I enjoy the way a project in one area always spawns a variety of sub-projects in all sorts of other areas. Here's a set of 4 hinges I built to hinge the corners of my tympan and frisket frames.
 I'm not sure who invented knife hinges; I first read of them in one of Krenov's books. Indeed, one of his students still makes and sells them. I wanted an especially thin cross section, so decided to make my own. A big advantage of knife hinges is that I can build them myself. Below is one hinge, disassembled into its component parts.
 My hinges are made from rectangular brass bar, 1/4" x 1/8". The pin is turned from 1/4" round stock (the ends are fitted very carefully to the holes; they're about 1/8" diameter). I mounted the hinges using #4 screws.  Here's where the hinges will fit. One pair will join the frisket frame to the tympan frame. The other will support the tympan frame.  Here's how the frisket frame is hinged to the tympan frame.  For the tympan frame, I hinged it to a brass bar, 5/8" square (i.e., furniture high). Bitter experience teaches that the screws holding the hinges to the brass bar should be locked in place with Loctite; otherwise, things get loose and registration is lost.  I put the entire bar and tympan assembly on the bed of the press and lock it up against the taper pins. |