6-min epoxy vs. 30-min epoxy
Gravanti
What's the difference?...other than the obvious...curing time 6 min vs 30
min <G>
--
Fly on!
Gravanti
--
The secret to keep from crashing: Simply forget to hit the ground.
(send all responses to this newsgroup so
all can benefit from this discussion)
Chris Sorgatz
In article <33c3be03...@news.pacifier.com>, NSS_gr...@pacifier.com
(Gravanti) writes:
> What's the difference?...other than the obvious...curing time 6 min vs 30
> min <G>
> --
> Fly on!
> Gravanti
> --
> The secret to keep from crashing: Simply forget to hit the ground.
The faster curing epoxies are going to be more brittle. There are very few
places to use 6 minute epoxy. These types of bonding methods are good
for Static modelers who want to attach lots of peices to a model in a short
time frame.
30 minute epoxy is the shortest length epoxy I would use on an aircraft
that is going to seek flight. AND then again, I've even decided that
the longer curing epoxy's are TOO brittle.
The last 1/4 scale plane I built, I used CA at all balsa joints, Titebond
(Alphatic wood glue) on the firewall and landing gear supports, and epoxy
ONLY to set the fiberglass on the wing and fuse. This epoxy was a "finishing"
material that I thinned by about 40% with paint thinner. This is great for
running over fiberglass cloth. Then I take a nylon material called "peel ply"
and lay over the wet epoxy to fill the weave.
Thru my experiences and others in the field with alot more experience than
I, I've found that expoy is not the _Save-all_ for airplane modelers.
Chris
Real planes don't have to have 2 wings and a round motor!
Though it seems to help them glide better!
<><><><><><><><><><><><><><><><><><><><><><><><><><><><>
<> Christopher D. Sorgatz <> csor...@ford.com <>
<> Product Design <> Livonia, Michigan USA <>
<> PTO, Ford Motor Company <> Phone #(313) 266-8852 <>
<><><><><><><><><><><><><><><><><><><><><><><><><><><><>
Support your local IMAA chapter!!!!
These are NOT the views of Ford Motor Co.
Fred Herrmann
The long setting epoxies tend to end up with a harder and stronger set.
In article <33c3be03...@news.pacifier.com>, NSS_gr...@pacifier.com
says...
>
>What's the difference?...other than the obvious...curing time 6 min vs 30
>min <G>
>--
>Fly on!
>Gravanti
>--
>The secret to keep from crashing: Simply forget to hit the ground.
>
> (send all responses to this newsgroup so
> all can benefit from this discussion)
--
"If it doesn't kill you, it will only make you stronger!"
Visit Fred's Semi-Live WebCam and R/C Videos
http://fly.hiwaay.net/~fherrman
Fred Herrmann
In article <5q0k5q$c0...@eccws1.dearborn.ford.com>, csor...@tc2941.pto.ford.com
says...
>The faster curing epoxies are going to be more brittle. There are very few
>places to use 6 minute epoxy. These types of bonding methods are good
>for Static modelers who want to attach lots of peices to a model in a short
>time frame.
>
>30 minute epoxy is the shortest length epoxy I would use on an aircraft
>that is going to seek flight. AND then again, I've even decided that
>the longer curing epoxy's are TOO brittle.
>
>The last 1/4 scale plane I built, I used CA at all balsa joints, Titebond
>(Alphatic wood glue) on the firewall and landing gear supports, and epoxy
>ONLY to set the fiberglass on the wing and fuse. This epoxy was a "finishing"
>material that I thinned by about 40% with paint thinner. This is great for
>running over fiberglass cloth. Then I take a nylon material called "peel ply"
>and lay over the wet epoxy to fill the weave.
>
>Thru my experiences and others in the field with alot more experience than
>I, I've found that expoy is not the _Save-all_ for airplane modelers.
>
>
>Chris
I have to disagree.. I'm no expoxy expert, but my experience is that the
short setting epoxies tend to be more flexible. If I'm really looking for
increased strength in the long setting epoxies I will mix in some milled glass
fiber. I'm not sure what the increased % strength of fiber reinforced epoxy
is, but I'm sure its worth its weight.
I'm certain there is an epoxy expert out there that can set us straight on
this..
Matthew S Greenlaw
csor...@tc2941.pto.ford.com (Chris Sorgatz) writes:
>In article <33c3be03...@news.pacifier.com>, NSS_gr...@pacifier.com
>(Gravanti) writes:
>> What's the difference?...other than the obvious...curing time 6 min vs 30
>> min <G>
>> --
>> Fly on!
>> Gravanti
>> --
>> The secret to keep from crashing: Simply forget to hit the ground.
>The faster curing epoxies are going to be more brittle. There are very few
>places to use 6 minute epoxy. These types of bonding methods are good
>for Static modelers who want to attach lots of peices to a model in a short
>time frame.
>30 minute epoxy is the shortest length epoxy I would use on an aircraft
>that is going to seek flight. AND then again, I've even decided that
>the longer curing epoxy's are TOO brittle.
<SNIP>
This is a huge generalization. Most epoxy characteristics are "brand
specific" and vary depending on the type you use. I usually use Z-poxy,
but have used some Bob Smith recently with excellent results. If you
read his literature about glues, his 5-minute is actually the most
flexible epoxy he offers. His strongest is the 30 minute, which (as you
mentioned) is more brittle, but STRONGER. My recommendation would be to
try a few different types and see what you like. For all practical
purposes, you can use whatever "speed" epoxy is convenient--the strength
is pretty close. I would challenge the average modeler to tell me
whether a cured epoxy was a 30 minute mix or a quick 5 minute epoxy.
>The last 1/4 scale plane I built, I used CA at all balsa joints, Titebond
>(Alphatic wood glue) on the firewall and landing gear supports, and epoxy
>ONLY to set the fiberglass on the wing and fuse. This epoxy was a "finishing"
>material that I thinned by about 40% with paint thinner. This is great for
>running over fiberglass cloth. Then I take a nylon material called "peel ply"
>and lay over the wet epoxy to fill the weave.
I would imagine the thinned epoxy would have greatly reduced
strength. In addition, I would NEVER use epoxy as a thinner for epoxy.
A more suitable solvent/thinner is acetone or denatured alcohol. Even
then, adverse weakening of the resin could result. I would not recommend
it for a layup where strength (heck, even cosmetics) is an issue.
--
Matthew Greenlaw Mechanical Engineering
Mgr...@Hubcap.Clemson.Edu Clemson University
http://hubcap.clemson.edu/~mgreenl Clemson, South Carolina
Currently on co-op assignment in Florence, SC with E.I. DuPont.
all...@erols.com
TO throw my two cents in on the great 5 min/30 min epoxy debate. I have
used both over the years (30+) but have pretty much so abandoned 5 min
due to a problem I ran into last summer with my Falcon 56. Was out at
the local field when all of a sudden the wing and fuselage parted
company. Fuse looked like an ICBM on final. Fortunately the ground was
somewhat soft and I collected all the pieces and examined it. What
had happened was that the wing hold down dowel support, that had been
glued with 5 min had turned to rubber and pulled out. I examined all
the other 5 min joints and everyone had deteriorated and become like
rubber, I could pull it off like a rubber band. Pulled apart all the
joints and reglued everything with 30 min. Fixed the engine (OS40
Surpass) and the plane is flying again. That episode swore me off 5
min.
One thing to keep in mind is that the model epoxies we use are very
sensitive to correct mixing proportions and mixing. A variation as
little as 10 percent can have major effects on the cure rate (don't add
more hardener to speed the cure!) and overall final strength. For those
who are interested Jerry Nelson has an excellent article on epoxies in
his catalog. Brian Allen
--
MZ?
Ian Maclaughlin
NSS_gr...@pacifier.com (Gravanti) wrote:
>What's the difference?...other than the obvious...curing time 6 min vs 30
>min <G>
What other difference than the obvious would matter?
Ian
San Diego
Bill Calkins
Gravanti wrote:
>
> What's the difference?...other than the obvious...curing time 6 min vs 30
> min <G>
> Fly on!
