I’ve never worked with butler hinges before. They are designed to have positive stops at 90 degrees and also at 180 degrees. Because of this, there is a pretty strong leaf spring on the underside. This makes for a very irregular surface to mortise in! I didn’t get it right on my first attempt, and so I ripped away the failed part of the surface and edge-glued another fresh piece onto the table surface I was making. Here’s a pic of the underside of a butler hinge: As you can see, there is a bevel and spring and other irregularities, and I wanted to be sure that the two hinges were bedded down into the surface with optimum contact between brass and wood. What to do? I bought some modeling clay at the dollar store, wax paper, and pressed the hinge into the softened clay with the bench vise! After a few false starts, (think: Edison!) I was finally able to achieve a perfect female impression of the underside of the hinge! From this I could visualize what the mortise should look like on the surface of the table: Sorry if the image in the clay is hard to see in the photo! but it was about perfect, and I could measure with my calipers and lay out the exact cut lines to follow with a chisel. Another pic:
Anyway, this is how I approached the solution for getting an exact image to chisel out an irregularly shaped mortise for that specialty hardware I’m using. Bottom pic shows the good snug mortise I achieved with the help of the modeling clay. Positive comments welcome!
-- Einstein: "The intuitive mind is a sacred gift, and the rational mind is a faithful servant. We have created a society that honors the servant and has forgotten the gift." I'm Poopiekat!!