuff firmly without mangling or scratching the surface. They do the same with all other workpieces.

But don’t expect soft jaw pliers to grip as strongly as regular water pump pliers. They are built to be gentle.

Best Cannon Plug Pliers

The following are some of the best cannon plug pliers on the market.

Knipex Cannon Plug Pliers 81 11 250 – Best Overall

knipex cannon plug pliers

Key Features

  • Large grip capacity: 0.5 – 2.75 inches
  • Length: 10 inches
  • 25 fine adjustment position
  • Replaceable plastic jaws
  • Lifetime Warranty
  • Made in Germany

The Knipex 81 11 250 is much the same as the Knipex Cobra. The only difference is the jaw style. Unlike the cobras which have V-shaped jaws, these Cannon plug pliers from Knipex have nicely curved jaws with soft plastic inserts.

They use the same button adjustment style with 25 grooves that allow you to adjust the grip capacity between 10mm to 70mm.

These pliers have a box joint design and boast the same quality as other Knipex pliers.

new Knipex multi-component jaw inserts
New Plastic Jaws

The best thing about Knipex precision soft jaw pliers is that they come with soft plastic jaw inserts that grip with minimal slip. And if you don’t like how they grip, you can replace the inserts with the newer multi-components paddings that have rubbery material for better grip.

The inserts are easy to remove. You just undo the screw on each jaw from the outside and you are good to go. To install new inserts, just put them inside the groove on the jaw and fasten them with screws. Make sure they fit properly inside the groove for best results.

Although the nylon bushings do not cover the entire jaw, they are thick enough to prevent your workpiece from coming into contact with the uncovered section.

These Knipex 81 11 250 soft jaw pliers are a must-have for aviation technicians and professional plumbers who often have to deal with connectors and fixtures that require extra care.

Tsunoda WP-300SC-S Soft Jaw Pliers – Best for plastic adapters

tsunoda soft jaw pliers

Key Features

  • Grip capacity: 0.875 – 2.75 inches
  • Length: 12 inches
  • 9 adjustment positions
  • Spring-loaded handles
  • Replaceable nylon jaws
  • Made in Japan

The Tsunoda WP-3000SC-S are another great soft jaw pliers for gripping surfaces that you don’t want to damage. They have soft nylon covers that run across the jaws from end to end.

Unlike the Knipex pliers inserts that are held in with screws, the resin covers on the Tsunoda pliers are not retained by any screws or pins. Instead, they have some juts that fit into the holes on the inside of jaws. This makes them very easy to remove and install.

Unfortunately, the pads tend to come off under great pressure, which affects their usability on workpieces that require more twisting force.

That being said, the Tsunoda water pump pliers with soft jaws do a great job on plastic plumbing fittings because they typically have grooves that prevent slippage and are usually not too tight.

They can grip fittings of sizes 22mm to 70mm in diameter. This is the size range of most PVC nuts and trap adapter fittings for sink drains that use plastic fittings. For instance, the standard sink trap size for a bathroom sink is 1-1/4″ and 1-1/2″ for a kitchen sink.

Mayhew Soft Jaw Pliers 95690 – Best for smooth surfaces

Key Features

  • Maximum jaw width: 2.75 inches
  • Length: 14 inches
  • 8 adjustment positions
  • Spring-loaded handles
  • Made in Japan

The Mayhew Soft jaw pliers are another great adjustable pliers with soft non-marring jaws. They are made in Japan but sold under the Mayhew Company brand in the US.

These pliers are similar to the Tsunoda except that they are more expensive and the nylon inserts do not come off easily unless you undo the #0 Phillips screws holding them in. They also have spring-loaded handles, which are comfortable to work with especially if you have arthritis in the hands.

The Mayhew Cannon plug pliers are 14inch long and can open as wide as 2-3/4 inches. There are 8 adjustment positions you can move the jaw to find the sweet spot for clamping down on your workpiece. However, the slip joint adjustment mechanism is not as smooth as on the Knipex.

These Mayhew Soft jaw pliers come with two sets of interchangeable jaws. You can use them to do any work for which cannon plug pliers are made. This includes loosening or tightening cannon plugs, plated pipes/fittings, camera lenses, PVC plumbing and irrigation adapter kits, etc.


There you have it. That’s all you need to know about Cannon plug pliers and their uses. In summary, Cannon plug pliers, multiply the grip strength of your hand, just like water pump pliers, but they have soft jaws that allow you to grip a workpiece without marring the surface.

These pliers are great for grabbing round sensitive workpieces such as Cannon plugs, chrome pipes, brass fittings, and PVC pipes and adapter fittings. They have circular padded jaws that provide maximum contact on the workpiece without damaging the surface. The best thing is that the jaw inserts are replaceable. You can change them when they wear out or when there is a new release.

You should keep them in your toolbox if you are a plumber, aviation technician, or just a homeowner who likes fixing things around the house. Even woodworkers who do woodturning may find Cannon plug pliers useful for clamping down on wood pieces they don’t want damage with regular pliers.

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Julio a.k.a Pliersman is the owner and creator of the Pliersman Website. A blog that informs and educates you about different types of pliers and their uses. Julio is a handy person and has used a variety of pliers including general-purpose and specialty pliers to accomplish tasks. He holds an electrical engineering degree and has previously worked as an O&M manager for minigrids where his love story with pliers and other tools began.