> Gravanti
> --
> The secret to keep from crashing: Simply forget to hit the ground.
>
> all can benefit from this discussion)
time, rather that is how long the glue joint lasts. ;-)
Actually I use 5 minute epoxy, but when I really need the strength,
motor mounts, landing gear blocks or structural repairs, then I use the
overnight stuff. Waiting a whole day is a lot better than having to
rebuild the kit....
--
================================================================
Bill Calkins
Interested in C/L?
Check out this page: http://pwp.starnetinc.com/clflyer
================================================================
Red Scholefield
On Wed, 9 Jul 1997, Gravanti wrote:
> What's the difference?...other than the obvious...curing time 6 min vs 30
> min <G>
> --
The longer the cure time the more strength - rule of thumb, mileage will
vary on different brands.
One reason stated is that longer cureing allows the epoxy to penetrate the
material being joined. If you are joining two pieces of metal - find
another reason. G>
Red S.
Matthew S Greenlaw
mgr...@hubcap.clemson.edu (Matthew S Greenlaw) writes:
> I would imagine the thinned epoxy would have greatly reduced
>strength. In addition, I would NEVER use epoxy as a thinner for epoxy.
^^^^^
Oops, I meant, "I would never use paint thinner as a reducer for
epoxy. :)
Jerel Zarestky
Gravanti wrote:
>
> What's the difference?...other than the obvious...curing time 6 min vs 30
> min <G>
It looks like folks have covered most of the differences. Many times it
depends on the brand of epoxy. I've had 5-minute epoxy that retains
some flexibility after curing and some that is rock hard and has lasted
20 years (I guess that brand isn't available anymore).
I do use the longer setting epoxy for all firewall joints for the same
reason Red mentioned; it soaks into the ply for a stronger joint. Most
5-6 minute epoxies will stay more on the surface.
Jerel
--
"Keep away from people who try to belittle your ambitions. Small people
always do that, but the really great make you feel that you too can
become great."
~ Mark Twain
Jerel Zarestky
Neutron Scattering Group
Ames Laboratory / ISU @ Oak Ridge National Laboratory
http://neutrons.ornl.gov/
Fred Herrmann
In article <mgreenl.868478999@hubcap>, mgr...@hubcap.clemson.edu says...
>In addition, I would NEVER use epoxy as a thinner for epoxy.
>A more suitable solvent/thinner is acetone or denatured alcohol. Even
>then, adverse weakening of the resin could result. I would not recommend
>it for a layup where strength (heck, even cosmetics) is an issue.
All I can say is Amen to this last statement... Many years ago, when I was a
mere highschool student I ran out of long setting epoxy.. My thinking was that
epoxy must be epoxy, so I started mixing some 5 min epoxy with the long setting
epoxy and proceeded to glue in the brass wing tubing for my Olympic glider
(this was in 1971). On the second launch the wing folded. The epoxy had the
consistancy of a wet rubber band.. Been there, done that, don't you do it.
Fred Herrmann
I still haven't seen any numbers or discussion on the strength advantage of
fiber reinforced epoxy. Must be some numbers out there some where?
Jason Werner
Matthew S Greenlaw wrote:
>
>
> This is a huge generalization. Most epoxy characteristics are "brand
> specific" and vary depending on the type you use. I usually use Z-poxy,
> but have used some Bob Smith recently with excellent results. If you
> read his literature about glues, his 5-minute is actually the most
> flexible epoxy he offers. His strongest is the 30 minute, which (as you
> mentioned) is more brittle, but STRONGER. My recommendation would be to
> try a few different types and see what you like. For all practical
> purposes, you can use whatever "speed" epoxy is convenient--the strength
> is pretty close. I would challenge the average modeler to tell me
> whether a cured epoxy was a 30 minute mix or a quick 5 minute epoxy.
>
Matthew,
Remember your composites clases? Strength of epoxy is measured in
several ways, compression, tension, and hardness. Normally a stronger
(tension and compression) epoxy is also a little more brittle (harder).
A flexible epoxy is normally a little softer in hardness and also a
little less strong. Even so, the cure time normally has very little to
do with the strength. The 30 vs 5 minute bond becomes a factor when
joining materials. A 30 minute epoxy will generally form a better bond
due to several things. First of all a 30 min epoxy is normally
thinner. This allows a better "wetting" of the surface. On balsa it
allows better penetration into the wood grain, on fiberglass a more
complete matrix can be formed and less imperfections will exist.
Secondly, since 30 minute is thinner...less epoxy can be used in a
composite situation. This actually allows for a stronger joint in that
the brittle nature on epoxy in minimized by having a thinner suface.
> I would imagine the thinned epoxy would have greatly reduced
> strength. In addition, I would NEVER use epoxy as a thinner for epoxy.
> A more suitable solvent/thinner is acetone or denatured alcohol. Even
> then, adverse weakening of the resin could result. I would not recommend
> it for a layup where strength (heck, even cosmetics) is an issue.
> --
I agree that there is better thinners to be used. In his example
though, the thinning is actually going to form a better bond. The
strength of the material is formed by the fiberglass, not the resin.
Thinner epoxy will allow a better "wetting" of the composite and allow a
lighter more flexible joint. This is exactly what is wanted in a
fiberglassing situation.
Jason Werner
Don Sudbury
Fred Herrmann <fher...@hiwaay.net> wrote in article
<5q2s0m$72g$2...@hammer.msfc.nasa.gov>...
I'll see If I can provide some. I know some individuals that work in R&D
and test various epoxy compounds. They may be able to give me some
non-proprietary information that I can post.
Don
AMA 30570
Brad Benson
fher...@hiwaay.net (Fred Herrmann) wrote:
] I have to disagree.. I'm no expoxy expert, but my experience is that the
] short setting epoxies tend to be more flexible. If I'm really looking for
] increased strength in the long setting epoxies I will mix in some milled glass
] fiber. I'm not sure what the increased % strength of fiber reinforced epoxy
] is, but I'm sure its worth its weight.
I agree completely; the 30 minute stuff I've used sure seems more
brittle than th 5 minute variety (Zap Z*Poxy).
I also like the milled glass fiber, and use it *almost* every time I
use epoxy. Since the milled fiber weighs less than the epoxy it
displaces, it doesn't really increase the weight of the joint at
all...
Cheers,
Brad
Michael A. McEvilley
Fred Herrmann wrote:
>
> I still haven't seen any numbers or discussion on the strength advantage of
> fiber reinforced epoxy. Must be some numbers out there some where?
>
> --
> "If it doesn't kill you, it will only make you stronger!"
> Visit Fred's Semi-Live WebCam and R/C Videos
>
No numbers, but my understanding is that the fibers increase the shear
strength, thereby making the joint more resistant to vibration-induced
failure. I learned about using milled fiber from the ducted fan guys.
-michael
Chris Sorgatz
In article <5q2rq9$72g$1...@hammer.msfc.nasa.gov>, fher...@hiwaay.net (Fred
> >A more suitable solvent/thinner is acetone or denatured alcohol. Even
> >then, adverse weakening of the resin could result. I would not recommend
> >it for a layup where strength (heck, even cosmetics) is an issue.
>
> > mere highschool student I ran out of long setting epoxy.. My thinking was
> that
> epoxy must be epoxy, so I started mixing some 5 min epoxy with the long
> setting
> epoxy and proceeded to glue in the brass wing tubing for my Olympic glider
> (this was in 1971). On the second launch the wing folded. The epoxy had the
> > consistancy of a wet rubber band.. Been there, done that, don't you do it.
Fred,
While I agree with your statement, that was NOT what Matt was trying
to say. He was trying to tell everyone that "Paint thinner" was something
he would NEVER use to thin epoxy. Paint thinner is actually a good
thinning agent for spreading epoxy over fiberglass. I'm REALLY surprised
that no one is picking up on this.
Chris
<><><><><><><><><><><><><><><><><><><><><><><><><><><><>
<> Christopher D. Sorgatz <> csor...@ford.com <>
<> Product Design <> Livonia, Michigan USA <>
<> PTO, Ford Motor Company <> Phone #(313) 266-8852 <>
<><><><><><><><><><><><><><><><><><><><><><><><><><><><>
Catch 22:
Following the rules will never get the job done!
