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- After ensuring the fin can is cleaned, use a piece of paper, a ruler, and a sharpie to mark the centerlines on the fin can. Draw the line along the entire fin can to ensure visibility.
- Cover the leading edges with painters tape to prevent them from being covered in epoxy.
- While the lines and the leading edges are being drawnprepped, mix the first batch of epoxy. Start with 100g of resin and 18g of hardener, and then pour as necessary for the rest of the layup. Use a popsicle stick, and label the cup with its weight.
- Using the popsicle stick used for mixing, drizzle the epoxy from the cup onto the dry plies. Use enough epoxy that you can spread it around with your squeegee, and pass the epoxy to the next person to do the same.
- As you initially spread the epoxy, the ply might move around on its wax paper. Slowly spread until enough of the ply is wet that it stops moving. Make sure all the corners and edges are covered.
- Pro tip: lift the wax paper up and check the underside to identify light areas you may have missed
- Once you're sure you've covered the ply, start to pull epoxy out. There's a lot of nuance to this. Basically, press down with your squeegee and follow the direction of the ply until you near the edge. Then lighten up on the pressure and pull off the ply.
- You should have a line of epoxy on your squeegee. Run your squeegee along the side of a spit cut to remove it.
- Lightening up the pressure near the edges helps prevent warping.
- Once you can no longer see any large shiny pools on your ply, move it up to the next section of the table (yellow as shown in the table diagram above), and grab another dry ply. Repeat steps 3-6.
- Once a ply in the yellow section has sat for a few minutes, use a squeegee to continue pulling epoxy out and dumping it into a spit cup. Letting it sit allows excess to pool.
- Once a ply has been pulled enough, move it to the ready station. It's important to always have a ply ready to ensure that the assembly line process is moving as fast as possible so that we can quickly get to the bagging phase.
- At the ready section, use a sharpie to mark the centerlines onto the plies wax paper. This helps the person laying up the plies with proper placement.
- Take the ply from the ready station, and line it up on the fin can using the wax paper. The trailing edges may not always line up because the plies are tapered. The two things to check:
- Are the leading edges lined up
- Are the center lines lined up
- Slowly press the wet ply onto the fin can, starting from the middle of the wax paper and moving outwards. The ply should reach the tip chord of the fin if they're sized properly.
- Once firmly attached, pull the wax paper off. Then rotate the fin can and lay down the next ply. Repeat steps 9-11.
- Trim the edges as needed. The carbon fiber shouldn't go over the leading edges.
- If there's excess on the trailing edge, leave it. This is helpful for post-processing.
- Once you reach ply 6, have someone switch off of pulling epoxy and start prepping the vacuum bags.
- For a room temperature cure, use the green stretchy one.
- With one sheet of the pre-cut bagging material, lay down the vacuum tape as shown in the second square. You're basically trying to go ~1/3 of the way along the length on the top and bottom, and along the entire length on one of the sides.
- Slowly apply the tape to the bag, ensuring that there are no wrinkles under the tape. Wrinkle = air path = leak
- Take the next piece of bagging material (the lighter green) and lay it on top of the previous sheet. Again, slowly seal the sheet to the tape to prevent leaks.
- Fold the new sheet over, and repeat the step b-d.
- Stop once you've sealed off three corners. It should kind of look like the diamond thing on the right of the diagram. The corners are for the fins. The last corner that hasn't been taped yet will be used to dress the fin can and slide the vacuum connector in. Leave the bag off to the side until all the plies are placed.
- Cut some extra pieces of tape off to the side for the last corner and for the phenolic tube.
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- You better have everything kitted at this point. Take the painters tape off the leading edges and do any final trimming.
- Clean off the edges of the fin can (the exposed 1" of phenolic) with acetone and shop towels.
- The vacuum tape does not like epoxy, so be sure to clean it off well.
- If you have leftover vacuum tape from the overwrap cure, it might be easier to take a razor and scrape off the tape than to clean it.
- Lay down the peel ply (nylon, blue). Make sure to leave the 1 inch on the side for vacuum tape.
- Cut off excess
- Make sure every part of the carbon fiber is covered in peel ply
- Tape the layers of peel ply to each other with flash tape
- Lay down the release film (red, perforated). Make sure to leave the 1 inch on the side for vacuum tape.
- Cut off excess
- Make sure every part of the carbon fiber is covered in the release film
- Tape the layers of release film to each other with flash tape
- Lay down 2 layers of breather per side. Make sure to leave the 1 inch on the side for vacuum tape.
- Cut off excess
- More breather is better than less.
- Lay down one ring of vacuum tape on either end of the phenolic tube. Press down really head to ensure that it sticks to the tube. Keep the white paper on until you're ready for the bag to attach.
- Put the bag on over the fins.
- Slowly remove the white backing of the vacuum tape on the ends of the tube, and slowly attach the bagging material to it. Have extra piece of vacuum tape handy to fill in gaps.
- Slide the vacuum connector in.
- Put it on a bed of extra breather cloth to prevent wrinkles, and try to sick it towards the bottom of the fin can.
- Seal the bag with vacuum tape.
- Find the connector, cut an X through the bag into the hole, and attach the vacuum hose to it.
- Pull vacuum. Check for leaks. Your goal is -26 mm Hg.
- Leave the vacuum pump on for 24 hours at least.
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