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PGerringer

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As most of you know, my fillets turned out great. (IMHO) So, last night I lightly sanded everything, rounded out the fillets and primed the rocket. Well, the primer revealed tons of air holes in the fillets. So, how does one "fill up" the air holes? All I need is a seringe (sp?) with a small needle and glue/epoxy filling. Then I could inject the holes with stuff. Any ideas?
 
Phil,

There are almost as many ways to fill as there are models of rocket kits and each method works best on an individual basis/preference. Elmers All Purpose filler can be used successfully if it is diluted into a toothpaste consistancy. Another product that can be used if also diluted is Model Magic Filler. One of my favorites is using EverCoat Formula 27 All Purpose Filler, which can be found at some hardware stores and many automotive stores. I have used this filler for years on my R/C projects and it is great. It comes in a small can with a seperate small tube containing hardener. What I like most about it is, it set fairly fast and sands like a dream. Sanding does not build up in your paper and it comes off in a powder, extremely fine! I apply it with a credit card and fill the holes by actually pressing it in. The only disadvantage is when dry, even though it sands easily, it is hard as a rock and if you leave a thick spot, it takes some doing to cut it down. That's why you apply it as thin as can be. A good product.

Recently, I read where someone actually used thin CyA to coat the outside of their fillets; the CyA filled the holes and sanded into a smooth plastic coating (this is typical of thin CyA, a couple of applications to a balsa surface, some sanding, and you'ld swear the fin was made of plastic). This method is also heavily used in R/C building and works really well.

So, there are at least 4 choices. Since they are pin holes, I'd use the EverCoat (who, btw, is a big automotive paint mfgr) as it can easily fill even small pinholes. Simpler in design is the thin CyA and it appears to be a very fast method.

A tip when applying thin CyA to balsa and other surfaces. As I said, it is a great plasticiser if the proper application method is used. On a piece of balsa, I will apply thin CyA, then spread it with my finger, back and forth in a quick motion. When it begins to kick, aka get sticky, I stop spreading. I don't use kicker, but let it naturally dry, then, sand it with a block. I will apply another coat, spreading it again with my finger, then final sand once dried. It will litterally turn you wood into plastic! The trick is to keep you finger moving and smooth out any heavy areas. Once you are done, the tip of your forefinger will have this hard cap of CyA buildup on it, which easily pulls off in one piece.

Hope this helps,

Carl
 
Originally posted by PGerringer
As most of you know, my fillets turned out great. (IMHO) So, last night I lightly sanded everything, rounded out the fillets and primed the rocket. Well, the primer revealed tons of air holes in the fillets.

How big are the holes? If they are just pinholes, then the primer should fill them. If they are larger voids, then I think you have a problem with your epoxy or technique.
 
They are canyons. Well, that is an exaggeration. But they aren't pin holes. I'm sure it is my technique. This rocket is my first time with epoxy and I assume I will get better as time goes on. And I already think I know the problem: Either I poured too fast or I mixed too fast.
 
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