What is a Hinge Cup
A hinge cup is a depression within a cabinet required for the setting of certain invisible hinges. You may also hear this element referred to as a cup hinge or as a Euro hinge. The hinge cup - along with the arm and the mounting plate - serves as one of the three pieces that make up an invisible hinge.
The way a cabinetmaker adds a hinge cup to a cabinet is determined in part by whether its door will feature a profiled edge. If so, that cabinetmaker must be certain that the router bit will not cut into the circumference of the cup. The hole drilled to set the hinge cup must be flat-bottomed and created in the back of the cabinet door; in drilling, the cabinetmaker must be certain to not break through the beveled edge of said door. While the exact location and depth of the hole can vary from manufacturer to manufacturer, the depth usually remains steady across brands at 35 millimeters.