Getting the job done is no excuse for not following the rules!
Paul W.
Fred,
What is "milled glass fiber?" Do you just unravel some plain
fiberglass cloth or is it something sold in bulk? Do you have a brand
name or source? I strongly agree with you that glue alone will not
always do the whole job. Sometimes additional structural material is
needed and adding fiberglass to an epoxy joint can only make the joint
stronger.
Waiting to hear. Paul.
On 9 Jul 1997 19:49:59 GMT, fher...@hiwaay.net (Fred Herrmann) wrote:
>If I'm really looking for
>increased strength in the long setting epoxies I will mix in some milled glass
>fiber. I'm not sure what the increased % strength of fiber reinforced epoxy
>is, but I'm sure its worth its weight.
>
> http://fly.hiwaay.net/~fherrman
Paul W.
Chris,
Does "Ply-Peel" have a brand name? Where do you get it? Being
nylon does the epoxy grab it or can you/do you peel it off after the
epoxy dries? And pardon my ignorance on this one: where are you using
fiberglass cloth that you need to "fill the weave" in this fashion?
My experience has been to let the epoxy dry, sand it lightly and
repeat until the weave is history. Your solution sounds intriguing
and I might like to try it.
I look forward to your response. Paul.
========================================================
On 9 Jul 1997 18:10:02 GMT, csor...@tc2941.pto.ford.com (Chris
gosc...@real3d.com
In article <5q0k5q$c0...@eccws1.dearborn.ford.com>,
csor...@tc2941.pto.ford.com (Chris Sorgatz) wrote:
> 30 minute epoxy is the shortest length epoxy I would use on an aircraft
> that is going to seek flight. AND then again, I've even decided that
> the longer curing epoxy's are TOO brittle.
>
-SNIP-
>
> Thru my experiences and others in the field with alot more experience than
> I, I've found that expoy is not the _Save-all_ for airplane modelers.
>
> Chris
I agree that epoxy is not a _Save-all_. However, I think it has more to do
with the skill and knowledge (or lack of) of the average modeler about
epoxy use than actual failures of epoxy when used as intended. I think the
attitude that it is a _Save-all_ is what contributes to its mis-use.
First, I think five minute epoxies do have a bit less strength than
longer cure epoxies. From what I've seen though, this in itself should
not be a problem. Any reasonably well designed airplane should not apply
stresses anywhere near the limit of a well made glue joint. I think
another inherent feature of the five minute type is a low resistance to
glow-fuel. It will tend to soften when repeatedly exposed to glow-fuel.
Much of the problem, I think, is that many modelers consider 5-minute
epoxy to be a convenience without realizing the limitations. Obviously,
since it cures fast you need to work fast. So, many modelers will skimp
on mixing time. This is not how to save time. The batch should be mixed
for about 45 sec to 1 minute. If you don't get a well mixed batch, you
risk epoxy that won't fully cure, or it might cure to a rubbery
consistency. This leaves 4 minutes to finish the joint. Looking ahead,
you would need to reserve at least a minute to postion, clamp, weight,
etc. the pieces involved in the joint. This leaves about 3 minutes to
apply epoxy and wet out the joint. Once the glue just barely starts to
thicken, if you haven't set the joint already, you have started losing
joint strength. The glue will no longer bond as strongly to whatever
surface as it would have if applied while completely fluid. We all know
how time flies in the workshop, so that 3 minutes of true working time
will go by fast. If you don't get set in that amount of time, you are
making a weak joint. It's not the epoxies' fault, it's working as
advertised.
I myself use 5 minute epoxy wherever possible on any airplane up to .60
size. Of course, since I understand the short working time available, I
prepare the joint completely before mixing epoxy. This way, once I
complete the joint, I can usually set it down for another five minutes
and then pick up the piece and continue work.
I wouldn't use 5-min epoxy on anything bigger than a .60 size just bacause
of the relative sizes. Bigger airplanes - bigger glue joints, means more
time required to properly wet-out the joint. This means there is less
chance that the joint will cure properly for full strength.
TUNE IN NEXT TIME - debunking the myth that epoxy unnecessarily increases
the weight of an aircraft. :)
John
-------------------==== Posted via Deja News ====-----------------------
http://www.dejanews.com/ Search, Read, Post to Usenet
Jason Werner
Paul,
Epoxy is not really designed to provide structural strength. Yes it
dos work, but it is much better to use epoxy to hold togethor the load
bearing pieces. That is why you want to use as little epoxy in
fiberglass as possible. Vac. bagging allows you to compress the epoxy
into the fiberglass weave, allowing a lightweight yet smooth finish.
The milled glass fiber adds strength to the fiberglass. Remember, epoxy
is HEAVY, use as little as possible to make a light weight plane.
Weight vs strength is everything. Large filleted joints may be strong,
but a well cut glued joint is just as strong and a lot lighter.
Jason werner
Jason Werner
Paul W. wrote:
>
> Chris,
> Does "Ply-Peel" have a brand name? Where do you get it? Being
> nylon does the epoxy grab it or can you/do you peel it off after the
> epoxy dries? And pardon my ignorance on this one: where are you using
> fiberglass cloth that you need to "fill the weave" in this fashion?
> My experience has been to let the epoxy dry, sand it lightly and
> repeat until the weave is history. Your solution sounds intriguing
> and I might like to try it.
> I look forward to your response. Paul.
> ========================================================
Paul,
Peel ply is sold by Aerospace Composites (see mag ad). It does not
stick very well to epoxy so you can effectively work it into the epoxy
and then "rip" it off. Light touch up sand and you are done.
Jason werner
Chris Sorgatz
Yes, Aerospace Comp sells it.
You apply it right away, after flowing the epoxy into the fiberglass and
screeting all excess out. Then lay a piece over the working area and work
it onto the fiberglass as tightly as you can. Remove all bubbles. You'll
see the peel-ply begin to saturate this is good because it is filling the
weave if the fiberglass. Leave the peel-ply on until the epoxy is completely
cured. It WILL pull off, though it will SOUND like a 747 is taking off!!!!
At that point, lightly sand with 320 and you'll never have been MORE ready
for paint!!!!!
Chris
Real planes don't have to have 2 wings and a round motor!
Though it seems to help them glide better!
<><><><><><><><><><><><><><><><><><><><><><><><><><><><>
<> Christopher D. Sorgatz <> csor...@ford.com <>
<> Product Design <> Livonia, Michigan USA <>
<> PTO, Ford Motor Company <> Phone #(313) 266-8852 <>
<><><><><><><><><><><><><><><><><><><><><><><><><><><><>
Support your local IMAA chapter!!!!
These are NOT the views of Ford Motor Co.
R. M. Odom
>min <G>
>Fly on!
>Gravanti
>--
>The secret to keep from crashing: Simply forget to hit the ground.
>
> (send all responses to this newsgroup so
> all can benefit from this discussion)
Well, to get a little more picky about it, 6 minute epoxy has a working time of
about 6 minutes and full cure takes much longer. Just because the parts don't
fall apart doesn't mean the epoxy has cured. Even 6 minute epoxy takes overnight
to get almost as hard as it will ever get. Even then, it is not as hard as 1 hour
epoxy after the same overnight cure. My guess is that people that have trouble
with epoxy bonds are not mixing it well enough. You know you have mixed it enough
when your stir stick won't budge. ;-)
richard
Ernie Fidgeon
Hi (again),
Yes, milled glass does increase the strength, you are creating a composite
by adding fibers to resin. However, shear strength may only be increased
marginally. The big benefit of glass fibers is that you create a composite
that benefits from the high stiffness of glass and the damping/compression
strength of resin. The applied loads are distributed into the fibers by
the resin and in the case of milled fiber composites you achieve a stiffer
epoxy in all directions...almost like a metal. This allows you to carry
higher loads that resin alone.
Obviously, unidirectional and woven fabric composites behave differently
but the idea is the same, you create a composite that uses the best of each
individual constituent.
