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locked Recommendations for me and questions

briddle@...
 

I have tried several different ways of filling in or hiding the
spirals on body tubes. I am not yet satisfied with the results. How
have others done it successfully?

Also, I am currently using Devcon epoxy. The 5 minute mixture is
fine and dries quuickly to a hard non sticky surface. However the 2
hour mixture literally has never completly dried to a non sticky
surface. It has always ended up tacky for the rest of my natural
life. What is considered the best brand of epoxy to use? And what
may I be doing wrong with the stronger mixture?

Fianlly....suggestions on how to BEST seal the fins before final
finishing? And best primer? I usually use Krylon line.


Thanks guys!

Bob
NAR 76749

Mike Leffler <mleffler@...>
 

Hi Bob,

For the grooves I generally use a lite-spakle such as Elmer's or DAP. I
also use the Krylon primers, although DupliColor has an automotive one that
is a little thicker. For the fins I use a thin foam roller and roll on a
coat or two of epoxy resin. Lastly, I have been buying the System Three
trial kit for epoxy, 12 oz plus all types of fillers, and fiberglass cloth
along with gloves, mixing cups, stir sticks, etc. the cost is $10.00
INCLUDING shipping and usually arrives in 3 - 5 days. Here is their link
and the list of kit contents. http://www.systemthree.com/index.html click on
trial kits.

Epoxy Trial Kit - $ 10.00

8 oz System Three Resin
4 oz Hardener #1
Silica Thickener
Wood Flour
Plastic Minifibers
Phenolic Microballoons
Squeegee
Brushes
Roller Cover
Graduated Cups
Stirring Sticks
Disposable Gloves
Fiberglass Cloth
The Epoxy Book
The Epoxy Catalog

Regards,

Mike Leffler
NAR 75646 L2

-----Original Message-----
From: briddle@... [mailto:briddle@...]
Sent: Tuesday, June 26, 2001 10:49 PM
To: MTMA@...
Subject: [MTMA] Recommendations for me and questions


I have tried several different ways of filling in or hiding the
spirals on body tubes. I am not yet satisfied with the results. How
have others done it successfully?

Also, I am currently using Devcon epoxy. The 5 minute mixture is
fine and dries quuickly to a hard non sticky surface. However the 2
hour mixture literally has never completly dried to a non sticky
surface. It has always ended up tacky for the rest of my natural
life. What is considered the best brand of epoxy to use? And what
may I be doing wrong with the stronger mixture?

Fianlly....suggestions on how to BEST seal the fins before final
finishing? And best primer? I usually use Krylon line.


Thanks guys!

Bob
NAR 76749


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kgholloway@...
 

Bob,

For filling in the spirals I first use a fingernail to compress both the
covered and uncovered spirals. What's the difference? Well when you first
look at the tube you'll see a spiral which is depressed below the surface
running the length of the tube. If you look closer you'll see a second
spiral that is covered by the surface layer of paper and which is the gap
between the second layer of paper. If you don't depress the surface paper
to conform to the bottom of this gap it results in a weak spot in the
finish that can come back to haunt you.

Once both spirals have been compressed I take Elmer's wood filler mixed
50/50 with water and paint it along the grooves. Then 48 hours later I
sand around the tube, not lengthwise, until the filler has been completely
removed from the normal surface. I then repeat this process until the
grooves are completely filled.

I also use the same 50/50 mix of Elmer's and water to fill the fins. I
first sand the fins with 100 grit paper to the shape I want. Then I apply
a coat of Elmer's, let it dry for 48 hours, and sand with 220 grit paper.
A second coat can be applied as soon as you wipe all of the sanding dust
off. I sand the second coat with 400 grit paper after 48 hours and, once
all of the sanding dust has been removed, the rocket is ready to be primed.

One item that is frequently overlooked is how to paint a plastic nosecone
correctly. If the paint doesn't adhere tightly to the nosecone it will
flake off on a hard landing. I first wash the nosecone with a paper towel
saturated with denatured alcohol to remove any release agent left over from
the molding process. I then sand the entire exposed surface of the
nosecone with 220 grit sand paper. Finally I once more wash the nosecone
with alcohol and let it dry for at least 24 hours before priming.

I prime with "KILZ" primer, using two coats applied 120 hours apart. I
sand the first coat of primer with 400 grit wet/dry paper used wet. The
second coat is sanded with 600 grit wet/dry again used wet. It's very
important to let the primer stand for 5 days before sanding otherwise
you'll take too much off.

Presently I finish the model with Krylon enamel paints in the spray can. I
spray a coat of paint and let it dry overnight. I apply a second coat the
next day and usually leave it at that. One warning with Krylon. If you
have to sand it to remove sags or drips it will have to sit at least 1 to 3
weeks. Otherwise it is too soft below the surface, probably due to
thinners that eventually evaporate. This long drying period is also
necessary if you're going to put decals over it. The thinners have a
tendency to loosen the decals over time if you put them on as soon as the
paint is dry to the touch.

In regards to adhesives I've heard that the best is West System's epoxy.
It's expensive, running about $25 per quart of resin and $12 per can for
the hardener. You'll need two cans of hardener, one type 205 (fast) and
one type 206 (slow) along with the special measuring pumps to fit the cans.
My next purchase of epoxy will be West's. At the present time I'm using
"Hanger 9" epoxy in both the 5 minute and 30 minute formulas for
construction and Zpoxy for a finishing resin for fiberglass cloth.

Hope the above is helpful to you.

Ken Holloway, NAR #78336, Level-1

Wolfram v.Kiparski <wolf@...>
 

Bob,

Like Ken, I also use Elmers Wood Filler and Kilz primer. I usually use three coats of
primer. Here are my other product recommendations:

I like Plasticote "Scratch Filling" Sandable Primer. They make several primers, but
only one high-solids variety. It is available at automotive supply stores where
mechanics go for parts (usually not the big chain stores). Kilz is more easily found.
If you alternate between Kilz (white) and Plasticote (grey), high and low spots
on your surface will become apparent when you start sanding the primer.

I also like to use Bondo Spot Putty - the reddish goop that comes in orange tubes.
It is easy (perhaps a bit stinky) to apply, and sands to a nice feathered edge.

kgholloway@... wrote:

In regards to adhesives I've heard that the best is West System's epoxy.
It's expensive, running about $25 per quart of resin and $12 per can for
the hardener. You'll need two cans of hardener, one type 205 (fast) and
one type 206 (slow) along with the special measuring pumps to fit the cans.
You don't really need both types of hardener to get started. I'm using the
105 resin with the 206 (slow) hardener right now. The epoxy takes over an
hour to gel. This might make for longer construction times, but I noticed that
because of the long working time, the epoxy soaks deeply into wood, cardboard,
and phenolic. This is a good thing! 5 minute epoxies cure so fast, there is
no time for it to soak in and deeply adhere to your substrate. West Systems
soaks right in. I tried some of the "hobby store" brands before settling on
West Systems. I still use Bob Smith epoxy (the generic stuff hobby stores like
to put their name on) because it is more convenient for mixing small amounts of
epoxy.

Hope this helps,

Wolf