Wenge and Zebrawood Speakers (Curt Campbell's Invictus) #3: Back Panel Construction

329
0
The back panel is very simple.

It has a bunch of holes for the mounting bolts. There was nothing hard about them.

It has a big hole in the bottom for the port. Cutting that was easy with my circle routing jig.



It also has two holes for the binding posts (where you attach the speaker cables). I thought it would take me five minutes to drill them, completing the back panel. But it took some head scratching and several hours.

The Invictus kit from Meniscus includes their Big Posts. They're nice, robust posts, 1/2" in diameter with a 5/16" diameter threaded shaft.

I drilled 5/16" holes for the posts, and I thought I was done. Then I realized I was just starting.

Here's the problem. With the shaft of the post in the hole, the post can still spin freely. A nut on the other side of the panel holds the post in place, but I knew that, no matter how much I tightened that nut, the post was going to spin. I hate posts that spin.



The photo also hints at the solution. There are flats machined into the sides of the post. All I needed to do was cut shallow, racetrack-shaped mortises to hold the bottom part of the posts.

I used my drill press to cut the mortises. I don't have a 5/16" Forstner bit, so I used my 1/4" bit. I set the depth of the press to match the height of the flats, and I drilled a counterbore 1/8" on either side of the center through hole.

This photo shows the three marking lines on the panel. I also marked three lines on the temporary fence, but I needed only the middle one, which is aligned with the center of the bit. All I had to do was align the left-most line on the panel with the fence centerline, drill the counterbore, and repeat with the right-most line.




The resulting mortises were too small, and lacking the needed straight sides, so I used my narrowest chisel to cut out the rest. Norm Abram has nothing to fear from me, but the results were usable.




Here are the posts seated in their mortises. They won't rotate now.



With the posts (finally) installed, the back (and cabinet) was complete.