salvatoreone wrote: ↑Wed Jan 06, 2021 4:11 am
I watched many videos about moulding and it seems relatively easy and with beautiful surface finish right off the mould but they all just make parts that are either simple panels or more complex parts that have two surfaces parallel to each other. I don't get how you make it for a wing which has asymmetrical top/bottom surface :/
I could have maybe taken some more photos to show it better, but perhaps the screenshots of the model below helps.
The top and bottom half of the mould is shown below. Top half in green, bottom half in blue. The trailing edge of the wing is used for the split line. When the two halves of the mould are fitted together, the void left on the inside is the exact shape of the wing.
Then to find out the shape of the layers to cut out of the carbon fibre / fibre glass: In this case I wetted out about 1x1 m of carbon fibre at a time (each layer is about 0.2 mm thick) and I stacked them 3 layers thick before cutting, so 0.6 mm thickness in total. So To find out what shape to cut these into, to stack in the mould, I just chop the model of the wing into 0.6 mm thick layers. See screenshot below.
I place these 0.6 mm shapes onto a A1 drawing sheet and get it printed at a officeworks. (See a copy of the drawing below). So after I wet out the 0.6 mm carbon fibre / firbeglass, I put one of these drawing sheets down on it, and then cut out the shape. That cutout shape then just gets placed in the mould (Remember to make sure the mould is smoothly sanded and give it a good 10 applications of mould release wax to make life easy). So 14 of these shapes get placed in the top mould and 6 shapes in the bottom mould. (I Place the largest shapes on the outside and smaller and smaller on the inside, that way you see a full continuous layer of carbon fibre / fibreglass on the top and bottom when you open the mould). The mould then gets closed and bolted and clamped very tightly, squeezing out any extra epoxy. I also make up a thickish mixture of epoxy and microballoons and place it in the middle of the wing, to make sure all the space is filled and excess is squashed out, that is the white stuff seen around the wing in the below photo, the extra mix that was squeezed out.
Trim/sand the extra off around the wing. Give the wing a good light sanding to make sure it is all smooth. Wait a few days (5 days recommended for the epoxy to reach good strength) and go kiting!!
I just need to decide what kind of wing I want to make!
I have little motivation at the moment since it's cold, get's dark early, and 15cm ice on the fjord by house.