Scratchbuilding a B&O RR stick lighter: Pt. II 2.
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1. This is the beginning of the “egg crate” assembly that forms the core of the barge hull. The three longitudinal stringers have been shaped to the sheer line and the half-lap joints cut into them. Two of the transverse bulkheads have been fitted. The top edge of No. 6 has been filed to shape (the deck camber) while No. 7 has been marked where the tops of the stringers are, but has not yet been filed to shape. Note that each bulkhead will wind up
3.
being a different height, thus the need to carefully number them. 2. This photo shows the completed egg crate construction. The half-lap joints should slide together easily, but not sloppily. A lit- tle play in the fit will ease the final assembly of the whole core. When all these pieces are glued together, an extremely strong as- sembly results. Note that the ends of the stringers still need to be cut back to provide the vertical face of the ends.
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3. Here the various components of the hull’s core assembly have finally been glued together, and, with tape and plenty of weights, has been left to dry. Note that the mast has been “stepped” temporarily to make sure that it is correctly posi- tioned. Doing this now assures a nice tight fit when the mast is permanently mounted in the hull. The weights are old lead type purchased some 40 years ago at a junk/second hand store in Manhattan. It turned out to be a good investment. 4. The shaded area on the upper edges of the center stringer and bulkheads 8
that the mast may be installed. Having the bulkhead there against the mast will provide maximum strength to the mast. Clamp the three stringers together and set your table saw so that the blade extends ³₈″ above the table. Cut a slot ¹₈″ wide in the tops of the stringers at each of the nine locations previously marked. The spacing is not critical. What is criti- cal is that the cuts be square and line up exactly across all three stringers. The sheer line can now be cut in the upper edge of the stringers. This may very well be the most difficult part of building the
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and 9 mark the recessed area that will receive the deckhouse. Also in the photo is the deckhouse, which is basically finished on the inside. The final work (trim) on the outside will be com- pleted later, after the deck planking has been laid. This will en- able the trim to be fit to the deck itself, giving a nice tight joint. You can also see how the author added some plywood to brace the mast. The center stringer was cut away in front of bulkhead number 7 and two scraps of ply were glued in place. When the glue was dry, the hole to step the mast was carefully drilled.
barge, as these are concave cuts and the plywood is more difficult to cut than sheet basswood. The safest way I can think of to do it is to score lightly and re- peatedly through the outer ply until you have scored the inner ply. When both sides are done you should be able to snap the center ply, then finish the top edge smooth with sandpaper and a block of wood. When all three are done, clamp them together and sand the ends and bottom until the ends and bottom edges are identical. The center stringer should
be a scale 6″ higher than the two outer ones throughout their length. Set them aside for now.
Now you need to cut sufficient strips of plywood to make the nine transverse bulkheads. Rip the strips a scale 5′-3″ high and cut them a scale 32′-0″ long. Use a red felt tip marker to mark one long edge of each piece; this will be the bottom of each bulkhead. Measure from the bottom edge of the stringers to the bottom of the notches you previously cut. This should be about ³₈″ or so, de- pending on your particular model. Set
JANUARY 2013
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