What is a Knife Hinge?

A knife hinge is a flat style of hinge. These cabinet door hinges are typically suited to situations where a semi-concealed hinge is appropriate or desired. The knife hinge has the capability to fully open and allow doors to rest completely flat against the neighboring cabinet without requiring much metal to be visible. This hinge is mortised into the frame and top or bottom edge of a cabinet door for installation. The only visible part of the hinge is usually the pin that is the axis point on which the hinges movement pivots.

Installing a knife hinge can be extremely difficult because of the small amount of margin for error allowed. If the plane of the hinge is slightly askew, then the hinge will not function smoothly. Some manufacturers incorporate a slot screw hole so that minor adjustments can be made to compensate the door’s hang, but the hinge itself is so basic that its two pieces are not very tolerant of misalignment. Some models have full swing capabilities, while others incorporate a stopper. All manufacturers produce both left and right side hinges in this style.