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Old Sep 15, 2007, 07:57 PM
Doug McLaren
Guest
n/a Posts
Repair with fiberglass?

I've bot a Bird of Time ARF that was crashed that I want to repair.

The nose was smashed up nicely, and there's some cracks in the
fuselage. Pictures at

http://mclarenhome.com/~dougmc/RC/bot-repair/

Now, as far as repairs go, this is a simple one. The nose is pretty
bad off, but I could fix it with strapping tape if I wanted to do a
half-assed job of it. And the fuse is still reasonably strong where
it cracked a little, but I'd like to beef it up a little, as the crack
will move if pressure is put on it.

Taping up the crack isn't so great, as it seems something with
compressional strength -- which packing tape does not have. But
fiberglass would do it nicely.

So, I was thinking of using fiberglass, putting a few strips over the
parts that need repairing. Any thoughts?

I've got some of this stuff --

http://www2.towerhobbies.com/cgi-bin...&I=LXL491&P=ML

is that what I want? I've used regular building epoxy with this in
the past, and it seemed to work OK, but I'm reading more stuff online
that says to use something else ...

In the past, when I cut the fiberglass cloth, the ends frayed badly
and it sort of made a mess. Any way around that?

As I understand it, I should sand a small part around where my repair
will go so the epoxy will stick better, get it really clean, then put
everything where I want it (and make sure it doesn't move later), and
put a few strips of fiberglass saturated with epoxy on it, and let it
all set. Once it's all done, sand it smooth and paint if I want.

Anything else?

--
Doug McLaren, dougmc@frenzied.us
The beatings will continue until morale improves!
Old Sep 15, 2007, 09:24 PM
Martin X. Moleski, SJ
Guest
n/a Posts
Re: Repair with fiberglass?

On 15 Sep 2007 23:57:07 GMT, "Doug McLaren" <dougmc+usenet-20070915@frenzied.us> wrote in <1189900070.8584@frenzied.us>:

>I've bot a Bird of Time ARF that was crashed that I want to repair.
>
>The nose was smashed up nicely, and there's some cracks in the
>fuselage. Pictures at
>
> http://mclarenhome.com/~dougmc/RC/bot-repair/


Nice pix.

>Now, as far as repairs go, this is a simple one. The nose is pretty
>bad off, but I could fix it with strapping tape if I wanted to do a
>half-assed job of it. And the fuse is still reasonably strong where
>it cracked a little, but I'd like to beef it up a little, as the crack
>will move if pressure is put on it.


>Taping up the crack isn't so great, as it seems something with
>compressional strength -- which packing tape does not have. But
>fiberglass would do it nicely.


>So, I was thinking of using fiberglass, putting a few strips over the
>parts that need repairing. Any thoughts?


BTDT. Pix here:

http://picasaweb.google.com/martin.m..._models_rc_air

I used the heaviest fiberglass I have. Two layers of
3/4 oz. should be fine.

I think I used medium CA on the exposed fiberglass first,
thinking it would soak in better than epoxy. YMMV.

I probably also roughed up the gel coat to try to get
a better bond for the epoxy/fiberglass band-aid.

Scratch that--I put the band-aid on with medium CA, too.
I didn't want to mess around with epoxy, I guess.

The other places where the gel coat got broken off,
I used CA & microballoons (first repair--my crash)
and epoxy and microballoons (a friend's crash).

All of that stuff looks horrible both in the picture
and in Real Life (tm), but it's under the wing and
doesn't show in the air.

>I've got some of this stuff --


> http://www2.towerhobbies.com/cgi-bin...&I=LXL491&P=ML


>is that what I want? I've used regular building epoxy with this in
>the past, and it seemed to work OK, but I'm reading more stuff online
>that says to use something else ...


I've used epoxy and CA with fiberglass. Both seem
to work well.

>In the past, when I cut the fiberglass cloth, the ends frayed badly
>and it sort of made a mess. Any way around that?


Some folks spray the cloth with ... uh ... 3M Super 77 contact
cement. I haven't tried that.

If you use a sharp knife (#11, new blade), a straightedge
that you can press down right where you're making the
cut (a piece of aluminum works OK), cut on the bias
(a 45-degree angle away from the way the weave, and use
a soft cutting surface (I have one of those green
self-healing pads), you can minimize the fraying.

