Bolero Project | Monday, March 17, 2008

I spent the entire day working on the cabin trunk/coaming assemblies, completing the various tasks required before their final installation.

My first task was to cut the port openings.  I needed precise, clean openings since the inside would be frameless, so I chose to use a router and template to make the cuts.  So to begin, I made the template for the port openings on a piece of 3/4" plywood.  I traced the inside edge of a port frame, cut the shape carefully with a jigsaw, and then fine-tuned it and cleaned it up using a drum sander in the drill press. 

When I was happy with the shape, I used the template to make a test cut on some scrap wood.  I used a plunge router with a 1/2" straight bit and guide collar, and made the cut in three passes.


Satisfied with the template and the process, I prepared to make the four cuts in the actual cabin trunk sides.  For each of the cuts, I followed the same process.  The layout lines for the ports' locations were still in place, and it was simple enough to align the template over the marks on the board in each location.  Still, I must have checked the location several times over, since this was not a place for haste.

For the scrap test cut, I had secured the template to the wood with some double-sided tape, but I wasn't confident enough in the tape's ability to hold the template securely to use it on the actual mahogany pieces, though that had been my initial plan.  Instead, I secured the template with screws:  the template protruded far enough above the top edge of the mahogany so that I could drive two screws through the top edge of the template and into a pine backing board that I placed beneath the cut area to prevent tearout on the bottom of the mahogany and to protect the bench from the cut; at the bottom side of the template, I drove two screws directly into the mahogany without worry, since the screw holes were in the area that'd be hidden from view below deck level when the cabin trunk was installed (i.e. on the bearing surface where the mahogany would bolt to the sides of the deck opening). 

After a few more checks of the location, I made the cuts, which fortunately went flawlessly in all four instances.


Next, I carefully positioned each individual port frame over its respective opening (each frame was just slightly different in overall shape thanks to the casting and polishing process, so I labeled each with its proper location) and used a self-centering bit to drill pilot holes for the mounting screws.

I milled a 1/4" wide rabbet just over 1/4" deep around the edges of the openings on the exterior side; this rabbet was where the 1/4" Lexan or glass inserts could eventually sit.  I didn't want to make the rabbet much wider overall, since I wanted to ensure plenty of wood around the screw holes for the frames, but I considered making the rabbets wider in between the holes; eventually I decided that the initial rabbet was sufficient and would provide plenty of bearing and sealing surface for the eventual port material, whether Lexan or glass, given the very small area of the openings.


I now faced a critical aesthetic decision:  how to treat the interior edge of the port openings.  Since there'd be no frames on the insides of the openings, I wanted the transition from the flat surface to the recessed opening to be attractive and provide an appropriate appearance.  I spent some time considering the router profile bits I had on hand, and made several test cuts on scrap wood to consider various bits.  Eventually, I settled on a small beading bit set to less than its full depth, which provided a clean, interesting profile without being overly fussy.

However, before routing the profile on the insides of the port openings, I sanded the pieces as required through 220 grit, since I didn't want to sand away any of the delicate profile once it'd been milled.  I also routed rounded edges on the top edges of the coaming portions of the assemblies, and on the inside bottom edge of the entire piece.  Once everything was smoothly sanded, I routed the profile on the port openings and did some touch-up sanding as required.

My final milling step was to mill a shallow rabbet at the leading edge of each cabin trunk piece, roughly 3/4" (just barely under) from the forward edge, and following the line of the exposed portion of the edge.  These rabbets would accept the forward side of the cabin trunk later.

Finally, I predrilled holes and countersinks for a series of 1/4" bronze fasteners that I'd use to bolt the boards in place; the countersinks would eventually receive bungs to hide the bolt heads.  Then, I cleaned up the boards and applied a sealer coat of varnish to both sides of each.


Total Time on This Job Today:  7.5 hours

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