For example, graphite fiber can be as stiff as steel (varies depending on
type) and resin is as stiff as, well, resin, ie- not very. The problem
with graphite is with it's high stiffness it tends to break rather
violently without much warning. If you bond resin into graphite making a
composite, the bonded structure will fracture relatively less violently but
has the ability to redistribute loads around the damage.
There are other pros/cons but this is my general understanding in basic
terms.
Cheers,
EF
Michael A. McEvilley <mmce...@mitretek.org> wrote in article
<33C509...@mitretek.org>...
Ernie Fidgeon
HI,
Milled glass fiber is just that....milled glass fibers, basically ground
into a fine powder. In The compsosite structure repair business we use it
as an additive to epoxy (and other) systems to toughen the cured material
(toughen = make less brittle) and also to improve the handling qualities
when mixing and applying; as you add glass it makes the resin more "pasty"
and that helps if you are trying to use in in awkward places, ie-cavities,
above you etc. One word of caution, if you do use it be sure to wear a
mask and try not to make a mess. If it gets in your skin it is VERY itchy
and I don;t recommend snorting it either (it is glass). When mixing for
aircraft repair we usually use 30-40% parts by weight, ie- 100g mixed
resin, 30-40g milled glass.
Good luck
EF
Paul W. <pa...@cyberdude.com> wrote in article
<33c515cb....@news.dsphere.net>...
Gravanti
In rec.models.rc.air,NSS_gr...@pacifier.com (Gravanti) penned:
>What's the difference?...other than the obvious...curing time 6 min vs 30
>min <G>
Thanks for all the responses! I guess my newsfeed has been getting better.
Supposedly my ISP just upgraded to DIABLO within the last few days. We'll
see just how well it does the next few days.
Once again thanks!
Fred Herrmann
Tower sells it.. Just tell them your looking for milled fiberglass. Its
basically ground up fiberglass.. It would probably be hard to make it as
fine as it needs to be inorder to get a good mix. If they can't find it
email me back and I'll look it up for you.
In article <33c515cb....@news.dsphere.net>, pa...@cyberdude.com
says...
>
>Fred,
> What is "milled glass fiber?" Do you just unravel some plain
>fiberglass cloth or is it something sold in bulk? Do you have a brand
>name or source? I strongly agree with you that glue alone will not
>always do the whole job. Sometimes additional structural material is
>needed and adding fiberglass to an epoxy joint can only make the joint
>stronger.
>Waiting to hear. Paul.
>
>On 9 Jul 1997 19:49:59 GMT, fher...@hiwaay.net (Fred Herrmann) wrote:
>
>>If I'm really looking for
>>increased strength in the long setting epoxies I will mix in some milled
glass
>>fiber. I'm not sure what the increased % strength of fiber reinforced
epoxy
>>is, but I'm sure its worth its weight.
>>
>> http://fly.hiwaay.net/~fherrman
>
--
Visit Fred's Semi-Live Cam and R/C Chat for up to the Minute R/C Updates!
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Jeff Fields
Ernie Fidgeon wrote:
>
> HI,
>
> Milled glass fiber is just that....milled glass fibers, basically ground
> into a fine powder. In The compsosite structure repair business we use it
> as an additive to epoxy (and other) systems to toughen the cured material
> (toughen = make less brittle) and also to improve the handling qualities
> when mixing and applying; as you add glass it makes the resin more "pasty"
> and that helps if you are trying to use in in awkward places, ie-cavities,
> above you etc. One word of caution, if you do use it be sure to wear a
> mask and try not to make a mess. If it gets in your skin it is VERY itchy
> and I don;t recommend snorting it either (it is glass). When mixing for
> aircraft repair we usually use 30-40% parts by weight, ie- 100g mixed
> resin, 30-40g milled glass.
>
> Good luck
> EF
>
> Paul W. <pa...@cyberdude.com> wrote in article
> <33c515cb....@news.dsphere.net>...
> > What is "milled glass fiber?" Do you just unravel some plain
> > fiberglass cloth or is it something sold in bulk? Do you have a brand
> > name or source? I strongly agree with you that glue alone will not
> > always do the whole job. Sometimes additional structural material is
> > needed and adding fiberglass to an epoxy joint can only make the joint
> > stronger.
Several companies sell it now. I just got some from Great Planes. It
comes in an epoxy looking bottle. As Fred wrote be careful wear a
resperator AND eye protection. If this stuff gets into your eyes your
#%$@$!! It gets airborne quickly.
Jeff
Gravanti
In rec.models.rc.air,gosc...@real3d.com penned:
>This leaves about 3 minutes to pply epoxy and wet out the joint.
What does "wet out" mean?
Is there a good way to get the best wet out?
-- ******************************************
Fly on! * send all responses to this newsgroup *
Gravanti * so all can benefit from the discussion *
-- ******************************************
R.Hodgson
Gravanti wrote:
>
> In rec.models.rc.air,gosc...@real3d.com penned:
> >This leaves about 3 minutes to pply epoxy and wet out the joint.
>
> What does "wet out" mean?
>
> Is there a good way to get the best wet out?
Wet out means, were the glue (epoxy) is in a thin enough state to
penetrate the wood. I usually use a pin and poke tiny holes in the wood
to give a "rivet" effect for better adhesion. Note I said TINY. Don't
get carried away. Some people use 80 grit sandpaper to get a good bite
with the glue. This also works well.
Augustus Fink-Nottle
In article <Pine.LNX.3.95.970710...@yoda.fdt.net>,
Red Scholefield <red...@gnv.fdt.net> wrote:
>The longer the cure time the more strength - rule of thumb, mileage will
>vary on different brands.
>
>One reason stated is that longer cureing allows the epoxy to penetrate the
>material being joined. If you are joining two pieces of metal - find
>another reason. G>
>
>Red S.
It's not so much mechanical interlocking as the higher molecular weight that
the epoxy attains in a slow cure that is responsible for the higher strength.
Ofcourse, mechanical interlocking (penetration) will always have a BIG effect
on the joint strength, but that is determined by the viscosity of the resin.
If you have 5-minute and 2 hour epoxy with comparable viscosity, the 2-hour
resin will still have higher strength due to higher mol. wt. This is clearly
seen in epoxy-metal joints where porosity is very low and the contribution of
mechanical adhesion (penetration) is greatly reduced.
regards,
Gussie
Jerry Festa
In article <5q2smh$54...@eccws1.dearborn.ford.com>, csor...@tc2941.pto.ford.com
says...
>
>In article <5q2rq9$72g$1...@hammer.msfc.nasa.gov>, fher...@hiwaay.net (Fred
>Herrmann) writes:
>> In article <mgreenl.868478999@hubcap>, mgr...@hubcap.clemson.edu says...
>>
and he's trad'n his Ranger (AKA Masda)....poor guy....
Jerry
Fred Herrmann
Hey, Just being patriotic and buying American? At least I think it's
American.
BTW,, Chris,,,, do you think you can get me a discount on the new 97' F150
Lariat? I'm looking at the one with the gray leather interior and CD
player. Nice piece of ergonomics. I think that the incorporation of the
Japanese styling was a smart move on Fords' part.. Any help below invoice
price would be appreciated. :-)
In article <5q6l1n$uf3$2...@parlor.HiWAAY.net>, fe...@hiwaay.net says...
--
Dan & Ginger DeVillers
R. M. Odom wrote:
>
<snip>
> You know you have mixed it enough
> when your stir stick won't budge. ;-)
>
> richard
That's my method!
--
Dan & Ginger
To reply via E-mail, remove the *nospam* from our address!
C-ya
Red Scholefield
On Fri, 11 Jul 1997, Augustus Fink-Nottle wrote:
> It's not so much mechanical interlocking as the higher molecular weight that
> the epoxy attains in a slow cure that is responsible for the higher strength.
> Ofcourse, mechanical interlocking (penetration) will always have a BIG effect
> on the joint strength, but that is determined by the viscosity of the resin.
> If you have 5-minute and 2 hour epoxy with comparable viscosity, the 2-hour
> resin will still have higher strength due to higher mol. wt. This is clearly
> seen in epoxy-metal joints where porosity is very low and the contribution of
> mechanical adhesion (penetration) is greatly reduced.
