Hidden door hinges – Unlike a normal piece hinges that attach to the side of the door and out of the cabinet frame, two pieces hidden hinges installed on the back of the door and inside the cabinet frame. An extension on the hinge wraps on the cabinet frame and connects the two parts of the hinge together. A “bit Forstner” (found at hardware stores and home) is used to drill a flat, deep hole, 1 1/4 inch in diameter, to the seat hinge in the door.
Place the cabinet door face down and measure 3 inches from the top of the door and 3 cm from the bottom of the door. Mark these positions hinges on the door. Align the tip on the signs of the hidden door hinges, being that the outer edge of the hole will be at least one-quarter inch from the outer vertical edge of the door.
Use a bit ‘Forstner drill to ensure the hole does not go all the way through the door. Drill a 1 1/4-inch in diameter at each location on the door hinge. Do not press down so hard on the drill that is forced through the front door. Put the hidden door hinges into the two holes 1 1/4-inch and fix the door with the screws provided. Align the door opening, wrap the extended part of the hinge on the frame of the three-quarter-inch cabinet, and secure the hinge to the frame with the two 5 x 5/8 inch screws. Use a power screwdriver where space allows.