>As I understand it, I should sand a small part around where my repair
>will go so the epoxy will stick better, get it really clean, then put
>everything where I want it (and make sure it doesn't move later), and
>put a few strips of fiberglass saturated with epoxy on it, and let it
>all set. Once it's all done, sand it smooth and paint if I want.


Painting is optional. I believe in Ugly Insurance myself
(as you can clearly see in the pix).

We broke it. We fixed it. It still flies. If
anyone complains about how bad the plane looks, I'm
willing to let them take it home and improve it all
they want.

Marty
--
Big-8 newsgroups: humanities.*, misc.*, news.*, rec.*, sci.*, soc.*, talk.*
See http://www.big-8.org for info on how to add or remove newsgroups.
Old Sep 16, 2007, 04:26 AM
Ed Cregger
Guest
n/a Posts
Re: Repair with fiberglass?

Doug McLaren wrote:
> I've bot a Bird of Time ARF that was crashed that I want to repair.
>
> The nose was smashed up nicely, and there's some cracks in the
> fuselage. Pictures at
>
> http://mclarenhome.com/~dougmc/RC/bot-repair/
>
> Now, as far as repairs go, this is a simple one. The nose is pretty
> bad off, but I could fix it with strapping tape if I wanted to do a
> half-assed job of it. And the fuse is still reasonably strong where
> it cracked a little, but I'd like to beef it up a little, as the crack
> will move if pressure is put on it.
>
> Taping up the crack isn't so great, as it seems something with
> compressional strength -- which packing tape does not have. But
> fiberglass would do it nicely.
>
> So, I was thinking of using fiberglass, putting a few strips over the
> parts that need repairing. Any thoughts?
>
> I've got some of this stuff --
>
> http://www2.towerhobbies.com/cgi-bin...&I=LXL491&P=ML
>
> is that what I want? I've used regular building epoxy with this in
> the past, and it seemed to work OK, but I'm reading more stuff online
> that says to use something else ...
>
> In the past, when I cut the fiberglass cloth, the ends frayed badly
> and it sort of made a mess. Any way around that?
>
> As I understand it, I should sand a small part around where my repair
> will go so the epoxy will stick better, get it really clean, then put
> everything where I want it (and make sure it doesn't move later), and
> put a few strips of fiberglass saturated with epoxy on it, and let it
> all set. Once it's all done, sand it smooth and paint if I want.
>
> Anything else?
>



You don't have to use epoxy with the fiberglass cloth. You can wrap a
piece of saran wrap around your finger and push medium or thick CA into
the cloth. Saves lots of time. Is usually lighter and is much, much quicker.

Ed Cregger
Old Sep 16, 2007, 11:23 PM
Dan_Thomas_nospam@yahoo.com
Guest
n/a Posts
Re: Repair with fiberglass?


> Doug McLaren wrote:


>
> > is that what I want? I've used regular building epoxy with this in
> > the past, and it seemed to work OK, but I'm reading more stuff online
> > that says to use something else ...

>
> > In the past, when I cut the fiberglass cloth, the ends frayed badly
> > and it sort of made a mess. Any way around that?


Really sharp scissors, and cut it on an angle, not along the
warp or woof. Patches cut with the threads running at 45=B0 across them
will conform to compound curves, too.
Polyester resin (fiberglassing resin) will eat some plastics.
If your airplane is made of foam or styrene or acrylic or ABS, don't
use it. Epoxy is safer.

Dan

Old Sep 18, 2007, 10:31 AM
bm459@scn.org
Guest
n/a Posts
Re: Repair with fiberglass?

