fill & finishing fins.............

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Rob Fisher

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My most least favorite part of model rocket assembly. Does anyone have a method that is quick & yields great results? I currently use sanding sealer but it seems to require many coats & tons of sanding & the results aren't always the best. I would like my balsa fins to have a smooth metal like finish!
 
I mix water with the filler to a mayonase-like consistency than brush it on thick, once dry I sand with a sanding block if possible. never takes more than one coat.
 
Thanks, I'll give it a try.-by filler I guess you mean wood filler? That sanding sealer stuff smells so strong it practically gets you high, -being winter & having to work in the house and all!
 
Oh, man-this is a godsend! I have 4 rockets waiting on fin finishing & have been dreading using that sanding sealer stuff. No fumes, water based for easy brush cleaning & one good coat does it! BTW I'm using elmers carpenters wood filler, stainable interior white.
 
Originally posted by Rob Fisher
BTW I'm using elmers carpenters wood filler, stainable interior white.

I've never tried the Elmer's carpenter's wood filler but I've read here that it is VERY comparable to Elmer's Fill 'n' Finish. I've been using F'n'F for quite some time & have always gotten very good results. Only time I've ever had to use more than one coat was for large balsa nose cones. Great stuff & easy to use! (Like was mentioned earlier, I dilute it to a smooth, creamy consistency too.)
 
I use fill n finish, sand smooth and then coat with a water based sanding sealer from WalMart craft section. No odor and the brushes wash off with water. It works very well and after the fill n finish one coat of sealer leaves it like plastic.
 
I also find FnF a wonderful improvement in fin finishing.

The only problem I've ever had is with very dry (20 years old) 1/16th inch plywood. They warped badly after using FnF. Sure made for a corkscrew flight. I guess my mistake was using too much water to thin it--it could be easily brushed on.

Has anyone else had a problem with plywood warping?

It never seems to bother thicker plywood or non-ply basswood or non-ply balsa.

Just to be safe now, I don't use as much water. That mayo-like consistency mentioned by stymye is about what I create. Then I rub it on with a finger. It's a bit more messy and takes more time to sand off, but it works great.

In any case, FnF is a dramatic improvement over sander sealer. Seems to work well filling any voids in epoxy fillets also so the fin-fillet interface is entirely smooth.
 
Fill-N-Finish works well. You can dilute it, as stated here, or just rub it in "dry". If you dilute it, do both side of a fin at the same time to reduce warping. I bought some Fill-N-Finish a few days ago. The UPC code was 2600000836 (preceded by a small 0 and followed by a small 5). They had stuff with the new name too, but the UPC code was the same. Confirm the right stuff by verifying the code.

(OK, you retentives out there, I know the C in UPC stands for Code,so "UPC Code" is redundant.) ;)

Other methods include papering the fins or using really thick filling primers. I've used the Fill-N-Finish and paper methods with good success, but I've not tried the thick primers.
 
Instead of sanding sealer, I use Minwax Polycrylic. It's waterbased, doesn't stink, and the brushes clean up with soap and water.

I used to use multiple coats until the grain was filled and it left a hard surface which seems to resist dents more than unfilled fins but it takes too many coats to completely fill the grain.

Now, I give fins and nose cones a coat of Polcrylic and let it dry. I then use Elmer's Carpenters wood filler. After sanding, I give the fins a final coat of Polycrylic.

It probably is much like the water based sanding sealer that rbeckey uses. It leaves a hard smooth plastic-like finish.
 
OK, I don’t wish to hijack this thread but this is a similar problem that has been holding me up on the construction of a Guillows shuttle I’m converting for flight. I ditched the plastic film covering and used 1/32” balsa sheeting to produce smoother lines over the stringers on the wings and body. Now I’m looking for a method to fill the grain without adding a ton of weight in filler. One method I’m looking into is using silkspan but then it will need filled as well. I’m looking for something that will except paint well once it is on. Thanks.

steve
 
Fill n Finish can add on some weight on a big span like that. I would suggest Balsa Dope it does not add as much weight and sand smooth as glass. Boy does it stink it is pungent stuff and the smell is the main reason that I do not use if often.

You can also use the Dope and silk or tissue paper to make the wing coverings. Check out the RC guys groups as they have lots of information on wing surfacing.

Scott
 
Originally posted by Rob Fisher
My most least favorite part of model rocket assembly. Does anyone have a method that is quick & yields great results? I currently use sanding sealer but it seems to require many coats & tons of sanding & the results aren't always the best. I would like my balsa fins to have a smooth metal like finish!

I use Deft spray lacquer sanding sealer. One coat (that is, two think coats a few minutes apart). Dries in 15 minutes. Sand with 400 grit. Dust it off and coat it again. Sand it with 600. If there's any hint of grain left, a third coat and 600 grit takes care of it, but then so does satin finish paint, which I use as base coat, or appliance epoxy which needs no base coat OR primer.

I use it on the body tubes too, because it makes them stronger and helps fill spirals.
 
i have the same issues with redoing some old rockets from my childhood.

then i stumbled upon a neat little mistake

if u rub a thin layer of wood glue onto the wood evenly and let it dry u can get a nice solid finish when painting over it. makes it strong too

that or u can try wet sanding, but its more of thoughs long hours we all hate so much
 
Originally posted by Const Star
if u rub a thin layer of wood glue onto the wood evenly and let it dry u can get a nice solid finish when painting over it.

Be careful with this approach. You can use water-based glues, you can even thin them a bit before applying, but you need to sand them (lightly). It would be even more helpful to spray a light primer coat like Kilz before painting.

If the glue 'primer' is the only thing under your paint, you will often get a paint failure called crazing. The paint will crack and shrink, and may even peel off. Your finish coats may not do this until some time later, but many paints are not very compatible with a wood-glue base.
 
had that happen to me on some previous things ive painted in the past, and had it crackle for some reason or another. pisses me off, cause most of the time i have no idea why it does it.
 
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