what to use instead of epoxy?
09-06-2011 | 05:35 PM
#1
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From: Ashland, WI
what to use instead of epoxy?
Has anyone used something other than epoxy for stabs, wing hold down blocks, firewalls and other high stress areas? If so what are you using..?
09-06-2011 | 08:47 PM
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From: PerthWA, AUSTRALIA
RE: what to use instead of epoxy?
That is very much the key - A proper design where glue in tension is not what is relied upon for the joint.
Provided the joint fits properly -
If the joint is under compression, the glue used is not all that important
If it is under shear - also not all that important
If it is under tension and relying upon the glue to hold it in place, Epoxy is the strongest choice.
If the glue itself is stronger than the wood it is bonding (IE - if the joint breaks and the glue stays in place but the wood on either side of the joint breaks), then the glue is strong enough. This also needs to take into account the longevity of the glue from such factors as fuel dissolving it and vibration fatiguing the glue (happens with CA).
Provided the joint fits properly -
If the joint is under compression, the glue used is not all that important
If it is under shear - also not all that important
If it is under tension and relying upon the glue to hold it in place, Epoxy is the strongest choice.
If the glue itself is stronger than the wood it is bonding (IE - if the joint breaks and the glue stays in place but the wood on either side of the joint breaks), then the glue is strong enough. This also needs to take into account the longevity of the glue from such factors as fuel dissolving it and vibration fatiguing the glue (happens with CA).
09-07-2011 | 03:43 AM
#5
RE: what to use instead of epoxy?
ORIGINAL: aussiesteve
That is very much the key - A proper design where glue in tension is not what is relied upon for the joint.
Provided the joint fits properly -
If the joint is under compression, the glue used is not all that important
If it is under shear - also not all that important
If it is under tension and relying upon the glue to hold it in place, Epoxy is the strongest choice.
If the glue itself is stronger than the wood it is bonding (IE - if the joint breaks and the glue stays in place but the wood on either side of the joint breaks), then the glue is strong enough. This also needs to take into account the longevity of the glue from such factors as fuel dissolving it and vibration fatiguing the glue (happens with CA).
That is very much the key - A proper design where glue in tension is not what is relied upon for the joint.
Provided the joint fits properly -
If the joint is under compression, the glue used is not all that important
If it is under shear - also not all that important
If it is under tension and relying upon the glue to hold it in place, Epoxy is the strongest choice.
If the glue itself is stronger than the wood it is bonding (IE - if the joint breaks and the glue stays in place but the wood on either side of the joint breaks), then the glue is strong enough. This also needs to take into account the longevity of the glue from such factors as fuel dissolving it and vibration fatiguing the glue (happens with CA).
Bob
09-07-2011 | 09:13 AM
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From: Avilla , IN
RE: what to use instead of epoxy?
ORIGINAL: Avaiojet
There's nothing wrong with using Epoxy, for the areas you mentioned.
What do you have against Epoxy, to be used as a glue?
Charles
There's nothing wrong with using Epoxy, for the areas you mentioned.
What do you have against Epoxy, to be used as a glue?
Charles
09-07-2011 | 03:06 PM
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From: PerthWA, AUSTRALIA
RE: what to use instead of epoxy?
ORIGINAL: sensei
LOL, Are you kidding? If you have glue line failures, then the overall design is just poor, not the CA...
Bob
ORIGINAL: aussiesteve
That is very much the key - A proper design where glue in tension is not what is relied upon for the joint.
Provided the joint fits properly -
If the joint is under compression, the glue used is not all that important
If it is under shear - also not all that important
If it is under tension and relying upon the glue to hold it in place, Epoxy is the strongest choice.
If the glue itself is stronger than the wood it is bonding (IE - if the joint breaks and the glue stays in place but the wood on either side of the joint breaks), then the glue is strong enough. This also needs to take into account the longevity of the glue from such factors as fuel dissolving it and vibration fatiguing the glue (happens with CA).
That is very much the key - A proper design where glue in tension is not what is relied upon for the joint.
Provided the joint fits properly -
If the joint is under compression, the glue used is not all that important
If it is under shear - also not all that important
If it is under tension and relying upon the glue to hold it in place, Epoxy is the strongest choice.
