The fence sits underneath the templates and is used to register the jig against the back of the box and securely clamp the jig to the box. The Soss 203 requires a 1/8” space between the back of the hinge and the back of the box. Since the hinge is 1/2”, the centerline of the hinge must be 3/8” from the back. It is important that the fence be square to the template otherwise the hinges, hence the box lid, will be crooked. I cut a piece of 3/4” plywood about the width of the templates, drilled through holes, and inserted threaded nuts. Here’s how I set the fence.
I clamped a piece of scrap wood in the bench clamp and used a 3/8” brass bar to mark the centerline of the hinge on the bench.
Then I lined up the centerline of the jig to that line and used the clamp to gently press the jig’s fence against the bench before tightening the bolts that hold the fence in place. You don’t want to tighten the clamp too much. Just enough to press the fence against the bench. And that’s it. The fence is perfectly fitted to the jig.
I place the scrap wood back into the clamp, drew a centeline across the piece, and clampled the jig in place.
To make the first mortise cut, which is the top mortise for the hinge, you zero out the bit onto the surface of the part being cut and use the hinge itself to set the router’s depth gauge. I like to use long bits for mortises, but I think a regular length bit should still work. I like to first make a series of plunge cuts then clean out the waste.
After the first cut I vacuum out the mortise and flip the other half of the jig in place to cut the second mortise.
Same procedure as before. I first zero out the bit then I use a scrap piece to set the depth gauge. Note, in this step I am zeroing out the bit into the bottom of the first mortise so I only have to cut another 1/2” plus a shade deeper (IOWs, the total hinge depth is 3/4”, 1/4” top mortise and another 1/2” for the bottom).
And here’s the result in the scrap piece with no adjustments. Note, particle board like plywood is much softer than most of the hardwoods we use so a hinge which may have a snug fit in the scrap wood may be slightly too big in the actual hardwood. The jig is easy to adjust with a file and sandpaper. If the mortise is too big you can apply tape to the ends as a shim.
I hope this series has been beneficial. If you have any comments or suggestions on the blog or improvements for the jig please let me know.
-- tim hill www.newcalshop.com