Beam Compass Jig for router

Design by Ed Falk

Here are two photos of a jig I built for my router in less than half an hour. The two 1/4" threaded rods screw into the router base (they come from another off-the-shelf jig.) The wooden block is just some random piece of hardwood scrap (I don't even know the dimensions.)

First, cut a block of wood long enough to accommodate the distance between the threaded rods, plus enough room for threaded inserts at each end.

  1. Drill two 17/64" holes horizontally through the block to accommodate the threaded rods.
  2. Drill a 1/4" hole vertically through the center of the block to accommodate a dowel
  3. Drill a larger hole vertically a short depth into the bottom. This allows the jig to accommodate a dowel centering pin (see photo 2) as well as a dowel.
  4. Drill two holes into the ends to meet the rod holes. These are sized to accept your threaded inserts.
  5. Insert threaded inserts at the ends. Put thumb screws into the threaded inserts.

Crude 2-view drawing:

First picture shows jig in use. There is a dowel through the jig and the work below. Use this method if the center of the piece to be cut out is waste.
Second picture is a close-up of the jig, shown upside-down. Dowel has been replaced by a dowel-centering pin. Use this method to avoid drilling through the workpiece.
Third picture shows the finished part. this was the upper tube assembly of the Miatascope.