If the glue itself is stronger than the wood it is bonding (IE - if the joint breaks and the glue stays in place but the wood on either side of the joint breaks), then the glue is strong enough. This also needs to take into account the longevity of the glue from such factors as fuel dissolving it and vibration fatiguing the glue (happens with CA).
Bob
When I use epoxy, I use Aeropoxy quite a bit these days (with the mixer and applicator gun) but still spend most of my effort making sure the joint is right (and the right sort) to start with.
09-07-2011 | 05:47 PM
#10
RE: what to use instead of epoxy?
If you goto the thread "is anyone using weldbond glue?" in this forum, post 42, there is a few pics of my airplanes completely constructed from CA and Gorilla glue for the sheeted parts, including the motor boxes and they are all gassers. I have nothing against epoxy, besides weight, in fact; I have made my living with it for the last 40 years.
Bob
Bob
09-07-2011 | 07:30 PM
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From: Tunica, MS & Huntsville, AL AL
RE: what to use instead of epoxy?
I use 'em all but thin CA works best with Gorilla Glue or epoxy over the top next after the CA dries, wetting the wood a bit helps gorilla glue adhere, on some harder, denser woods it doesn't soak in but just hardens on top giveing the "appeareance" of a glued joint
09-08-2011 | 03:54 AM
#12
RE: what to use instead of epoxy?
This is my scratch built 52% Extra 300 SP that weighs 48.5 lbs. with a DA 200cc, it has a 150" wing span and a 144" fuse length. It is completely constructed using CA on all wood parts and Gorilla glue for sheeting on foam parts only. This is a video that a guy was doing at a big bird event a couple of months ago.
http://icanflyrc.com/Tricityflyers/B...Bird2011A.html
http://icanflyrc.com/Tricityflyers/B...Bird2011A.html
09-08-2011 | 02:48 PM
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From: PerthWA, AUSTRALIA
RE: what to use instead of epoxy?
VERY nice work sensei. It is exactly what I was referring to - the proper joint type and fit. I don't see much adhesive under tension there
I understand that yours are your designs but unfortunately, there are many kits out there that don't necessarily have as much thought put into the joint types.
I "Dabbled" in a business for a few years where about 50% of the business was the manufacture of various resin compounds including Adhesives ranging from PVA's through Acrylates to Epoxies and Urethanes
I understand that yours are your designs but unfortunately, there are many kits out there that don't necessarily have as much thought put into the joint types.
I "Dabbled" in a business for a few years where about 50% of the business was the manufacture of various resin compounds including Adhesives ranging from PVA's through Acrylates to Epoxies and Urethanes
09-08-2011 | 07:05 PM
#14
RE: what to use instead of epoxy?
Thanks for the kind words. You are right on the money, construction and joint design along with joint fit is all key to a strong and light airframe.
Bob
Bob
09-10-2011 | 01:33 PM
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From: Stone Ridge,
NY
RE: what to use instead of epoxy?
First of all, you really can't make a simplistic remark like "What do you use instead of epoxy?" without first determining the materials being used in the construction. Let's face it, you wouldn't use latex house paint to paint a full size F-18 Hornet now would you?
Epoxies are very strong and resist most chemicals once cured, which is why they are used frequently in high stress areas. They are usually strong in both shear and tension. In most applications where a glue is needed, you don't really think about compression (remember I said most cases). The different formulations will alter the properties, as you can easily see by the typical brittleness of 5-minute epoxy compared to something like 30-minute epoxy which yields a more resilient bond. Epoxies have great gap filling properties and can be thickened by adding things like glass fibers, cabosil or microspheres if weight is an issue.
CA's on the other hand have great strength in the tension direction but contrary to what was mentioned earlier, not as good a strength in the shear direction. Again, there are different formulations for different applications.
Then there are the urethane based glues like Gorilla glue and such and the aliphatic types like Tite-Bond and Elmer's Carpenter glue and the rubbery type glues like Goop and Shoo-Goo and last but not least the vinyl based glues that stay flexible like RC-56. Each one has their place in the building of R/C planes.
If you are going to be building smaller to mid-size electric planes, vibrations are not too high on the worry list so just about any glue would have a stronger than the material strength joint given a reasonably sufficient mechanical joint. CA's are the preferred glue of choice since they cure quickly and contribute very little weight to the project if used judiciously.
When you jump up to the larger models, you're going to want something that gives a little more strength and durability so epoxies will figure in there.