> regards,
> Gussie
Then if viscosity plays a part in the bonding, heating with a heat gun to
make the epoxy flow more would give you a stronger joint. Have I got this
right?
Red
Augustus Fink-Nottle
Red Scholefield <red...@gnv.fdt.net> wrote:
>Then if viscosity plays a part in the bonding, heating with a heat gun to
>make the epoxy flow more would give you a stronger joint. Have I got this
>right?
>Red
Technically, it's a double edged sword. Heating the epoxy to reduce viscosity
will give better penetration and thus higher mechanical adhesion, but the
elevated temperature will cause the initial reaction rate to go up, thus
causing a slight reduction in the molecular weight. So there is a trade off.
But considering the short times for which we heat the epoxy, I don't really
see the reduction in the average molecular weight being very significant. It
depends on the individual system and the materials in the joint.
As an educated guess, I'd say you'll have better "joint strength" if you heat
the epoxy slightly during application to porous (wooden) joints where
penetration plays an important part. In metal joints where the contribution
from mechanical adhesion is low, you might find the overall joint strength
decrease marginally.
regards,
Gussie
Gary Dyrkacz
bhur...@pilot.msu.edu (Augustus Fink-Nottle) wrote:
Although I am not an expert in any glues, its seems to me viscosity is
not the only issue here. The ability of the epoxy to "wet" the wood
is important. Even if the viscosity is low, you could have awful
adhesion if the epoxy doesn't "wet" the wood. If the contact angle of
the the two glues is about equal for wood, then viscosity would be the
most critical parameter..
-
Gary Dyrkacz
dyr...@mcs.net
Learn about Radio Control Aircraft
http://www.mcs.net/~dyrgcmn/
-
Augustus Fink-Nottle
dyr...@mcs.com (Gary Dyrkacz) wrote:
>Although I am not an expert in any glues, its seems to me viscosity is
>not the only issue here. The ability of the epoxy to "wet" the wood
>is important. Even if the viscosity is low, you could have awful
>adhesion if the epoxy doesn't "wet" the wood. If the contact angle of
>the the two glues is about equal for wood, then viscosity would be the
>most critical parameter..
You hit the nail square on it's head. Contact angles are vitally important in
manufacturing any adhesive so as to get good wet out on the substrates they
are meant to be used on. But looking at it from the consumer's perspective,
almost all commercial adhesives have good wetting properties (or they wouldn't
be on the market). The concerns you highlight here are the manufacturer's
headache and they do a pretty good job of giving us adhesives with low contact
angles. As long as the contact angle is well below 90 degrees, we are in safe
country. Since the chemical nature of epoxies is favourable, we get good
'Interfacial Strength' on wood and metal.
The viscosity controls the amount of mechanical adhesion and it is responsible
for a good proportion of the final joint strength. Mind you, I say 'Joint
Strength' and not 'Interfacial Strength' this time. Normally we don't have to
worry about interfacial strength, but the joint strength we routinely improve
on by increasing the roughness (mechanical adhesion).
And to make things even more complicated, lower viscosity can also change
(most often favourably) the contact angle and the surface energy! Now this
opens the avenue for enhancing joint strength by controlling the viscosity.
The down side being the change in the molecular weight of the epoxy. But I
find more often than not that the increase in the bond strength and substrate
strength (wood becomes a high strength wood-epoxy composite when epoxy
penetrates into it) more than offsets the slight decrease in the strength of
the adhesive layer itself.
Oh dash it, I feel like I am still in my lab!
pip-pip,
Gussie
Fred Herrmann
Seeing as I've got to pay off my wifes credit cards first, before I get the
truck, the least I can do is admire a calendar of it. At least she said the
"only" things she bought with the cards were things for the kids. Now where
have we heard that one before?
In article <5qd2ip$jb...@eccws1.dearborn.ford.com>, csor...@tc2941.pto.ford.com
says...
>
>In article <5q6tkr$8uu$1...@parlor.HiWAAY.net>, fher...@hiwaay.net (Fred
Herrmann)
>writes:
>>
>> Hey, Just being patriotic and buying American? At least I think it's
>> American.
>
>There's half the battle, figuring out which components are US....<G>
>
>> BTW,, Chris,,,, do you think you can get me a discount on the new 97' F150
>> Lariat? I'm looking at the one with the gray leather interior and CD
>> player. Nice piece of ergonomics. I think that the incorporation of the
>> Japanese styling was a smart move on Fords' part.. Any help below invoice
>> price would be appreciated. :-)
>
>JAPANESE STYLING??????????? Where in the world did you hear that! <HFG>
>I would be more likely to quote that old woman on a back-dated Chevy
>commercial as saying, "Don't you buy no ugly truck now, ya hear!"
>
>All that aside, I'd be more inclined to give you a set of GM papers, before
>the Ford papers.......<G> I DO have acouple of 1997 Ford truck calenders
>sittin around hear though, I'll mail you one of those if you like? Gotta
>make some more room for my airplane photos. <VBG>
>
>
>Chris
>
>Real planes don't have to have 2 wings and a round motor!
>Though it seems to help them glide better!
>
> <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
> <> Christopher D. Sorgatz <> csor...@ford.com <>
> <> Product Design <> Livonia, Michigan USA <>
> <> PTO, Ford Motor Company <> Phone #(313) 266-8852 <>
> <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
>
> Support your local IMAA chapter!!!!
>
> These are NOT the views of Ford Motor Co.
--
"If it doesn't kill you, it will only make you stronger!"
Visit Fred's Semi-Live WebCam and R/C Videos
http://fly.hiwaay.net/~fherrman
Gordon McConnell
Augustus Fink-Nottle wrote:
>
> Red Scholefield <red...@gnv.fdt.net> wrote:
> >Then if viscosity plays a part in the bonding, heating with a heat gun to
> >make the epoxy flow more would give you a stronger joint. Have I got this
> >right?
> >Red
>
> Technically, it's a double edged sword. Heating the epoxy to reduce viscosity
> will give better penetration and thus higher mechanical adhesion, but the
> elevated temperature will cause the initial reaction rate to go up, thus
> causing a slight reduction in the molecular weight.
So if reduced viscosity is good, but heating the epoxy may not be,
how about when you thin epoxy with e.g denatured alcohol ? How does
that affect the strength of the resultant bond ? Does the alcohol
all just evaporate, or does it take part in, and thus change, the
chemical reaction that we're relying on ?
Gordon
--
To reply by email, remove the anti-spam "not_" from my email id.
AMA 5765 / SFA 71071 / IMAA 21397
Always glad to share my ignorance - I've got plenty.
Chris Sorgatz
In article <5q6l1n$uf3$2...@parlor.HiWAAY.net>, fe...@hiwaay.net (Jerry Festa) writes:
> In article <5q2smh$54...@eccws1.dearborn.ford.com>, csor...@tc2941.pto.ford.com
> says...
> >
> >In article <5q2rq9$72g$1...@hammer.msfc.nasa.gov>, fher...@hiwaay.net (Fred
> >Herrmann) writes:
> >> In article <mgreenl.868478999@hubcap>, mgr...@hubcap.clemson.edu says...
> >>
> Chris, don't critize Fred, he contemplating on purchasing a new FXXX truck -
> and he's trad'n his Ranger (AKA Masda)....poor guy....
You mean we have HOPE for Fred........<grin> Now, If I can just get him to
believe that the Chevy's are better than the F.O.R.D. trucks! I guess I could
start by tellin him that I drive a Chevy........<HFG>
FRED, BUY A CHEVY!!!!!!!!!!!! <<<<<ROTFLMAO>>>>>
Chris Sorgatz
In article <5q6tkr$8uu$1...@parlor.HiWAAY.net>, fher...@hiwaay.net (Fred Herrmann)
writes:
>
> American.
