fin fillets
 

I am new to this hobby and I just finished building the estes crossbow sst, didn't fly to well but I learned a bit about construction techniques. but I also came up with a couple questions:
would krazy glue do for CA?
what epoxies do I need, 6min, 5min, 30min etc? any other supplies for working with this adhesive?
and how do make fin fillets? tack the fin on with CA, then apply epoxy and smooth it out?
any other methods? perhaps easier and quicker and just as purdy?
also, if I am to use epoxy for the fins, would epoxy putty from home depot work?

Krazy glue is a brand of mass marketed CA.

You don't need any epoxy for model rockets unless it's a special application. You also don't need CA unless it's for a special application. Plain old white or yellow glue is all you need for 98% of model rocket construction.

Most of us use the double gluing method with white or yellow glue to apply balsa fins, but a few do use CA to tack the fins on before finishing up with white/yellow glue. Do a quick search on "double glue joint" and you will find several posts explaining it.

We normally use white or yellow glue for fillets unless we are building larger high power rockets. For model rockets, all you do is run a bead of white/yellow glue at the fin/body tube joint and smooth it out with your finger. For high power rockets you can do the same thing with epoxy, but use latex gloves.

Epoxy for model rockets is overkill. It's heavy compared to white/yellow glue, more of a mess, more expensive, etc. I never have glue joint failures when using white or yellow glue on regular body tubes and balsa fins. The body tubes rip or the fins break and the glue joint hangs together.

looking at your 2929 post count :eek: I will trust your advice

And I really love sanding. :eek: :rolleyes:

I use epoxy as the final fillet on any model that I am concerned about finish on. Since it does not shrink it leaves nice, smooth fillets with no bubbles. Overkill for strength yes, overkill on looks no.

A post count only indicates that someone posts a lot.

Now, if you saw some of the staging photo's tbzep has posted, then you would have a good measure that he knows what he's doing.

You can get a very pretty fillet using white or yellow glue. Noticeable shrinkage usually comes from big fillets. Big fillets aren't needed, but if you want them, just make a small one, then come back later and do it again. They come out nice and slick as long as you don't try to get big ones with one pass. I seldom get bubbles, but on the occasion that I do, I just pop them with the tip of my X-acto knife or a T-pin and let the glue flow into it.

True... I just never have to come back and do them again with epoxy... I guess I'm just lazy that way :)

I like to use epoxy with any rocket that launches with a motor bigger than a C

Quite true, and may I add that if you subject a rocket made with white or yellow glue to heat for an extended period, such as in a hot car, with the rockets lying on their sides, the fin attachments to the body tube tend to soften up, and they will move. Also, if you store them that way (on their sides), they will move (flatten).
To prove this, shoot off a BT-20 sized rocket; when you recover it, wiggle the fins. They will move.
A little epoxy for fillets makes for a fabulous finish that is very strong and much less influenced by heat. Use 5-min for attachment (just a smear is all that's needed) and use 30-min for the fillets. Alcohol cleans everything up nicely.
The weight penalty is quite small, and since I really could not care less about 'competition' where weight savings are a premium, I build using this technique 90% of the time, from low power to Mid power. My rockets last a long time. No brittleness with time as with the white or aliphatic glues, either.
Now, micromax rockets are a lot easier to build using white or yellow glue. I hate the bubbles, though.