To create the curved top eight pieces of horseshoe shaped MDF are laminated together. The first step in making the horseshoes is to create a template. The template is cut from a piece of MDF that was ripped to width for the top. The band saw is used to cut the template to approximate size and the edges are sanded to shape with a spindle sander. Using the template and a router with a pattern makers bit the top curve was cut on sixteen pieces. (Image 2) The interior curve of the top does not need to be perfect as it his hidden within the enclosure, so this is simply cut on the band saw. (Image 3)

Due to the fact that 3/4" MDF is not truly 3/4" thick one of the horseshoe pieces has to be reduced in thickness. Otherwise, the stack up of all the pieces for the top would not equal the desired width of the sides. Two of the sixteen pieces are sanded with a surface sander to reduce the thickness, then the pieces are ready to go. (Image 4) Alternatively, the sides could be made wider to match the stack up of the top pieces.

The horseshoes are glued together with polyurethane Gorilla Glue (Image 5) and the ends are trimmed flush after the glue tried. (Image 6) The top pieces should not be sanded now, as the front and back pieces of the enclosure will add to the laminated top. Sanding is done once the enclosure is fully assembled to ensure a smooth and consistent half dome top.

With the curve cut on the top of the front and back pieces I was ready to cut openings for the drivers in the front. I laid out the front panel of the TriTrix on a piece of MDF, cut the openings with a jigsaw and sanded to the line with the oscillating spindle sander. (Image 7) Then, I clamped this template to the front pieces and used the router to cut the openings. (Image 8) To recess the drivers into the front panel, I used a rabbeting bit and the router table to cut rabbets on the openings.

For access to the inside of the cabinet I chose to cut a rectangular opening in the bottom of the back panel. The cover for this opening would contain the port, crossover and terminal cups. A rabbet was cut around the edge of the panel so the panel would integrate into the opening in the back of the enclosure. (Images 9& 10) The port opening was cut with a jigsaw and smoothed with the spindle sander. The exterior edge of this opening was given a large round over to minimize the chance of port noise while a rabbet was cut on the inside edge to receive the piece of 2" PVC pipe that would be used for the port. (Image 11)

Rather than using tee nuts to install the drivers, I ordered threaded inserts at the local Fastenal. (Image 12) These are installed by drilling a hole and then threading in the insert with an allen wrench. I installed the inserts on the inside of the panels by first drilling holes with the drill press. Then I sawed off an allen key, chucked it in the drill press and turned the spindle by hand to thread the inserts into the MDF. This ensured the inserts were installed squarely.

Realizing that it was going to be difficult to align all the pieces once the edges were coated with glue, I cut slots to receive biscuits on the front, back, sides, middle brace, and bottom. (Images 13 & 14) After a test fit of all pieces (Image 15) I cut pieces of egg crate foam to fit behind the drivers in the upper portion of the enclosures. This would later be installed through the driver openings. Gorilla Glue polyurethane adhesive was applied to all edges and the enclosure was clamped together (Image 16).

Once the glue dried the clamps were removed and the glue squeeze out was scraped away. A 1/2" round over was routed on the front of the enclosure and a 1/8" round over on the rear of the enclosure.