There's half the battle, figuring out which components are US....<G>
> BTW,, Chris,,,, do you think you can get me a discount on the new 97' F150
> Lariat? I'm looking at the one with the gray leather interior and CD
> player. Nice piece of ergonomics. I think that the incorporation of the
> Japanese styling was a smart move on Fords' part.. Any help below invoice
> price would be appreciated. :-)
JAPANESE STYLING??????????? Where in the world did you hear that! <HFG>
I would be more likely to quote that old woman on a back-dated Chevy
commercial as saying, "Don't you buy no ugly truck now, ya hear!"
All that aside, I'd be more inclined to give you a set of GM papers, before
the Ford papers.......<G> I DO have acouple of 1997 Ford truck calenders
sittin around hear though, I'll mail you one of those if you like? Gotta
make some more room for my airplane photos. <VBG>
Augustus Fink-Nottle
In article <33CA300E.381C@not_Synopsys.COM>,
Gordon McConnell <gmc@not_Synopsys.COM> wrote:
>So if reduced viscosity is good, but heating the epoxy may not be,
>how about when you thin epoxy with e.g denatured alcohol ? How does
>that affect the strength of the resultant bond ? Does the alcohol
>all just evaporate, or does it take part in, and thus change, the
>chemical reaction that we're relying on ?
>
> Gordon
Thinning it out will also cause a depression in the strength of the epoxy
itself. See, these cross-linked polymers (epoxy, polyester etc.) consist of
small chains of resin. These chains, when linked together, either by
crosslinking or polycondensation, form large networks which are entangled and
thus become rigid polymers.
Generally there are two basic types of chemical curing agents in the mix -
catalytic and polyfunctional curing agents. The latter will link the epoxide
resin molecules together (making the chain longer) while the former will just
crosslink the short resin chains together. Now we want the resin chains to
link together to get longer higher molecular weight chains. That gives it the
basic strength. Then we also want these chains to crosslink to each other so
that the whole thing becomes rigid.
When we reduce viscosity, either by heating or with some solvent, we are
increasing the mobility of all these chemical entities. All these reactive
groups now find each other much sooner. This will differ for different types
of systems and god knows there are thousands of different ones, but generally
one type of reaction will be faster than the other and most of the time it'll
be the cross-linking reaction that occurs much faster than the condensation.
This essentially gives you a cross-linked material with lower molecular
weight. If we don't reduce viscosity, the crosslinking agents take a long time
to "find" the appropriate reaction sites and this gives the other reaction a
lot of time to occur and give you higher molecular weight. The method of
viscosity reduction does not matter much. It's the increased mobility that
makes the difference.
Am I making any sense?
On top of that, some alcohol groups (-OH) can react with the epoxide group and
thus reduce the number of epoxide groups available for reaction. I have never
used alcohol to thin epoxy, prefering to just heat it a little, but do you
find that thinning with alcohol makes the epoxy a little less rigid? I don't
know the precise reaction mechanism or rates for alcohol and epoxy, but you
should be able to see a slight difference in the end product. Surely some of
the alcohol will eveporate, but some of it should react with the epoxy.
Hmmm... perhaps I'll try this out tonight if I have any epoxy left after the
weekend building spree. Here's an experiment to perform...
Mix some epoxy and add a lot of alcohol to it, not a drop or two... add a
good dollop and let it cure. If the epoxy cures as a rubbery mass (low mol.
wt. and low crosslink density), you know for sure that the alcohol is doing
some dirty work.
regards,
Gussie
Fred Herrmann
In article <5qdpb5$sb...@eccws1.dearborn.ford.com>, csor...@tc2941.pto.ford.com
says...
>I'm not even close to being a scientist, BUT, I do this
>on the BIG BIRDS with gas engines (read: high vibration "mf'ers").
Gee, I've never seen "mufflers" abbreviated this way. I also didn't know they
vibrated. Also never heard of anyone doing "it" on a BIG BIRD either,
especially one with a gas engine. Hope nobody from the Humane Society picks up
on this post.. :-} Maybe all those stories Festa was telling me about those
Ford employees are true?
Fred V. Herrmann
PS: The V. stands for Victorian
Chris Sorgatz
In article <5qdg7q$rj7$1...@msunews.cl.msu.edu>, bhur...@pilot.msu.edu (Augustus
Fink-Nottle) writes:
> In article <33CA300E.381C@not_Synopsys.COM>,
> Gordon McConnell <gmc@not_Synopsys.COM> wrote:
Gussie,
I'm not even close to being a scientist, BUT, you guys are going a step too
far with all your formulas, and jargen. FROM experience, I take a 50% mix
of epoxy and 50% paint thinner (alchol) blend them together, lay the mix on
the fiberglass, and WHAMO! In 24 hours I have an EXCELLENT product! I do this
on the BIG BIRDS with gas engines (read: high vibration mf'ers). The latest
of theses has a thinner, lighter, stronger finish then most. Instead of filling
the weave with epoxy (thru the use of peel-ply) I ran the epoxy REALLY thin
and let it dry. Then after a full cure, I go in and fill the weave with
spackling-compound, let that dry, sand it smooth and smear Balsarite on the
surface. I'm now ready to Monocote, and I have NO build up of epoxy AND
with NO question of strength. The fiberglass is just as strong as any other
method.
I really think that several of you need to investigate your methods.
Chris Sorgatz
<<SNIPPED>>
Gary Dyrkacz
bhur...@pilot.msu.edu (Augustus Fink-Nottle) wrote:
>In article <33CA300E.381C@not_Synopsys.COM>,
> Gordon McConnell <gmc@not_Synopsys.COM> wrote:
>>So if reduced viscosity is good, but heating the epoxy may not be,
>>how about when you thin epoxy with e.g denatured alcohol ? How does
>>that affect the strength of the resultant bond ? Does the alcohol
>>all just evaporate, or does it take part in, and thus change, the
>>chemical reaction that we're relying on ?
>>
>> Gordon
interesting stuff deleted..
>
>This essentially gives you a cross-linked material with lower molecular
>weight. If we don't reduce viscosity, the crosslinking agents take a long time
>to "find" the appropriate reaction sites and this gives the other reaction a
>lot of time to occur and give you higher molecular weight. The method of
>viscosity reduction does not matter much. It's the increased mobility that
>makes the difference.
>
>Am I making any sense?
>
>On top of that, some alcohol groups (-OH) can react with the epoxide group and
>thus reduce the number of epoxide groups available for reaction. I have never
>used alcohol to thin epoxy, prefering to just heat it a little, but do you
>find that thinning with alcohol makes the epoxy a little less rigid? I don't
>know the precise reaction mechanism or rates for alcohol and epoxy, but you
>should be able to see a slight difference in the end product. Surely some of
>the alcohol will eveporate, but some of it should react with the epoxy.
>
>regards,
>Gussie
On the relationship between thinning and rigidity, I have always
wondered what happens to the excess alcohol after the expoxy sets.
Are epoxies porous enough so that the alcohol evaporates away, albeit
slowly, or does it remain trapped in the polymeric matrix. If it does
remain in thre it should affect the glass transition temperature and I
guess that would definitely affect the rigidity, is that the
definition of a plasticizer?
Jerry Festa
In article <5qd7va$9od$1...@hammer.msfc.nasa.gov>, fher...@hiwaay.net says...
>
>Seeing as I've got to pay off my wifes credit cards first, before I get the
>truck, the least I can do is admire a calendar of it. At least she said the
>"only" things she bought with the cards were things for the kids. Now where
>have we heard that one before?
I just talked to her Saturday and the Fun Fly and she mentioned something about
you charging a PLANE and a HiStart at Hobby Lobby....doesn't sound like that
was for the kids (for sure) and SHE doesn't visit Nashville to stop at Hobby
Lobby International! Me thinks you got the story skewed in YOUR favor....now
just wide is a Dodge Truck Vrs. Ford...you gotta git one of dem der looooooog
bed truuuuucks (as they say 'down south')....
Jerry
PS By the way, nice pics in today's newspaper from the Fun Fly (one shot was of
the 1/2 scale Laser 200)...
Augustus Fink-Nottle
Ok, I said yesterday that I would experiment with epoxy and denatured Alcohol
to see what effect it had. The results are here.
