In two recent projects, the Copper Patina box and the String Box II, I installed Soss hinges. I had once thought of a way to adapt a regular square hinge jig to make routing the mortises for the Soss hinge easier. It turns out, with this jig, it is very easy, and fast, and accurate. The Secrets of the String Box Revealed blog showed some photos of the jig and described how it works. I’m sure most folks on LJs could see how this was built, but I thought I’d do a more detailed blog to show how. So let’s start at my favorite part, the end.
Here’s what we’d like to achieve, tight fitting hinges that are aligned so that the box and lid are square and flush. The Soss hinge requires eight mortises, four narrow, deep, inside, and four wider, shallow, outside. While the outside or top mortises ideally need to be tight to the hinge, the inside or bottom mortises can be a little larger to provide easier installation. But not so wide that it interferes with the screw holes.
Let’s start by considering the required dimensions of each mortise. The table below shows the mortise size and (my) template groove sizes for the Soss 101 (3/8”) and 203 (1/2”) hinges. Since my templates use a 5/8” guide bushing, just add the difference between the diameter of the bit (i.e. the width of the hinge) and the bushing to the mortise size to figure the template hole size. For example, the Soss 203 hinge requires a top mortise 1 3/4” long and 1/2” wide. Using a 1/2” diameter bit and a 5/8” bushing the difference is 1/8” (i.e. 1/16” on each end), so the template’s guide hole needs to be 1 7/8” long or the 1 3/4” mortise plus 1/8”. There are plenty of sites on the net including Woodcraft, Rockler, etc., that have the dimensions for the hinge you’re using. Just use this table as a concept guide and make the appropriate calculations.
Now that we finished the end, next time we can begin the finish.
-- tim hill www.newcalshop.com