This is a part 2, to the instructable I wrote about creating a radio control sailboat on Autodesk Inventor. This will go through the steps of putting it together.
We will be using a carbon fiber kite rod for the mast and booms. We will use a piece of steel rod for the keel bulb. I drew a balsa keel to be filled with lead shot on the drawing but then read somewhere about a kit that used a chunk of steel rod and thought that was a much easier approach. That's what we will use.
Step 1: Deck, Hatches and Servo Mount
I needed to design a servo mount, the deck and some access hatches. The rudder linkage will have a circular hatch that's screwed in place. The main hatch over the servos, receiver and battery will be a small sliding hatch. Both hatches and the deck will be 1/16" plywood. The servo hatch will be 1/8" plywood. Time to get more time with the laser cutter.
Step 2: Laser Cut the Parts Out
I laser cut 3 sheets worth of parts. The parts consist of a 24"x6' sheet of balsa, a 24"x12" sheet of 1/8" aircraft plywood and a 24"x6" sheet of 3/16" sheet of ply.
I used the following settings on the laser cutter which was a 60 watt Epilog.
Balsa 1/8" 35 speed, 40 power, 500 frequency.
Plywood 1/8" 35 speed, 85 power, 500 frequency.
Plywood 3/16" 10 speed, 85 power, 500 frequency, * 3 passes.
I think 3/16" aircraft ply is really at the limit for this laser cutter. You might be able to get 1/4" out of it but I'm sure that's the thickest this cutter will possibly do.
Step 3: Glue the Keel Box Together
Remove the longitudinal former and keel box sides from the part sheets. Glue them together with CA. Be careful to align then top edges so that the formers will align into the slots okay later on. I used Zap brand CA glue to put everything together here.
Step 4: Gather Up the Parts for the Hull
Remove all the hull parts from the part sheets. Some care is needed not to split the balsa parts about their centerlines in the process. If you do split a part, you can glue them back together so it's no big deal.
Step 5: Assemble the Jig Saw (laser Cutter) Puzzle
All the parts for the hull can now be assembled into position. All the parts had interlocking slots in them. Put everything together on a flat surface and press all the bulkheads into the deck. Get everything aligned as good as possible.
Step 6: Glue It All Together
Put drops of CA glue along the edge of intersecting parts. Work your way around the boat and add glue at all the joints. I like to push down on the longitudinal former while doing this to keep everything flat against the building board. A little accelerator spray will make the glue dry instantly and make this job go very quickly. Once it's all glued together you can pick up the hull.
Step 7: Add the Balsa Stick Stringers
Next, add 2 balsa stringers down the corners of the bulkheads. These are made from 1/8" x 1/4" balsa stick. They are just for the purpose of giving the sheeting for the sides and bottom something to glue to. The fit isn't terribly important. You will need to soak them in water for a while to soften them up to the point they will bend around the front. The easiest way to glue these on is to start at the rear, glue the transom and rearmost bulkhead and make sure they are set and work your way forward. When you get to the front, you can look down and trim the front to the right length to get it to fit up into the notch at the first former.
Step 8: Add Rudder Tube Doublers
Glue on the the 2 rudder tube doublers. These are just so that you have enough of a block of wood to drill a hole for the rudder tube in. The 3/16" ply would be not quite thick enough on it's own.
Step 9: Sheet the Bottom of the Hull
I put sheeting on the bottom surfaces of the hull. I used 1//16" Balsa. I used 3 inch wide sheet for this. I glued the wood down the centerline of the boat first. Then flipped it over and applied CA to the bulkheads and stringers on the edge, one of 2 bulkheads at a time. There isn't that much curvature to the hull bottom so it goes pretty easily. After gluing the sheet on I trimmed around the edge with an exacto knife and then sanded the rest of the extra away. The I repeated for the other side. For side 2, you may need to trim a little bit from the centerline edge to get it to fit up against the side you already have on. Then repeat the gluing, trimming and sanding process. After this, trim away the excess around the keel hole also. I just used an exacto knife and cut against the plywood for a guide.
Step 10: Sheet the 2 Sides.
Next apply the sheeting to the 2 sides. For this I used 2 sheets of 1/16"x4" x 36 inch sheeting. You could buy a sheet of 48" and cut it in half. I find it easiest to start by gluing the sheeting to the boat between the 2 bulkheads around the mast step. From here it's very easy to glue the sheet to the rear half of the boat. The curves are relatively gentle and the sheet will take the bends with no problem even if you bought relatively stiff balsa. For the front half of the boat you will have to wet the wood to get it to bend around to the bow. I did this by going into the bathroom and holding the boat over the sink and rubbing water onto the outer surface of the sheet until it felt soft enough to take the bend. For gluing this on I glued the bow and front bulkhead using a bit of CA and accelerator and then went and glued the rest of the bulkheads and edges. Before doing the other side you need to at least trim and sand the bow because it will be overlapping where the other side goes. Once you do that, repeat for the other side. I like to let the balsa completely dry before doing any sanding or trimming.
Step 11: Clean It Up and Fiberlgass
Trim the sheeting and sand it smooth. I went over the whole hull with a 150 grit sanding sponge. This is just so smooth up some of the roughness of the balsa. Once that is done it's time to start fiberglassing the hull. I used 1.5oz glass cloth. This is commonly available at most hobby stores and one package of it will give you enough for several boats. I cut a piece out big enough to cover the bottom of the boat. I will do this in 4 pieces. One for the entire bottom, one of each side and one for the transom. I used Z-Poxy laminating epoxy resin which is fairly thin. I have had a couple of bottles of it that have lasted me a few years of building.
I find it easiest to CA glue a few spots of the fiberglass down to hull first. This keeps the glass from sliding around too much while applying the resin. I put the resin on by spilling some onto the hull and then working it into the glass cloth. It's much easier to do this then to put resin down on the wood surface and lay the glass cloth on top of it and work it down that way. You will tend to use way too much resin. I use rubber gloves to rub the epoxy in and spread it out. Then let it rest over night before moving onto the next piece.
Step 12: Finish Glassing the Other Sides
I put glass on the rest of the sides and the transom. I trimmed everything off and sanded a bit to smooth it out. It will need one more coat of resin still.
Step 13: Waterproof the Inside
To make the boat last a bit longer, it's a good idea to coat the wood on the inside of the boat with something to make it water resistant. I used West System resin thinned with Denatured Alcohol. I thinned it about 30% or so. The epoxy paints on pretty easily and soaks into the wood good enough to seal it.