On 15 Sep, 19:57, "Doug McLaren" <dougmc+usenet-20070...@frenzied.us>
wrote:
> I've bot a Bird of Time ARF that was crashed that I want to repair.
>
> The nose was smashed up nicely, and there's some cracks in the
> fuselage. Pictures at
>
> http://mclarenhome.com/~dougmc/RC/bot-repair/
>
> Now, as far as repairs go, this is a simple one. The nose is pretty
> bad off, but I could fix it with strapping tape if I wanted to do a
> half-assed job of it. And the fuse is still reasonably strong where
> it cracked a little, but I'd like to beef it up a little, as the crack
> will move if pressure is put on it.
>
> Taping up the crack isn't so great, as it seems something with
> compressional strength -- which packing tape does not have. But
> fiberglass would do it nicely.
>
> So, I was thinking of using fiberglass, putting a few strips over the
> parts that need repairing. Any thoughts?
>
> I've got some of this stuff --
>
> http://www2.towerhobbies.com/cgi-bin...&I=LXL491&P=ML
>
> is that what I want? I've used regular building epoxy with this in
> the past, and it seemed to work OK, but I'm reading more stuff online
> that says to use something else ...
>
> In the past, when I cut the fiberglass cloth, the ends frayed badly
> and it sort of made a mess. Any way around that?
>
> As I understand it, I should sand a small part around where my repair
> will go so the epoxy will stick better, get it really clean, then put
> everything where I want it (and make sure it doesn't move later), and
> put a few strips of fiberglass saturated with epoxy on it, and let it
> all set. Once it's all done, sand it smooth and paint if I want.
>
> Anything else?
>
> --
> Doug McLaren, dou...@frenzied.us
> The beatings will continue until morale improves!


Fill in any gouges with some filler and smooth the surface. I like
wall board compound. Let it dry real well before sanding. If needed,
prestabalize the break with a drop of CA to make the structure rigid
while you work on it. Your final surface will be no better then what
you start with so get it smooth before you get out the epoxy.

Cut the glass cloth on the bias to reduce fraying to a minimum. It is
better to use two or four layers of a light cloth vs one layer of
heavier cloth to get smooth fits. Use a finishing epoxy for the best
results. Stuff like ZPoxy is real easy to work with. West system
products are too viscous for best results in model work. They will
work but are a pain in the ....... Rough the whole surface you are
bonding to then just wet it with epoxy and lay the cloth over the wet
surface. Work just enough epoxy into the cloth to wet it out then lay
the second layer over it. Work on the second layer with a plastic
tool you can get at any auto parts store or an old credit card for
putting on body putty to work excess epoxy into the second layer.
Usually what you put down to wet the first layer is enough to wet a
second layer also. Clean the card right after use with acetone or MEK
or you will only use it once. Ethanol will also work but is slower
and not as good.

Finally cover the whole area with peal ply. Peal ply is simply a
polyester cloth. I have used scraps of polyester woven cloth from my
wifes sewing bin in emergencies and it works fine. If you have a big
bend in the part being patched it will work better then the heavier
commercial peal ply. Let it cure 24 hours or more and peal off the
peal ply and you will have a smooth surface. Much smoother then you
can get with a regular layup. You need enough epoxy in the glass to
wet the peal ply out fairly well. But beginners always have more then
enough epoxy that this is not a problem. Make sure it is polyester if
you are using scrap cloth. Easy to do by testing and seeing if it
will peal off the cured surface cleanly. Any cotton in the cloth will
be a disastor.

Will the patch be invisiable? Nope. But it will not have rough edges
and splinters sticking out that will grab a hunk out of your hand like
a fish hook. And there is no stronger patch you can make for the tiny
weight you added unless you go to carbon cloth. This will work on any
plastic or wood.

Fast, very strong, easy, neat. I have stuck a fuse busted clear in
half back together this way and been flying in 48 hours.

Old Sep 18, 2007, 05:22 PM
Morgans
Guest
n/a Posts
Re: Repair with fiberglass?


<bm459@scn.org> wrote

> Fill in any gouges with some filler and smooth the surface. I like
> wall board compound.


Good recommendations. One thing though, is your recommendation of wallboard
filler compound.

It is heavy, and lightweight spackling compound works as well, and is much
lighter. Have you ever tried it before?
--
Jim in NC


Old Sep 18, 2007, 09:09 PM
bm459@scn.org
Guest
n/a Posts
Re: Repair with fiberglass?

On 18 Sep, 17:22, "Morgans" <jsmor...@charterJUNK.net> wrote:
> <bm...@scn.org> wrote
>
> > Fill in any gouges with some filler and smooth the surface. I like
> > wall board compound.

