What Is a Butt Hinge? The Basics of Butt Hinges and How They Work


Butt hinge by Monroe Engineering

Hinges are one of the most common types of mechanical bearings. As you may know, they are used to provide a limited angle of rotation between two objects. Hinges consist of two leafs and a knuckle. A pin is inserted through the knuckle to hold the leafs together. Butt hinges follow this same design, but they are distinguished by other hinges with their mortised construction.

What Is a Butt Hinge?

Also known as a mortise hinge, a butt hinge is a type of hinge with a pair of identical leafs. They typically feature a larger knuckle than other types of hinges. With their wide knuckle, the two leafs will sit flush with each other when the butt hinge is closed.

How Butt Hinges Work

Butt hinges work like most other hinges. They provide a limited angle of rotation between two objects. One leaf is connected to the fixed object, whereas the other leaf is connected to the rotating object (e.g. a door). Butt hinges have a knuckle between the two leafs. This knuckle allows them to rotate. You can open the rotating object by pulling it away from the fixed object.

Butt hinges are installed with threaded fastners. The leafs must be installed on the two objects with a set of threaded fasteners, such as screws. The knuckle, on the other hand, requires a pin. The pin may be fixed, or it may be removable.

Butt Hinges vs Other Hinges

The main difference between butt hinges and other types of hinges is that the former are designed to sit flush when installed, whereas the latter are not. Butt hinges are installed in recessed surfaces. A recess is cut out of the rotating object and the fixed object. The two leafs of a butt hinge are then installed in these recessed.

When the rotating object is closed, the two leafs of a butt hinge will remain flush with each other. The only part of the butt hinge that will be exposed will be the knuckle. The leafs of other types of hinges, conversely, may or may not sit flush with each other. Some of them may be exposed when the hinge is closed

Butt hinges can typically accommodate heavier objects than other types of hinges. They feature a larger knuckle than that of other types. The knuckle, of course, is the bearing that holds the two leafs together. With their large knuckle, butt hinges can accommodate heavier objects than other types of hinges.

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