Tuesday, April 29, 2008

From Square to Round

(Posted by Scott B. Williams)

Today was my last day in the shop on this trip to Florida, and I completed what I came here to do, which was to build the Tiki 30 mast. This was also the most enjoyable work day of the trip, as I love the process of shaping a beautiful wooden spar from a rough glued up square box of wood. The chips were flying as I spent most of the day with a hand-held power planer, taking the square section first to 8 sides, then 16, and finally 32. The final rounding was done with a belt sander.

The first photo below shows the square section as it appeared when the clamps were removed first thing this morning. The plans show the amount of offset to mark the lines for the first cuts that take out the corners and produce an 8-sided section. I measured and marked these lines and cut the corners away roughly with a worm-drive Skilsaw first.

The final cutting down to the 8-sides lines was done with David's 6-inch Makita power planer.

Once the spar is cut to the octagonal section, two straight lines must be marked exactly 14mm from each remaining corner. This process took a bit of time. The corners were then removed with a smaller 3-inch Makita planer. Once this was done, there were 16 even sized sides. I removed the remaining corners from all these sides with the small planer, which resulted in 32 sides.

From this point, I was able to shape the mast to a round section using a 3 x 18" belt sander with a very aggressive 36-grit belt. This entire process took a full day, working alone, but now the mast is done except for finish sanding and fitting the top plate. It came out straight and is undoubtedly very substantial. While it is heavier than my Tiki 26 mast, it is not as heavy as I expected, consider the 25mm wall thickness.

The filleting and shaping of the tabernacle was also completed today and it is now ready for fiberglass sheathing.

Here is an aft view of the tabernacle structure, showing the hardwood mast step.

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