Below is a list of Piano Hinges manufacturers from St. Paul, Minnesota. Piano hinges, also known as continuous hinges, are jointed devices that allow an attached part, like a door or window, to swing. Able to provide consistency in strength along the entire length of the hinge, piano hinges support the objects to which they are attached and reduce the gap between the objects and the hinges. Piano hinges are typically longer than standard hinges, usually measuring five inches in length or more, and often span the length of a joint.