Friday, April 30, 2010
The above photo is showing how i cut the carbon cloth for the laminate. Instead of cutting the cloth dry to a rough fit or a close fit that frays every where and becomes messy. I laminated a large piece of cloth (measured beforehand) onto a plastic sheet (vacuum film in this case) once the cloth is wet out a second layer of plastic is smoothed out over the top. This gives a "Poor mans Pre-preg" where you can handle the cloth without it distorting or covering everything in resin. Then using a template and marker pen, the shape is traced and cut with scissors to give a neat non-fraying edge.
The backing plastic is then peeled off one side and placed into the mould carefully. With the backing plastic still on the carbon is stable and you can pull it up as many times as needed for a good fit.
Once it is placed in the plastic is peeled off and the rest of the laminate is applied like normal. I cut the carbon cloth on the +- 45 deg so give the board a greater stiffness from twisting. I also read recently that placing fibres on the 45 deg over Uni's helps to support them in compression so that they resist buckling better. This should help to give a stronger skin in compression. the rest of my rudder lay-up consisted of:
1x full cloth 200 gsm
1x full 300 gsm uni
4x tapered and progressively smaller layers of 300gsm uni.
1x cloth 200gsm on 45 patch at box exit.
The tapered layers resulted in the majority of the material on the max cord of the foil and around the box exit, (some tapered above this to the head of the board as well).
Both mould halves under vacuum. The bagging process was fairly standard, peel ply, perforated release film, bleeder, breather (shade cloth) then the bag. If you look closely at the above image you can see the bleed-out through the perforated release film.