After everything has cured, draw the outline of the inside edge of the spacer block. Also mark the location of the INSIDE edge of the pipe tunnel. Lastly, place your gear halves on top of the block and mark the edges of your gear block. You'll notice how close the pipe tunnel edge and the edge of the gear are: you'll have to dead center it with a drill later.

Now drill through the entire block at the center location of the spacer blocks, 4 across the front and 4 across the rear with a 3/32" drill. Be mindful of where your edges and pipe tunnel are, you don't want a head in the way! These are your pins, you will use #4x3/4" button head sheet metal screws. Install these screws with 2 hour epoxy (or just slow cure) but be sure and wipe off the excess epoxy. The points will barely protrude from the other side, but who cares, you can grind them flush if you wish.

(cont)