Ok, I was trying to learn something the hard way, that is figure it out. In
particular, how do you properly use fiberglass to reinforce/fillet a fin
Wha I have achieved so far:
1) On overpowering headache from the smell of the resin - Ok proper
ventilation will help that.
2) A gooey sticky mess. Here is where I could use some pointers.
Is it better to mix the resin, apply it to the airframe, and press the dry
composite into the root or use a paper mache technique where you dip the
composite in the resin and lay it down wet?
If there is any reference material available, I'd appreciate it if anyone
who can point me in the right direction.
As Tim indicated, it sounds like you're using the wrong resins. A
respirator is a better idea than ventilation, anyway.
I've done both, but for reinforcing fillets, I prefer to run the strip
of cloth through the resin then use gloved fingers to squeegee all the
excess off, and lay it down in place. Nitrile gloves are great for
this, as they allow you to get "hands on".
If it's a joint down inside a body tube, a dowel can be used to position
the strip. Lay the strip lengthwise down the end of the dowel, and
allow it to fold in half. Then roll the strip off of the dowel and into
the fillet. Takes some practice, but it's doable and works well.
On both of these points, it sounds like you used polyester instead of epoxy.
Polyester stinks, has a short shelf life, and is a PITA to work with.
Usually just a few drops of catalyst to a large amount of resin. If that's
what you got, trash it now.
Go with something like System 3, West, Raka, etc instead. In fact, buy or
download the System 3 book for answers to most of your questions.
Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD"
>>> To reply, remove the TRABoD!
I think you have two separate questions here; filleting and reinforcing.
ROL InfoCentral has some tips on glassing:
A Google search with "rocket fins fiberglass" should turn up a few
For reinforcing, I use thin epoxy (or alcohol thinned epoxy) on well
sanded tubes with the fins mounted. I cut out a piece of cloth to go
from fin tip, across the body tube, and to the tip of the adjacent fin
with the weave crossing the fin roots in an "X" pattern. Allow some
overlap on all fin edges. I wet the surfaces with a thin layer of epoxy,
lay the cloth from one fin tip to the other, and fill-in dry spots or
dab off wet spots. If you use thin (long setup time) epoxy, let it soak
in a few minutes before applying the cloth. After the epoxy dries, I
trim and sand the overlap. I use foam brushes for glassing. Work your
way from one point to another in laying the cloth, don't lay the entire
piece down at once. "Tugging" or pulling the cloth once it is down may
pull it up and away from the fin/tube joints. You want intimate contact
between the glass and rocket.
I don't have trouble with epoxy fillets cause I don't try to make them
perfect. ;) I use twenty or sixty minute epoxy, dab it along the joint
with a stick and let it "mold itself" into a fillet shape. I use
FillnFinish after the epoxy dries to make up for my chad application.
I accidentally stepped on a LMR cluster bird with TTW glassed fins
(don't ask). The only parts to survive were the fins.
If you're trying to reinforce a plywood fin mounted on a Kraft paper
body tube, forget the epoxy. Use Titebond and triangular balsa to
reinforce your fins at the root. It's easier, lighter AND stronger.
NAR 71503 Level II
God Bless our peacekeepers
I'm not sure what I am using (and will look). It is some stuff I got at a
auto parts store. My only previous experince was in helping a buddy glass a
hood scoop to a car, and that was 25 years ago. Came in a 1 qt can and the
ration is 1oz of resin to 12 drops of catalyst.
Thanks for all the info so far.
That's polyester resin.
Epoxy, as noted, has much less odor (compared to the
strong distinctive scent of polyester resin) and is
generally easier to work with. Just be sure to measure
accurately and mix very thoroughly for best results.
David Weinshenker wrote in
And different epoxies have different mix ratios,like 2:1 resin/hardener for
RAKA and System 3,and West is,IIRC,5:1 or 2:1 depending on which hardener
System Three has a really fabulous TRIAL KIT (for 10 BUCKS PPD!!)that gives
you a generous sample of epoxy and hardener,PLUS different fillers like
wood flour,silica,microballoons,and plastic fiber,and the VERY informative
Epoxy Book,which every epoxy user should read.
You can't go wrong in buying this trial kit.
Disclaimer;I'm not an employee of S3,nor financially or otherwise connected
They're also insanely expensive, and hard to find locally. I'd much rather use
polyester resin that I can buy at any hardware store for $20 a gallon, than
spend several times that much plus shipping (and waiting for it to arrive.)
Epoxy resin is about twice as strong as polyester resin.
It also costs about twice as much.
Polyester is not so bad if you are vacuum bagging. Heck I might even
recommend vacuum bagging even if its not really doing anything but keeping
the smell down.
I get mine at the boat store down the street, but I live on the coast.
I work for a fiberglass gelcoat company and went and had a long talk with
one of the lab technicians. I was told that the absolute best solution for
what we are doing is to use "vinylester resin". The tech claims it has the
topmost strength yet not having the characterics of being brittle like
polyester resin would have. I've so far glassed two rockets with it and have
had one hard landing on concrete with nothing more than a little paint chip.
Excellent stuff !! I use a 1 part DDM9 catalyst to 100 part vinylester resin
for best results. Sorry but i haven't done any research on the web as to the
location of this vinylester resin seeing how what I get is available at work
but unfortunately not to outside sources. Any direct fiberglass distributor
would have the knowledge as to getting the stuff i'm sure.
I've use TAP 314 "marine grade" resin from the local Tap Plastics -
I think it's pretty similar to West or System 3.
(These days I tend to prefer Aeropoxy laminating resin from Shadow Aero
unless I'm in a hurry - it's lower in viscosity and wets out _really_
nicely, but it is a bit more expensive and fairly slow-curing at room temp.)
Hmmm... TAP has that (as well as several flavors of polyester and epoxy) -
I might have to get some just to try. (Always good to explore options).
I wonder if it shares polyester's short shelf life - I've had the experience
of getting a can of PE resin, using some of it, and coming back a couple
of months later to find the remainder gelled or hardened in the can.