Making balsa fins stronger and filler

Making balsa fins stronger and filler

Post by Randy Mille » Tue, 17 Dec 2002 05:04:48



I am curious about what everyone likes to do for making balsa fins stronger
and what is a good filler.
I have tried brushing on CA but it's a pain to sand the fins after it dries.
I have also tried Weld Bond mixed with water but that didn't work out too
well. For filling balsa I have tried Min wax sanding sealer and I have also
tried Micro-Fill and Elmer's wood filler and gluing on printer paper. Oh and
I hate sanding.

Thanks
Radar

 
 
 

Making balsa fins stronger and filler

Post by Stefan E. Jone » Tue, 17 Dec 2002 05:13:13


Quote:

> I am curious about what everyone likes to do for making balsa fins stronger
> and what is a good filler.
> I have tried brushing on CA but it's a pain to sand the fins after it dries.

CA is a good hardener, but it isn't a filler. And as you note, it
doesn't sand worth a damn.

Quote:
> I have also tried Weld Bond mixed with water but that didn't work out too
> well. For filling balsa I have tried Min wax sanding sealer and I have also
> tried Micro-Fill and Elmer's wood filler and gluing on printer paper.

Elmer's wood filler, slightly thinned, is wonderful stuff. The trick is
to wait a few DAYS before sanding.

Gluing on paper is a good tactic, but you'll STILL be filling and
sanding! Paper is porous, and in any case the edges and seams need to be
filled and sanded.

Quote:
> Oh and
> I hate sanding.

GET OVER IT! #B^)

Seriously, lots of sanding, with the proper material, will GREATLY
improve the look of your models.

Buy some mylar-backed sanding material, and get a few sanding blocks
(used with strips of regular sandpaper). These make things a lot easier.

Stefan

 
 
 

Making balsa fins stronger and filler

Post by Brett Buc » Tue, 17 Dec 2002 05:26:27


Quote:

> I am curious about what everyone likes to do for making balsa fins stronger
> and what is a good filler.
> I have tried brushing on CA but it's a pain to sand the fins after it dries.
> I have also tried Weld Bond mixed with water but that didn't work out too
> well. For filling balsa I have tried Min wax sanding sealer and I have also
> tried Micro-Fill and Elmer's wood filler and gluing on printer paper. Oh and
> I hate sanding.

   Both problem can be solved using 90-year old techniques. Tissue and dope!

    Brett

 
 
 

Making balsa fins stronger and filler

Post by Tim Van Millig » Tue, 17 Dec 2002 05:49:02


Quote:

> I am curious about what everyone likes to do for making balsa fins stronger
> and what is a good filler.
> I have tried brushing on CA but it's a pain to sand the fins after it dries.
> I have also tried Weld Bond mixed with water but that didn't work out too
> well. For filling balsa I have tried Min wax sanding sealer and I have also
> tried Micro-Fill and Elmer's wood filler and gluing on printer paper. Oh and
> I hate sanding.

> Thanks
> Radar

Getting a good finish comes down to "technique," not the materials you
use. The best way to learn a technique is by watching someone else do it
properly. I highly recommend the video book: "Building Skill Level 1
Model Rockets." It will show you the right techniques to use to make a
fantastic rocket. You can find more information at:

http://www.apogeerockets.com/skill_level_1_video.asp

Good Luck,

Tim Van Milligan
Apogee Components, Inc.
1130 Elkton Dr., Suite A
Colorado Springs, CO 80907-3514
USA

Tel: 719-535-9335
fax: 719-534-9050
web site: http://www.ApogeeRockets.com

P.S. Check out our FREE weekly model rocketry e-zine. It contains
articles to help you get more enjoyment out of model rockets. The older
articles are indexed at:
http://www.apogeerockets.com/education/newsletter_archive.asp

Sign up to receive new articles by email by sending any message to:

NOTE: We respect your privacy, and your email address will never be sold
or redistributed.

 
 
 

Making balsa fins stronger and filler

Post by shockwaverider » Tue, 17 Dec 2002 05:54:11


radar:
seriously consider replacing balsa with plywood....as far as filling, consider either min-wax polyacrylic or epoxy finishing
resin....squeeze the fins between two heavy flat metal plates and wax paper....

shockie B)

Quote:

> I am curious about what everyone likes to do for making balsa fins stronger
> and what is a good filler.
> I have tried brushing on CA but it's a pain to sand the fins after it dries.
> I have also tried Weld Bond mixed with water but that didn't work out too
> well. For filling balsa I have tried Min wax sanding sealer and I have also
> tried Micro-Fill and Elmer's wood filler and gluing on printer paper. Oh and
> I hate sanding.

