A hinge cup is a recess that is necessary for installing specific types of invisible hinges. While the terms hinge cup, cup hinge, Euro hinge, and invisible hinge are often used interchangeably, there are some slight differences. The hinge cup is a component of the invisible hinge that, along with the arm, makes up the movable half of the door mechanism. The complementary piece to a hinge cup is known as a mounting plate.
When installing the hinge cup, it is crucial to determine if the cabinet door will have a profiled edge. If so, it is important to ensure that the router bit does not cut into the circumference of the cup. The hole drilled to set the hinge cup should be a flat-bottom hole drilled into the back of the cabinet door, and it is equally important to ensure that this drilling will not break through to the beveled edge of the door. The diameter of the hole will generally be 35mm, although the location and depth of the hole may vary slightly depending on the brand.