Originally Posted by RuneW
Yes, yes, I can hear you guys
But it must
involve a little bit of luck to get the end caps that
tight, doesn't it? I myself cannot imagine how you could actually measure that precise. Well, a few test runs with the router would help, I guess...
If you haven't cut circles with a router (go with a plunge model) on a circle jig, you're going to like it. You can use a model that isn't a plunge, but if you're buying one, you're first router should be a plunge.
Like Will said, go with a setting that is too large, and sneak up on it in (hopefully) small increments until you get to the point where you're about 2mm too big. Put a chamfer or round-over on the edge that goes into the tube first.
Once I had all my caps glued and cut (yes I glued my cap layers together while square, then cut circles), I thined down some polyurethane with mineral spirits and sealed the MDF. That keeps the edges perfect, even after lots of insertions/removals (assuming you're going with a dry fit).
I would guess the waxed tubes are better for this because the cardboard is then sealed on the inside. I'm new to speaker building, but generally in woodworking, when you have one side that is sealed, you want to go ahead and seal the other as well. Since we're dealing with mostly enclosed volumes here, this isn't so important though.
The 3M spray adhesive stuck great to the wax surface when I put the batting in. My ports are also wax coated cardboard tube and enamel paint just sprayed down the tube on a warm day worked perfect also.