>
> Good recommendations. One thing though, is your recommendation of wallboard
> filler compound.
>
> It is heavy, and lightweight spackling compound works as well, and is much
> lighter. Have you ever tried it before?
> --
> Jim in NC


Whatever the stickum you use to cover screws and fill the seams
between hunks of wall board is what I have used. If you are filling
enough gouges that it will take more then five grams dry weight you
have not done much of a job of lining up the original busted parts.
If you have a hole slap a hunk of real thin balsa behind it and use
the stickum to smooth it out. Make sure it is fully dry before you
sand it to shape. Maybe the stickum is spackling compound? Beats
me. Buy a gallon and it will be spoiled long before you use it all
but a gallon only costs a few bucks.

Old Sep 18, 2007, 10:38 PM
Morgans
Guest
n/a Posts
Re: Repair with fiberglass?


<bm459@scn.org> wrote

> Whatever the stickum you use to cover screws and fill the seams
> between hunks of wall board is what I have used.


Called joint compound.

>If you are filling
> enough gouges that it will take more then five grams dry weight you
> have not done much of a job of lining up the original busted parts.


True, but you know as well as me, that all weight counts against you. There
is a lighter alternative, is my message.

> If you have a hole slap a hunk of real thin balsa behind it and use
> the stickum to smooth it out. Make sure it is fully dry before you
> sand it to shape. Maybe the stickum is spackling compound?


Nope. You need to go to the hardware store and look in the area where they
have nail filler putty and stuff. Lightweight spackle is used mainly for
filling nail holes, and repairing small defects in walls. It is probably a
quarter of the weight than the stuff you use, and acts almost the same,
except that it is TONS easier to sand. The common size is probably around a
pint or less, usually in a white plastic pop top container.

> Beats me. Buy a gallon and it will be spoiled long before you use it all
> but a gallon only costs a few bucks.


True.

Try some, sometime. It is great stuff. You can make it even tougher by
getting it sanded into shape after it dries (and that is another big
advantage; it dries in a tenth of the time) and then flooding it with CA
thin glue. It is much more porous than regular joint compound, so it wicks
up the CA great.
--
Jim in NC


Old Sep 19, 2007, 04:30 AM
Ed Cregger
Guest
n/a Posts
Re: Repair with fiberglass?


"Morgans" <jsmorgan@charterJUNK.net> wrote in message
newsZ%Hi.111$zy3.91@newsfe02.lga...
>
> <bm459@scn.org> wrote
>
>> Whatever the stickum you use to cover screws and fill the seams
>> between hunks of wall board is what I have used.

>
> Called joint compound.
>
>>If you are filling
>> enough gouges that it will take more then five grams dry weight you
>> have not done much of a job of lining up the original busted parts.

>
> True, but you know as well as me, that all weight counts against you.
> There is a lighter alternative, is my message.
>
>> If you have a hole slap a hunk of real thin balsa behind it and use
>> the stickum to smooth it out. Make sure it is fully dry before you
>> sand it to shape. Maybe the stickum is spackling compound?

>
> Nope. You need to go to the hardware store and look in the area where
> they have nail filler putty and stuff. Lightweight spackle is used mainly
> for filling nail holes, and repairing small defects in walls. It is
> probably a quarter of the weight than the stuff you use, and acts almost
> the same, except that it is TONS easier to sand. The common size is
> probably around a pint or less, usually in a white plastic pop top
> container.
>
>> Beats me. Buy a gallon and it will be spoiled long before you use it all
>> but a gallon only costs a few bucks.

>
> True.
>
> Try some, sometime. It is great stuff. You can make it even tougher by
> getting it sanded into shape after it dries (and that is another big
> advantage; it dries in a tenth of the time) and then flooding it with CA
> thin glue. It is much more porous than regular joint compound, so it
> wicks up the CA great.
> --
> Jim in NC
>



I use regular "heavy" spackling. I can't explain why, but I don't care for
the light weight spackling. Joint compound is too difficult to sand when
spackling is available.

I should say that I don't suffer a weight penalty with heavy spackling
because I fill in all medium to large voids with scraps of balsa, then
resand until the surface is very smooth. Then I use the heavy spackling,
but, again, I sand it off so that only small white streaks of spackling are
visible. Most of my filling is done with light weight balsa.

