Thursday, July 17, 2014

Core Sound 15 Centerboard Construction

Below is a video of the process of cutting and gluing up the quarter-sawn strips of wood that make up the centerboard. The finished blank for the centerboard is very stable because we "end for end" every other strip in the board which cancels out the bending or twisting tendencies of any individual strip. The strips are oriented as close to quarter-sawn as possible to reduce the effects of expansion and contraction of the wood.

Ideally this process starts with a straight plain-sawn board with little twist. The boards I used were not as plain sawn as they could have been and so I ended up with some strips that resemble more rift-sawn cuts. One could be more picky with their strips and weed out the rift-sawn ones.

After the blank was glued up it was put on the CNC machine to be shaped. The creation of the part files takes about twice or even 3 times as long as the cutting itself. The entire process took about 6 hours to draft the centerboard in 3 dimensions and create the cutting files. That includes the surfacing and hole drilling and outline cutting. Each of these processes involves a different set of menu options in the software and each produces a separate file. It is not as easy as throwing in your 3d model and out pops a centerboard. Each file has to be referenced correctly to the origin so that all the cutting operations happen in the right spot in relation to all the others. Otherwise the two halves of the board might not match up!

Here is a video of the processes that went into cutting out the centerboard. The obvious advantage to this method is that another centerboard can now be created using these files in a fraction of the time. And all in all, the final product is more accurate that one could hand shape given 6 hours with any hand operated tool.

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