I trimmed the top and bottom edges even on the bandsaw, using the bending form to establish a reference surface.
After the motor housing was laminated into its curved shape, it needed trimming on four sides. This took some cogitation, to develop a reference surface against which to square the cuts. Here was my thinking.
The most important thing was that the housing should appear to sit square on the motor, with its front (curved) surface vertical. That surface was hard to use as a reference, but the inside of the curve (which was parallel to the outside) was easy. All I had to do was put the housing back on the bending form and press it against the curved nose. Then, if I spaced the form away from the fence and pushed it through the bandsaw blade, I’d cut an edge that would be square to the curved nose, as in the photo.
Trimming the ends of the curved housing was easy, again using the bending form.
Once one edge was done, I just flipped the form over and ran the trimmed edge against the fence to trim the opposite edge. The form supported the “U” shape, which otherwise would have chattered up and down as it grabbed and released the blade.
The next step was to trim the open ends of the “U”, square to the edges and even with each other. Here again, the bending form made things easy. I used a square to mark a line across the width of the form at the right distance from the curved end, and set the bandsaw fence so the blade would cut at the line. Then I pressed the square end of the form against the fence and cut first one side, then the other. They came out square and even. (Note—this worked because my form was wide enough to stay square to the fence. If it was narrow, I’d have used a sled or miter gauge to keep it square during the cut.)
The resaw blade was still on the bandsaw, and I resawed a 1/4″ thick slice of the same Honduran Mahogany used for the sides of the motor housing and glued it onto the top edge of the “U”. I glued it with the grain running along the sides of the “U” because it will expand and contract with changes in humidity, slightly flexing the walls of the “U”. If I’d glued it across the “U”, sooner or later its seasonal movement would have broken the glue bond.
Once the glue dried, I trimmed it within 1/8″ of the housing sides with the bandsaw, then used a flush-trim router bit in my router table to bring its edges flush. In this operation the bit runs against the grain for half the cut, potentially yielding a torn out surface. What I did was to use a normal cut (moving the piece against the rotation of the bit) for the right side of the cut, then use a climb cut (moving the piece with the bit’s rotation) for the left side. This way, the cut was always supported by fibers beneath it. It took several light passes, but the final cut was just about perfect, only requiring light scraping with a card scraper to produce clean, flush edges.
I sanded all surfaces to #180, then finished them with the same gel polyurethane varnish I used on the rest of the cabinet.
Next, the installation and lessons of the project.
