First test tube is out of the mould. Last night around 2130 hours I began cutting and wetting out glass. Three layers of glass and three additional layers where the beam is to go. The evenings goal was to learn how to do this properly, and I certainly reached that goal!
1: Have a table for wetting out long enough for the whole piece of cloth you are working on. If not, the cloth will be hard to wet out properly and you will have to handle the cloth some, which it dont like.
2: This is a two person job. One mixing epoxy and one applying it. 3 persons would be even better.
2: Put all the layers of cloth in position on the table before putting them into the mould. Otherwise it is hard to align them properly.
3: The bag should not be too large, just a bit larger than the mould. If it is too large you get wrinkles!
After running the pressure up to 2 bar last night, the bag decided to start leaking. Somehow it managed to rupture close to the air-inlet. It was not a large hole, just 2 cm, but enough to create trouble. To try and save the situation I ran the compressor continously, but I did not take the chance on letting it run without rest for the whole night. The compressor managed to hold the pressure at 2 bar, but I suspect that the result would have been even better without the leak.
As it is, the tube is not perfect. At some places there are dents.. It looks like these dents are located where the bag have been twisted a bit? A smaller bag and no leaks should help. As the picture below shows, there is a dent where the bag have "folded" due to excessive materials in the bag.
Here is a pic of the bag inflated, resting on the bottom part of the mould. It is quite a bit larger than the mould, which I think is part of the problem.
Anyway, before committing carbon fibers, I will want to make another test run with glass.
The good news is that the finish of the beam is very nice and the method obviously works. Even with 6 layers of glass at one beam end the pressure made the laminate conform very well to the mould and no air-bubbles, gaps or anything. Overlap was very hard to see as well, so the pressure must have been immense. Considering -1bar is a perfect vacuum, 3 bars should be more than enough to consolidate the laminate for our beams.
Here is a pic of Omar with our beam mould. Looks quite dangerous! Considering that the mould holds 3 bar of pressure when the pic was taken, Omar was a bit skitterish :-)