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soarrich -> RE: (once again) plug question (2/22/2008 3:17:43 AM)
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quote:
ORIGINAL: dixielandsbigal
soarrich, my brain is not clicking right now. will you expand on your method you were explaining.
Explain: "just use it as a lost foam mold"
I think what your saying is use it as a "Male" mold, instead of using it as a plug. am i right? if so, would it be a lot harder to get a good finish if the "good side" is on the outide of the plug. Im new to all this, but i wanna give it a whirl. Thanks for the help.
Yes, but you can do it without as much sanding as crow thinks.
First you make the the male mold out of foam making it as smooth as you can using 100 grit sandpaper. After you have your shape cover it with packing tape, the thinner the better, keep wrinkles out by using lots of smaller pieces rather that just a few large pieces. I find it easiest now to lightly spray the form with 3M 77 spray glue now then lay on the fiberglass working out most wrinkles. Mist on a little more 3M 77 and then put another layer of glass. Now brush on epoxy, I use WEST 105/205, work it through the glass, when the epoxy is worked in the glass will be clear, any white spots aren't wetted out enough. Now use a roll of tissue paper and try to blot off the epoxy. The easiest way to do this is to roll the roll of paper over the epoxy in the direction that doesn't let the paper unwind, taking care to not lift the glass/epoxy mix. Once you have it so that it's wet but no drips, and in most places you see the weave of the cloth leave it to cure. After the cure, with 200 paper sand it for no more than one minute, you just want to get any little piece of glass that are standing up off. Now using the same 105/205 epoxy brush on a flow coat, you are just painting it on to fill the weave, let that cure. Now if you take a single edge razor blade and draw it backwards over the cowl you will quickly remove any excess resin. You should now have a cowl that after a few minutes of sanding with 200 grit paper can be primed, sanded, and painted.
I used to make whole sailplane fuses,(Weston Magics) this way. I did a cowl using this method, but over a balsa cowl that I had made, I'll see if I can find my pictures of it. It's covered with aluminum duct tape which have a few wrinkles in the tape not the glass.
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