The idea of using pliers to grip onto things has been around for a long time. It's speculated that pliers were first used over 3000 years ago when they were used to handle hot objects, either putting things into or removing them from a fire. Even with all those years between then and now, the concept of pliers hasn't really changed much from the original (although "pliers" used to handle hot objects today are commonly called tongs). Pliers still consist of a pair of handles with jaws on one end (where the gripping or cutting action takes place), joined together at a single pivot point. It's highly unlikely you actually spend any time thinking about it, but pliers work through the direct application of elementary Physics. Each of the arms acts as a "first class lever" (where the fulcrum of the lever is located between the Input force and the output force). This lever action provides a mechanical advantage enabling the user to apply more force than they ever could just using their hands alone.
Today top quality pliers are usually made from high quality hardened steel that's made into pliers through a process called drop forging. (A manufacturing process where hot metal is literally hammered into forms - the heating process improves the strength of the metal by aligning the molecular structure). The arms are then machined to fine tolerances and polished to a bright shine.
Although there are literally hundreds of designs for pliers, all designs fall into one of two broad categories - either slip joint or solid jointed. With slip joint pliers the joint or pivot point is variable and allows for two (or more) width openings so the pliers can be adjusted to the size of the object being held. With solid joint pliers the pivot point is fixed, thus the opening size is also fixed. Since the pivot point in fixed joint pliers is not variable, by design they are able to provide more squeezing/holding pressure so are less adaptable than slip joint pliers and are best suited for a single function
Some common slip joint pliers:
- Regular slip joint pliers are a fixture in all sets of pliers. These are general utility pliers that have a jaw opening that can be adjusted to one of two opening widths to grip onto various sized objects.
- Water pump/groove joint pliers (also commonly called "Channel locks" based on the brand name of a manufacturer). These can have up to 8 different positions so they can be used on many different sized jobs plus the teeth are positioned so they give a firm grip on round objects.
- Plumber's pliers usually have a soft plastic covering on the teeth in the jaws so they won't mark decorative plumbing fixtures.
Fixed joint pliers since they can provide a lot of force are commonly used as cutting pliers in one of three designs:
- Side cutters, have their cutting blade on one side only.
- End cutters or "nippers" have their cutting surfaces on the end of the arms and are used to make cuts close to the surface.
- Diagonal cutters (or dags) have their cutting surfaces set diagonally to the pivot point
A Few Specialty PliersNeedle nose: Have long thin arms that allow you to reach into small narrow openings. The fixed pivot point gives them a strong secure grip on anything the jaws are closed on. The narrow point makes them extremely useful for doing electrical wiring work (they make it easy to wrap a wire around a terminal).
Locking pliers (commonly called Vice grips): Have a fixed pivot point, but the opening size is adjustable and they can be locked onto an object (or objects) leaving both hands free to do other work or providing a great amount of turning power. Locking pliers are very versatile and can be used in place of pipe wrenches, adjustable wrenches, ratchet wrenches or even clamps. For even more specialized applications they're also available with various shaped jaws including thin nose, curved or even with even wide flat jaws.
Linesman pliers: Very strong heavy-duty pliers usually with a side cutter built in.
Wire stripping pliers They have various sized openings in the jaws so they can strip the insulation off a wire without cutting the wire itself.
Bolt cutters: Used for cutting metal bolts or rods that can be more than 1/2" think. Made from high quality steel with long handles (up to 42") that provide great leverage for cutting through solid metal rods.
All the types of pliers we've listed here are only a few of the many available at your home store. No matter what your application you can bet there will be a set of pliers that have been specially designed to make your job easier.