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gerbs4me

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I have made a NC out of foam for my 4" L1/L2 project rocket, now this is the white styrofoam thats rough, I coated it with glue so I would be able to paint it, but its still not smooth, what I mean is when I run my hand over the NC it feels wavy, its probably from the glue, I appled witha brush, I have put about 5 or 6 coats of it on the NC. What can I do to make it smooth?
 

cls

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Gerbs, I don't think you can ever get that coarse styrofoam to be smooth. hopefully someone here has a better idea but here's my take:

if the NC has a simple shape (like a Black Brandt) you should wrap some fiberglass around it. if the NC has a compound curved shape (Like a Fat Boy or a "regular" ogive NC) then it will be difficult to get the glass to lay flat.

epoxy will stick, but both polyester and vinylester resins will eat the styrofoam.

hmmm, worst case: want to coat the NC with epoxy and run the orbital sander over it?
 

Manwithbeers

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Just like Cliff Said. Epoxy with lots of lightweight fairing filler in it. Spread it like frosting. let it cure then sand to shape. Belt sander prefered but a file would do well too. See http://oberon.ark.com/~lkvend/rocket.html for pictures from a 4" nose cone constructed this way.

Enjoy
Layne Rossi
CAR S767 L2
 

cls

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I'd use the orbital sander, or maybe even one of those triangle finishing sanders.

the belt sander I save for big stuff like cleaning all the rocket glue & paint off the kitchen table!!
 

sandman

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gerbs,

Try the epoxy coating and filler, then, carefully center it in some kind of lathe thing...here is what I mean.

Make a mandrel mount that can turn (by hand is all you need) and mount a section of body tube long enough to nsert your freshly epoxied(and cured) nose cone.

Get a helper...this will take a second person...to sllllooooowly turn the nose cone (be sure it is centered and not wobbling)!

As it is turned...start your belt sander and carefully, gently bring it up to the nose cone as the cone is turning.

Let it ever so gently "kiss" the high spots. Use a light touch...NO pressure against the cone! I use a portable light to "backlight" the cone so I can see the high spots as they "kiss.

This can usually work for a cone that is "out of round" too.

sandman
 
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