Ed Cregger


Old Sep 19, 2007, 04:51 AM
Morgans
Guest
n/a Posts
Re: Repair with fiberglass?


"Ed Cregger" <ecregger@bellsouff.net> wrote

> I should say that I don't suffer a weight penalty with heavy spackling
> because I fill in all medium to large voids with scraps of balsa, then
> resand until the surface is very smooth. Then I use the heavy spackling,
> but, again, I sand it off so that only small white streaks of spackling
> are visible. Most of my filling is done with light weight balsa.


That is another good way to go.

More than one way to skin a rabbit, a wise man told me!
--
Jim in NC


Old Sep 19, 2007, 01:18 PM
MJKolodziej
Guest
n/a Posts
Re: Repair with fiberglass?


"Morgans" <jsmorgan@charterJUNK.net> wrote in message
newsq5Ii.254$zy3.219@newsfe02.lga...
>
> "Ed Cregger" <ecregger@bellsouff.net> wrote
>
>> I should say that I don't suffer a weight penalty with heavy spackling
>> because I fill in all medium to large voids with scraps of balsa, then
>> resand until the surface is very smooth. Then I use the heavy spackling,
>> but, again, I sand it off so that only small white streaks of spackling
>> are visible. Most of my filling is done with light weight balsa.

>
> That is another good way to go.
>
> More than one way to skin a rabbit, a wise man told me!
> --
> Jim in NC


Along those lines, I like micro ballons in Ambroid or Sigment. I also have
some pre-mixed stuff that dried out long ago. You can put micro ballons in
fiberglass resin but there's that sanding part........
mk




Old Sep 19, 2007, 07:40 PM
Vance Howard
Guest
n/a Posts
Re: Repair with fiberglass?

Morgans wrote:

>
> Try some, sometime. It is great stuff. You can make it even tougher by
> getting it sanded into shape after it dries (and that is another big
> advantage; it dries in a tenth of the time) and then flooding it with CA
> thin glue. It is much more porous than regular joint compound, so it wicks
> up the CA great.


So you use light weight spackling to save weight, then add weight with
CA to harden it up. Might as well use the regular stuff.
Old Sep 19, 2007, 11:42 PM
Morgans
Guest
n/a Posts
Re: Repair with fiberglass?


"Vance Howard" <> wrote

> So you use light weight spackling to save weight, then add weight with
> CA to harden it up. Might as well use the regular stuff.


No, I usually do not. I just included that tip in case the repair was in a
place that needed extra strength.

The heavy stuff would not be as tough without adding the CA, as the
lightweight stuff with the CA, also.

Hey, it is just a suggestion, that I have found to be useful at times. I
especially like using it on sheet balsa areas that are going to be covered
with Monocote, or something like it. The finish of your Monocote is only as
good as the surface underneath it. (but you knew that)
--
Jim in NC


Old Sep 20, 2007, 04:17 PM
Ed Cregger
Guest
n/a Posts
Re: Repair with fiberglass?

MJKolodziej wrote:
> "Morgans" <jsmorgan@charterJUNK.net> wrote in message
> newsq5Ii.254$zy3.219@newsfe02.lga...
>> "Ed Cregger" <ecregger@bellsouff.net> wrote
>>
>>> I should say that I don't suffer a weight penalty with heavy spackling
>>> because I fill in all medium to large voids with scraps of balsa, then
>>> resand until the surface is very smooth. Then I use the heavy spackling,
>>> but, again, I sand it off so that only small white streaks of spackling
>>> are visible. Most of my filling is done with light weight balsa.

>> That is another good way to go.
>>
>> More than one way to skin a rabbit, a wise man told me!
>> --
>> Jim in NC

>
> Along those lines, I like micro ballons in Ambroid or Sigment. I also have
> some pre-mixed stuff that dried out long ago. You can put micro ballons in
> fiberglass resin but there's that sanding part........
> mk


-------------

Now that we're talking about fillers, I like to use phenolic micro
balloons (brownish) for making fillets. I've used epoxy and polyester
resin as a binder. I'll have to try Ambroid or Sigment. Never thought of
trying that before.

It seems to me that there was one spackling product that negatively
reacted when used with either polyester resin or epoxy resin, but I
can't remember which one it was. Anyone?

Ed Cregger
 


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