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Building Tips and technical articles. => Building techniques => Topic started by: Paul Wood on June 27, 2011, 12:43:10 PM
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Last one
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If you have one of those kitchen vacum sealers you could do vacum bagging and use CF instead of FG, although vacum bagging would help with FG as well. They work great for small parts. You just have to be careful that the appliance does not suck up any resin or it gums up the works.
Pssst... Don't let the wife catch you, especially if you bought it for her as a dual purpose gift, if you catch my meaning...
http://www.costco.com/Browse/Product.aspx?Prodid=11300615
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Paul,
You did not say what process you used. Vacuum formed? Glass and dissolve the foam?
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Tom,
It's not vacuum formed. Just lay up the first layer with heavy (5 oz) glass cut into strips to allow forming in tight areas. Then three or four layers of light (3/4 oz) glass. I use finish epoxy, but 30 minute thinned very lightly with alcohol works well also. I do not dissolve the foam as some do. It's just toooo messy! I gouge the foam out using various knives, chisels, rasps, fingernails, etc. Then I use a rag wetted with gasoline to clean the foam that remains in the weave of the cloth. The foam is really easy to dig out rather than dissolve. For surfacing, micro balloons or Bondo work equally well. It's really an easy process, but the foam block must be accurate. The fiberglass will exactly follow the contours of the foam.
Paul
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Nice job Paul, couple of questions.
Do you have to sand the mold undersize to allow for thickness of the finished part, if so any tricks for doing that accurately ?
Do you coat the foam mold with anything to help with release from the fiberglass layup ?
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Nice job Paul, couple of questions.
Do you have to sand the mold undersize to allow for thickness of the finished part, if so any tricks for doing that accurately ?
Do you coat the foam mold with anything to help with release from the fiberglass layup ?
Allan,
You do not have to use any release agent. Just dig out the foam. Of course the mold is only a one time use item, hence the term "lost foam method" you may read about. My technique for "undersizing" is to pull a block sander with 220 grit across the face of the foam two times. You only need to remove about .03 in. and that's not much foam. You can also sand the finished part quite aggressively to correct any area that is slightly oversized. The tolerances are so small that it really is not an issue. The differences can actually be corrected to either piece with a little additional primer build up.
Paul