Fins

[carson]

I'm sure this has been answered 50 times but what do you do to fins when building a rocket.
Wood glue and paper?
Epoxy and paper?
Just epoxy?
I thinned alittle wood glue, brushed it on the fins, added card stock paper and set a heavy book on top.
As I put the book on top, I noticed some bad warping.
Not sure if it will flatten when it dries.
How do you all do it?

 

[Stewart32]

I spread CA over the surface of the sheet stock, let dry, then sand. I do this 3 to 4 times as needed for a strong smooth finish.

 

[Zippy]

For LPR I use pretty much the wood glue, paper technique only I use typing paper instead of card stock. It also depends if the fins are Balsa or Basswood. I leave the paper off of Basswood becouse it's allready pretty strong. I then skim coat with Bondo Spot Putty becouse I like a smooth finish.
For HPR if they are plywood fins I either glass them or just coat with epoxy then skim with Bondo putty for the finish. If they are G10 I only work the joints with glass/epoxy/bondo since (pun intended) G10 is allready as smooth as glass.

 

[DynaSoar]

Originally posted by Carson
I'm sure this has been answered 50 times but what do you do to fins when building a rocket.
Wood glue and paper?
Epoxy and paper?
Just epoxy?
I thinned alittle wood glue, brushed it on the fins, added card stock paper and set a heavy book on top.
As I put the book on top, I noticed some bad warping.
Not sure if it will flatten when it dries.
How do you all do it?

Assuming you mean wood, for balsa I seal with Deft lacquer sanding sealer, sand, seal, sand, primer, paint with white satin finish, and finally spray color. Basswood only needs one coat of sealer, as does birch plywood. Satin finish fills what the deler doesn't.

I've covered both wood and styrene fins with adhesive vinyl -- one step start to finish.

 

[jflis]

for model rocketry I simply use white glue to attach. Sometimes I use CA to tack it in place. I make fillets with white glue. I don't go too overboard because they are easier to repair that way.

Case in point, I built a Richter Recker and epoxied the fins on and built up fillets with epoxy. good and strong. One day I bumped the rocket hard enough to tear off a fin. That destroyed the entire fin can area and it had to be rebuilt. My most recent Richter Recker just uses white glue. Plenty strong enough for flying and when I bumped it on the way home from NSL, the fin snapped cleanly off and the model was repaired and ready for flight in a few minutes.

for sealing I've been experimenting with Elmers Fill-n-Finish and KLINZ Primer also. Not enough information yet to draw a conclusion, but I *do* like the Fill-n-Finish

jim

 

[lalligood]

I'll cast a vote in favor of Elmer's Fill 'n' Finish. It does need to be diluted with water so that it's the consistency of something along the lines of ketchup. You just want to spread enough to cover the surface/fill in the grain. Put it on too thick & it'll take forever to sand smooth once it dries! One application, sand it down & it's ready for paint

OTOH, I recently used Kilz primer for the first time. I know that there are a number of folks here on TRF that swear by the stuff so I figured it was worth a shot to try. I knew it was a "high build" primer, but what came out of the can really blew me away! Me personally, I learned that I do NOT like to sand. Kilz was overkill. Worked a little too well if you ask me... I never would've known that I didn't care for the stuff (both Kilz & sanding! haha) until I tried it.

Diff'rent strokes for diff'rent folks.

 

[BlueNinja]

I usually don't seal the fins on my rockets. When I do, I water down some FNF and apply it with my finger.

 

[DJ Delorie]

On my most recent kit, I use Elmer's Fill-n-finish followed by Bondo sandable primer. The FnF was easy to use, I probably should have done two or three coats of that though, had a few grain lines left. The Bondo is sweet - dries in five minutes, sandable or paintable in only 30. Between the two you can go from raw balsa to a gloss paint coat in one day.