> Thanks
> Radar

 
 
 

Making balsa fins stronger and filler

Post by Gary Deave » Tue, 17 Dec 2002 08:42:29


Carbon and Kevlar tissue used with lamenating epoxy
can drasticaly improve balsa. I believe ACP sells it.
Gary Deaver

Quote:
> radar:
> seriously consider replacing balsa with plywood....as far as filling,

consider either min-wax polyacrylic or epoxy finishing
Quote:
> resin....squeeze the fins between two heavy flat metal plates and wax
paper....

> shockie B)




Quote:
> > I am curious about what everyone likes to do for making balsa fins
stronger
> > and what is a good filler.
> > I have tried brushing on CA but it's a pain to sand the fins after it
dries.
> > I have also tried Weld Bond mixed with water but that didn't work out
too
> > well. For filling balsa I have tried Min wax sanding sealer and I have
also
> > tried Micro-Fill and Elmer's wood filler and gluing on printer paper. Oh
and
> > I hate sanding.

> > Thanks
> > Radar

 
 
 

Making balsa fins stronger and filler

Post by Dan Winin » Tue, 17 Dec 2002 10:10:59


One method not mentioned so far is to use eithet 1/2 or 3/4 oz
fiberglass and finishing epoxy. It both strengthens and fills at the
same time, the key is to use only a small amount of resin, and to
either vacum bag it, or to s***off the excess epoxy.

Tissue and dope works too, but you get better strengh with fiberglass.

I have also seen contact paper used.

On Sun, 15 Dec 2002 20:04:48 GMT, "Randy Miller"

Quote:

>I am curious about what everyone likes to do for making balsa fins stronger
>and what is a good filler.
>I have tried brushing on CA but it's a pain to sand the fins after it dries.
>I have also tried Weld Bond mixed with water but that didn't work out too
>well. For filling balsa I have tried Min wax sanding sealer and I have also
>tried Micro-Fill and Elmer's wood filler and gluing on printer paper. Oh and
>I hate sanding.

>Thanks
>Radar

 
 
 

Making balsa fins stronger and filler

Post by J.A. Miche » Tue, 17 Dec 2002 11:12:50


I have laminated balsa fins with carpenter's glue and card stock with
excellent results.  You will have to sand and finish the edges.  I had a
rocket crash with these type of fins once.  The surface mounted fin failed
the body tube, but the fin did not break.

J.A. Michel


Quote:
> I am curious about what everyone likes to do for making balsa fins
stronger
> and what is a good filler.
> I have tried brushing on CA but it's a pain to sand the fins after it
dries.
> I have also tried Weld Bond mixed with water but that didn't work out too
> well. For filling balsa I have tried Min wax sanding sealer and I have
also
> tried Micro-Fill and Elmer's wood filler and gluing on printer paper. Oh
and
> I hate sanding.

> Thanks
> Radar

 
 
 

Making balsa fins stronger and filler

Post by shro » Tue, 17 Dec 2002 11:17:03


Basswood is nice too.

Shrox
----------------------------------------------

Quote:

>radar:
>seriously consider replacing balsa with plywood....as far as filling, consider either min-wax polyacrylic or epoxy finishing
>resin....squeeze the fins between two heavy flat metal plates and wax paper....

>shockie B)


>>I am curious about what everyone likes to do for making balsa fins stronger
>>and what is a good filler.
>>I have tried brushing on CA but it's a pain to sand the fins after it dries.
>>I have also tried Weld Bond mixed with water but that didn't work out too
>>well. For filling balsa I have tried Min wax sanding sealer and I have also
>>tried Micro-Fill and Elmer's wood filler and gluing on printer paper. Oh and
>>I hate sanding.

>>Thanks
>>Radar

 
 
 

Making balsa fins stronger and filler

Post by BJames » Tue, 17 Dec 2002 11:52:19


I vote for gluing on a layer of typing paper on each surface.  Then I spray on
a couple of coats of Krylon sandable primer, sand lightly, and paint.  This is
quick and dirty, but works pretty well.

If you need stronger fins than this then you should be using plywood.  If you
want a better finish than the primer over paper, then you will need to spend a
lot more time on it.

 
 
 

Making balsa fins stronger and filler

Post by GCGassaw » Tue, 17 Dec 2002 16:52:59


Quote:

>>>>CA is a good hardener, but it isn't a filler. And as you note, it doesn't

sand worth a damn.<<<<

I would not suggest that CA is a good filler in an overall sense, but it does
have its uses for specific situations

And actually CA sands incredibly well. I have used it in spots where the balsa
surface not only needed to be very smooth, but hard so it could take somewhat
more abuse than normal. Like a shuttle orbiter nose made out of balsa.

Applying the CA can be tricky, takes some development of a knack for doing it.
The worst thing to use is fresh thin CA, it wants to "set off" into hard blobs
before it can be smoothed out. Thick CA is better. OLD CA is better still,
normally CA you do not want to use for building, but it's good to keep for this
kind of thing.