I used HobbyPoxy2 epoxy resin (45 minutes working time. 3 hrs curing time) and
ACE "Pure Denatured Alcohol" that I bought last evening.
A word before that for those who think Denatured alcohol is pure alcohol.
It's not. Looking at the list of contents on this can, I see the following
ingredients -
1) Ethanol (Ethyl Alcohol)
2) Methanol (Methyl Alcohol)
3) Isobutyl Ketone
4) Ethyl Acetate
5) Rubber Solvent (god knows what this is - probably benzene/toluene)
6) Water
I had to glass a wing and I used the resin + heat to do the wing surface.
Whatever epoxy was left over was put in a cup and I added about equal amount
of this denatured alcohol to it. Mixed it well and then poured it out into a
flat plate so that there was more than enough surface area for the solvent to
escape.
This morning, the wing was nice and dry. The plate with the thinned epoxy
(remember, it came from the same batch to avoid mixing variation) was slightly
sticky on the surface (normal behaviour - unreacted curing agents migrate to
the surface), but it had also cured. I peeled a bit of it out and it is
RUBBERY. It feels like SILICONE.
My case is proven. If anyone who swears by thinned epoxy retaining the same
properties as regular or heated epoxy wants a sample of this stuff, send me
your address and I'll mail a square inch of it to you. You could also try this
yourself.
I added excess of denatured alcohol to magnify the effect it would have on the
epoxy. In normal practice, you would probably add a little amount and the
effect would be slight and thus not noticeable, especially if the epoxy is
already in the joint. But denatured alcohol WILL and DOES reduce the crosslink
density and molecular weight and thus the final properties of the epoxy.
In the past I've used 70% Isopropyl Alcohol (rubbing alcohol) to prevent
left over epoxy from curing hard in the cup and that too turned into a rubbery
mess allowing easy removal. I had not thought about it then as the effect of
alcohol but rather as the plasticising effect of that 30% water. Denatured
alcohol has a very low percentage of water and this very rubbery material I've
got suggests that the solvents did indeed defunctionalize the epoxy. It could
also be that some of the solvents are still trapped and plasticising the
epoxy.
Next step is to put some of this material in an oven to get rid of all
volatiles and see if it partially restores the properties. Even if this epoxy
stiffens after the oven test, it can never regain it's original properties.
I am allowing 24 hours room temp. cure + 4 hours at 100C whenever I can get
hold of a free oven in the lab. Will keep you posted.
regards,
Gussie
Augustus Fink-Nottle
In article <33cab045...@news.mcs.com>,
dyr...@mcs.com (Gary Dyrkacz) wrote:
>On the relationship between thinning and rigidity, I have always
>wondered what happens to the excess alcohol after the expoxy sets.
>Are epoxies porous enough so that the alcohol evaporates away, albeit
>slowly, or does it remain trapped in the polymeric matrix. If it does
>remain in thre it should affect the glass transition temperature and I
>guess that would definitely affect the rigidity, is that the
>definition of a plasticizer?
Yup. That's the plasticising effect. Epoxy doesn't need to be 'porous' for
these low moleucular weight constituents to leach out though. In time, they
will diffuse to the surface and escape, but some of it may remain trapped
forever after the diffusion process reaches equilibrium. In the case of
surface epoxy resins used with glass cloth, the fine weave of the cloth may
prevent the solvents from escaping at all, since the vapour pressure is
dependent on the pore radius! The finer the weave, the more dificult it'll
be for the solvents to come out.
You can accelerate this leaching process by subjecting it to elevated
temperatures, but we can't really put our planes into ovens now, can we? And
yes, it will depress the Tg (glass transition) making the epoxy more flexible
(ie. tougher), but the modulus will be lower as well.
The good part about this (solvent) method though is that now I know what to do
if I want to make a shock absorbing (but weaker than normal) epoxy joint!
pip-pip,
Gussie
gosc...@real3d.com
In article <33c66d29...@news.pacifier.com>,
NSS_gr...@pacifier.com wrote:
>
> In rec.models.rc.air,gosc...@real3d.com penned:
> >This leaves about 3 minutes to pply epoxy and wet out the joint.
>
> What does "wet out" mean?
>
> Is there a good way to get the best wet out?
>
What I mean by wet-out is basically what it sounds like. Get every part
of the joint wet with epoxy so when assembled, the epoxy will form a
solid surface to surface bond. The term is stolen from fiberglassing
jargon where wetting fiberglass means to impregnate the glass cloth with
resin but not to the point of saturation. Just enough to do the job. Wet
fiberglass becomes transparent much like wet ply will darken in color.
John
-------------------==== Posted via Deja News ====-----------------------
http://www.dejanews.com/ Search, Read, Post to Usenet
Chris Sorgatz
In article <5qe10f$jba$1...@hammer.msfc.nasa.gov>, fher...@hiwaay.net (Fred
Herrmann) writes:
> In article <5qdpb5$sb...@eccws1.dearborn.ford.com>,
> csor...@tc2941.pto.ford.com
> says...
> >I'm not even close to being a scientist, BUT, I do this
> >on the BIG BIRDS with gas engines (read: high vibration "mf'ers").
> Gee, I've never seen "mufflers" abbreviated this way. I also didn't know they
> vibrated. Also never heard of anyone doing "it" on a BIG BIRD either,
> especially one with a gas engine. Hope nobody from the Humane Society picks
> up on this post.. :-} Maybe all those stories Festa was telling me about
> those Ford employees are true?
>
> Fred V. Herrmann
>
> PS: The V. stands for Victorian
Ya know, I'm sittin here at work, trying to think up some retort, and I
can't!<grin> I'm absolutely speechless! <HFG> Fred, I think you've
shut me up............for the day.
PS- Yes, all those Ford stories ARE true, that is, if he was tellin you
about the fishin-waders and the sheep, inside of the new F150 trucks.
Christopher D. Sorgatz
PSS- NO! the D. does not stand for defeated.......<G>
Paul McIntosh
I checked the bottles of several brands of denatured alcohol and they
were all different as far as composition. This may be part of the
problem you had. Perhaps pouring the epoxy on a non-porous surface had
something to do with it, also. Try the same thing on a piece of wod.
As far as the epoxy not curing, I have not had that problem using either
lacquer thinner or acetone as a thinner for epoxy. Both act as a slight
inhibitor (up to twice the normal curing time) but the ultimate cure
seems just as strong and clean as the unthinned mixture.
BTW, I use 5 minute DHP thinned about 30% with acetone (in winter) or
lacquer thinner (summer) for laminating glass cloth. I get good
adhesion and sanding characteristics with both. I also use Z-poxy
finishing resin but it takes a lot longer to cure.
Edwin R Nickerson
Sorry for the double post but just had an after though.
If thinning epoxy, don't try to thin construction epoxy as compared to
finishing resins or laminating epoxies.
Must epoxies used for gluing have fillers added to them to thicken them up.
The alcohol is not always able to thin or dissolve the fillers and
problems may result. The finishing resins or laminating epoxies usually
donot have the fillers added and the alcohol usually doesnot have any
adverse reactions to them.
ed :-)
Edwin R Nickerson
If you let the epoxy set as a puddle, yes some of the alcohol will stay in
the epoxy and you will get rubbery epoxy as a result.
Remember, when using this to sheet a wing or for wetting out cloth, you
don't allow it to puddle. If the colth or sheeting feels wet, then you
have used too much. To truly test this method, try it in real life
situations.
The epoxy must be thin enough to allow the alcohol to evaporate off before
the epoxy sets up. It can';t do this if placed in a container and has
"thickness".
I have used thinned epoxy for some time without bad results. It does work.
ed :-)
all...@erols.com
If anyone is interested when alcohol is labeled as Denatured all it
means is that something has been added to make it undrinkable. Back in
my working days as a heat exchanger/pressure vessels engineer (need to
get back into that again) I used to travel to a lot of corn mash based
power alcohol plants producing anhydrous fuel grade (200 proof)
ethanol. One of the requirements that the BATF had was that each tank
car of product had to be denatured to prevent human comsumption. The
plants usually spiked each tank car with some gasoline. The stuff you
get at the drugstore usually uses some type of light hydrocarbon for the
same effect. Brian Allen
--
MZ?
