About Piano Hinges

Hinges are often made of brass or other soft metal.  Their strength comes from their long length and secure fit from many screws to the faces of the hinged materials.  So far so good...

Piano hinges are not made to withstand twisting.  Use a heavy grade of hinge, if possible.  Be sure that the hinge is very securely screwed to the wood so that no twisting gets started--once it starts, the whole thing might collapse.

See also

Forward/Backward Movement of the Copier

The swing box sits on the end of the swing arm.  It connects to the ladder frame by a piano hinge that runs across the rung of the ladder.

swing box hinge