Unfortunately, applying CA over a relatively large area creates a lot of fumes
that can be overwhelming. So best of all is to use foam-friendly "odor-free"
CA, the thick type.

I apply the CA it with my fingers. Yeah, "eeew", but I've gotten used to CA
getting on my fingers and peeling it off later. For those not inclined to do
that, then try wrapping some plastic film over a finger, or using something
that CA does not bond to (this would be the kind of thing one might want to use
***gloves for, but the CA would stick to the latex).

After the CA is applied and has cured solid, when you sand it, start off with
something like 240 to 320 grit paper to get the high points off, so it is a
pretty uniform surface. Then go to 400 grit, and finish off with 600 grit.
Wet-sand when using the 400 grit and finer paper.

- George Gassaway

 
 
 

Making balsa fins stronger and filler

Post by Bob Kapl » Wed, 18 Dec 2002 03:15:47



Quote:
> I am curious about what everyone likes to do for making balsa fins stronger
> and what is a good filler.

Fillers and sealers add little to no strength. The only things that really
strengthen balsa are laminates that cover the surface. Several ofthem have
been mentioned already, from jap tissue to fiberglass to carbon fiber or
kevlar matte. One that's been skipped is Monokote or other iron on covering.

        Bob Kaplow      NAR # 18L       TRA # "Impeach the TRA BoD"
                >>> To reply, remove the TRABoD! <<<
Kaplow Klips & Baffle:      http://www.pleimling.org/le/Phantom4000.pdf
    www.encompasserve.org/~kaplow_r/    www.nira-rocketry.org    www.nar.org

        26-October, 2001: A day that will live in infamy
        Support Freedom: http://www.indefenseoffreedom.org/

        Men never do evil so completely and cheerfully as when they do it
        with religious conviction. --  Blaise Pascal

 
 
 

Making balsa fins stronger and filler

Post by Bob Kapl » Wed, 18 Dec 2002 03:16:22



Quote:

>> I am curious about what everyone likes to do for making balsa fins stronger
>> and what is a good filler.
>> I have tried brushing on CA but it's a pain to sand the fins after it dries.

> CA is a good hardener, but it isn't a filler. And as you note, it
> doesn't sand worth a damn.

And does little to strengthen the balsa.

        Bob Kaplow      NAR # 18L       TRA # "Impeach the TRA BoD"
                >>> To reply, remove the TRABoD! <<<
Kaplow Klips & Baffle:      http://www.pleimling.org/le/Phantom4000.pdf
    www.encompasserve.org/~kaplow_r/    www.nira-rocketry.org    www.nar.org

        26-October, 2001: A day that will live in infamy
        Support Freedom: http://www.indefenseoffreedom.org/

        Men never do evil so completely and cheerfully as when they do it
        with religious conviction. --  Blaise Pascal

 
 
 

Making balsa fins stronger and filler

Post by Bob Kapl » Wed, 18 Dec 2002 03:17:51


Quote:

> Basswood is nice too.

Basswood has the same unidimentional grain weakness as balsa. I'd rather use
model aircraft ply instead of basswood for most applications.

        Bob Kaplow      NAR # 18L       TRA # "Impeach the TRA BoD"
                >>> To reply, remove the TRABoD! <<<
Kaplow Klips & Baffle:      http://www.pleimling.org/le/Phantom4000.pdf
    www.encompasserve.org/~kaplow_r/    www.nira-rocketry.org    www.nar.org

        26-October, 2001: A day that will live in infamy
        Support Freedom: http://www.indefenseoffreedom.org/

        Men never do evil so completely and cheerfully as when they do it
        with religious conviction. --  Blaise Pascal

 
 
 

Making balsa fins stronger and filler

Post by Brett Buc » Wed, 18 Dec 2002 05:06:00


Quote:


> > I am curious about what everyone likes to do for making balsa fins stronger
> > and what is a good filler.

> Fillers and sealers add little to no strength. The only things that really
> strengthen balsa are laminates that cover the surface. Several ofthem have
> been mentioned already, from jap tissue to fiberglass to carbon fiber or
> kevlar matte. One that's been skipped is Monokote or other iron on covering.

    Monokote is OK, but it doesn't add nearly as much stiffness as the
others. Same is true about most synthetic coverings, like polyspan
(polyester tissue) or Micafilm.

     Jap tissue and graphite mat +dope seem to be about the best
stiffness/weight ratio. Graphite and epoxy, besides being much more
difficult and demanding to apply (pretty much has to be vacuum-bagged or
otherwise pressed), is  heavier per unit stiffness.

   People seem to be unimpressed with dope as a surfacing adhesive, but
it's plenty strong enough on balsa.

    Micafilm can't be torn, so it's great for creating a handy disposal
bag for model airplanes after crashed. The structure is pulverized, but
the covering stays intact; just take it to the nearest trash can and
drop it in.

    Brett