Robert H. Klenke
Jeeze, talk about over analyzing a "problem!" People have been
using thinned epoxy to glass everything from models to real aircraft
and boats and it works fine. You said "the wing was nice and dry," but
the epoxy on the glass plate was "RUBBERY. It feels like SILICONE." Well,
you're going to fly the wing and not the glass plate right?!? It looks
like it will work fine like it always has for modelers throughout the
centuries. You're confusing the issue - finish the wing and go flying!
Bob
ps. In your "analysis" did you ever think that the balsa wing surface
helped wick some of the solvents out of the epoxy mixture? Put a dab
of alcohol on a balsa sheet next to a dab of unthinned epoxy. Which
one soaks into the balsa much faster?
--
-------------------------------------------------------------------------
Bob Klenke, Ph.D., Principal Scientist Dept. of Electrical Engineering
University of Virginia
http://csis.ee.virginia.edu/~rhk2j Charlottesville, VA 22903-2442
-------------------------------------------------------------------------
John...@dlux.net
In article <33c944c7...@news.mcs.com>,
dyr...@mcs.com (Gary Dyrkacz) wrote:
> >
> Although I am not an expert in any glues, its seems to me viscosity is
> not the only issue here. The ability of the epoxy to "wet" the wood
> is important. Even if the viscosity is low, you could have awful
> adhesion if the epoxy doesn't "wet" the wood. If the contact angle of
> the the two glues is about equal for wood, then viscosity would be the
> most critical parameter..
>
> -
> Gary Dyrkacz
> dyr...@mcs.net
> Learn about Radio Control Aircraft
> http://www.mcs.net/~dyrgcmn/
> -
Wetting the wood with epoxy is the key issue for the ultimate good bond.
You can heat the epoxy, you can add solvents (which ones?) and try other
methods to get the epoxy into the wood. Tricky work.
Here's a suggestion for you to consider: There is now a clear penetrating
epoxy solvent available for sale on the net. It is a 50:50 mix of
wood-based epoxy resin and a solvent mixture containing
I-don't-know-what. Mixed it has about the consistency of diesel fuel and
a potlife of 1++ hours depending on the temperature. The solvents carry
the epoxy into the wood and then evaporate out, leaving the epoxy
embedded in and around the wood fibers. This stuff has been around since
the 80's but has had poor distribution. I do know that it is used by the
State of CA for wood preservation.
The penetrating epoxy is itself not a bonding agent, but it does form the
basis for the subsequent addition of an epoxy glue or resin. If the glue
or resin is a true high-grade epoxy, the bonding is molecular and the
joint is secure. We have tested it in the boating business and found that
ANY high grade epoxy product-- resin, glue or filler -- will bond
securely with the base coat. If you're interested check it out @
http://www.rotdoctor.com/
Mike Wizynajtys
Fred Herrmann wrote:
>
> Seeing as I've got to pay off my wifes credit cards first, before I get the
> truck, the least I can do is admire a calendar of it. At least she said the
> "only" things she bought with the cards were things for the kids. Now where
> have we heard that one before?
>
Hi Fred,
I couldn't resist puttin my .02 in here.
You deffinitely have to find a way to get one of those new Fords. I just
got an F250 XLT Super Cab a couple months ago, and I love it dearly! I
switched from GMC and I may never go back.
Mike Wiz
Max Feil
Robert H. Klenke (rh...@hal.ee.virginia.edu) writes:
> you're going to fly the wing and not the glass plate right?!? It looks
Note that the wing was finished without thinning the epoxy.
I found the article interesting since epoxy, even when thinned,
is supposed to cure properly inside and out. That is one of the
great things about epoxy - it does not need exposure to air
to "dry" so it does not dry from the outside in like other glues.
When I thin epoxy, I never use anything containing water or other
junk. Use a pure volatile solvent like methanol or acetone and
thinning will work better. The thinned epoxy left over in my
mixing cup always ends up nice and hard, even though it does
take longer to cure.
Max
--
Max Feil
ah...@freenet.carleton.ca
Ottawa, Canada.
R Davies
This rubbery epoxy might be useful for joints between wings and fus or
mounting fuel tanks or something. Have you patented it yet??
Rob D
Gordon McConnell
Fred Herrmann wrote:
> >
> > Seeing as I've got to pay off my wifes credit cards first, before I get the
> > truck, the least I can do is admire a calendar of it. At least she said the
> > "only" things she bought with the cards were things for the kids. Now where
> > have we heard that one before?
> >
>
Fred,
Maybe you should get your wife one of those "Ford Citibank" credit
cards !! That way, when she's spending money she's earning you a
discount on your next truck...
I tried that, and had about a $2000 discount for my next Ford Van, but
ended up buying a Chevy anyway, as it was STILL $5000 cheaper... oh
well, its the thought that counts !
Jim Surra
I'm curious to see what happens after a few days of extended drying
time. I seldom bake my planes, but I'm curious about that test too.
JIM
Jim Surra
> were all different as far as composition. This may be part of the
> problem you had. Perhaps pouring the epoxy on a non-porous surface had
> something to do with it, also. Try the same thing on a piece of wod.
>
> As far as the epoxy not curing, I have not had that problem using either
> lacquer thinner or acetone as a thinner for epoxy. Both act as a slight
> inhibitor (up to twice the normal curing time) but the ultimate cure
> seems just as strong and clean as the unthinned mixture.
>
> BTW, I use 5 minute DHP thinned about 30% with acetone (in winter) or
> lacquer thinner (summer) for laminating glass cloth. I get good
> adhesion and sanding characteristics with both. I also use Z-poxy
> finishing resin but it takes a lot longer to cure.
>
> Paul
> www.dancris.com/~warbird
I've had the same results myself, and like you, always worked on wood.
Obviously, I usea different brand, but mine hardened fine. I'll have to
do a test with a non-porous surface. One thing, though, I'd think twice
before thinning epoxy with acetone. It's very agressive, not only to
the epoxy ingredients, but it'll kill a foam wing dead before you can
say "Oh, Sh__t! I killed my foam wing!"
JIM
Jim Surra
Robert H. Klenke wrote:
>
> In article <5qg1ql$ljl$1...@msunews.cl.msu.edu>, bhur...@pilot.msu.edu (Augustus Fink-Nottle) writes:
> using thinned epoxy to glass everything from models to real aircraft
> and boats and it works fine. You said "the wing was nice and dry," but
> you're going to fly the wing and not the glass plate right?!? It looks
> centuries. You're confusing the issue - finish the wing and go flying!
>
> Bob
> ps. In your "analysis" did you ever think that the balsa wing surface
> helped wick some of the solvents out of the epoxy mixture? Put a dab
> of alcohol on a balsa sheet next to a dab of unthinned epoxy. Which
> one soaks into the balsa much faster?
> --
> -------------------------------------------------------------------------
> Bob Klenke, Ph.D., Principal Scientist Dept. of Electrical Engineering
> University of Virginia
> http://csis.ee.virginia.edu/~rhk2j Charlottesville, VA 22903-2442
> -------------------------------------------------------------------------
Wait a minute! Flying a plate! I have an idea....... Boy, will this
one tick my wife off!
JIM
J.Davis
Depending on the brand there may be more or less diffrences.I personally
recomend a high quality product like Devcon or Hobby Poxy rather than
saving a little on bargain brands.One diffrence is the amount of soaking in
the epoxy does the longer setting time the more time it has to penetrate
giving more strength and a slower setting epoxy can be heated to reduce
it's viscosity for even more penetration or a smoother surface ( this can
be tricky) where this may be difficult with a shorter setting epoxy due to
an acceleration of the setting when heat is applied . It's my opinion that
you should use something in the 30 min range unless quicker is really
needed.
DBZS
I was under the impression that the "extra stuff" in denatured alcohol was
to prevent people from trying to drink it. Maybe if you tried pure ethyl
alcohol (everclear). You would get a more favorable result?
Jon-David Horne
You mean you're NOT supposed to drink that stuff?? hmmmmmmmmmm hehe