The joint
As the fulcrum, the joint determines the transmission of force applied on the handles to either the cutting edges or gripping jaws of the pliers.
The connection between the two halves of pliers is possible through different designs of the joint; either as a screw, rivet, or forged bolt. The joint is selected depending on the load for which the pliers are designed. Great precision is required to ensure that pliers with a fixed articulation point rotate with just the right amount of ease.
Lap joint
When the two halves of a pair of pliers are connected by a lap joint, normally used for carpenters' pincers, concreters' nippers and high leverage diagonal cutters, they lie on top of each other without being overworked.
Single joint
When constructing a single joint, both parts of the pliers are half cut out. This way the two pliers handles can be placed inside one another and the outer surface of the rivet area is smooth, not jagged.
Box joint
Pliers with box joints are particularly resilient. They are created by having one slotted handle and the other handle is pushed through it. A joint pin mounted on both sides connects the two parts so that the handles are securely guided.
Slip joint
Slip joints allow the gripping jaws of a pair of pliers to be optimally adapted to different workpiece sizes. This is done by shifting the pliers handles towards or away from each other. In order for this to work, a locking mechanism is unlocked by opening the pliers handles further, or a spring-loaded bolt is disengaged for adjustment. Classic examples of pliers with this joint are water pump pliers and pliers wrenches.