What I'm trying to say is you have to use the proper glue just like you should use the proper tools when building. The best advice is to ensure your mechanical joints are good and then, based on the materials being joined, select your adhesive appropriately.
Epoxies are very strong and resist most chemicals once cured, which is why they are used frequently in high stress areas. They are usually strong in both shear and tension. In most applications where a glue is needed, you don't really think about compression (remember I said most cases). The different formulations will alter the properties, as you can easily see by the typical brittleness of 5-minute epoxy compared to something like 30-minute epoxy which yields a more resilient bond. Epoxies have great gap filling properties and can be thickened by adding things like glass fibers, cabosil or microspheres if weight is an issue.
CA's on the other hand have great strength in the tension direction but contrary to what was mentioned earlier, not as good a strength in the shear direction. Again, there are different formulations for different applications.
Then there are the urethane based glues like Gorilla glue and such and the aliphatic types like Tite-Bond and Elmer's Carpenter glue and the rubbery type glues like Goop and Shoo-Goo and last but not least the vinyl based glues that stay flexible like RC-56. Each one has their place in the building of R/C planes.
If you are going to be building smaller to mid-size electric planes, vibrations are not too high on the worry list so just about any glue would have a stronger than the material strength joint given a reasonably sufficient mechanical joint. CA's are the preferred glue of choice since they cure quickly and contribute very little weight to the project if used judiciously.
When you jump up to the larger models, you're going to want something that gives a little more strength and durability so epoxies will figure in there.
What I'm trying to say is you have to use the proper glue just like you should use the proper tools when building. The best advice is to ensure your mechanical joints are good and then, based on the materials being joined, select your adhesive appropriately.
09-10-2011 | 04:34 PM
#16
RE: what to use instead of epoxy?
ORIGINAL: John Sohm
First of all, you really can't make a simplistic remark like ''What do you use instead of epoxy?'' without first determining the materials being used in the construction. Let's face it, you wouldn't use latex house paint to paint a full size F-18 Hornet now would you?
Epoxies are very strong and resist most chemicals once cured, which is why they are used frequently in high stress areas. They are usually strong in both shear and tension. In most applications where a glue is needed, you don't really think about compression (remember I said most cases). The different formulations will alter the properties, as you can easily see by the typical brittleness of 5-minute epoxy compared to something like 30-minute epoxy which yields a more resilient bond. Epoxies have great gap filling properties and can be thickened by adding things like glass fibers, cabosil or microspheres if weight is an issue.
CA's on the other hand have great strength in the tension direction but contrary to what was mentioned earlier, not as good a strength in the shear direction. Again, there are different formulations for different applications.
Then there are the urethane based glues like Gorilla glue and such and the aliphatic types like Tite-Bond and Elmer's Carpenter glue and the rubbery type glues like Goop and Shoo-Goo and last but not least the vinyl based glues that stay flexible like RC-56. Each one has their place in the building of R/C planes.
If you are going to be building smaller to mid-size electric planes, vibrations are not too high on the worry list so just about any glue would have a stronger than the material strength joint given a reasonably sufficient mechanical joint. CA's are the preferred glue of choice since they cure quickly and contribute very little weight to the project if used judiciously.
When you jump up to the larger models, you're going to want something that gives a little more strength and durability so epoxies will figure in there.
What I'm trying to say is you have to use the proper glue just like you should use the proper tools when building. The best advice is to ensure your mechanical joints are good and then, based on the materials being joined, select your adhesive appropriately.
First of all, you really can't make a simplistic remark like ''What do you use instead of epoxy?'' without first determining the materials being used in the construction. Let's face it, you wouldn't use latex house paint to paint a full size F-18 Hornet now would you?
Epoxies are very strong and resist most chemicals once cured, which is why they are used frequently in high stress areas. They are usually strong in both shear and tension. In most applications where a glue is needed, you don't really think about compression (remember I said most cases). The different formulations will alter the properties, as you can easily see by the typical brittleness of 5-minute epoxy compared to something like 30-minute epoxy which yields a more resilient bond. Epoxies have great gap filling properties and can be thickened by adding things like glass fibers, cabosil or microspheres if weight is an issue.
CA's on the other hand have great strength in the tension direction but contrary to what was mentioned earlier, not as good a strength in the shear direction. Again, there are different formulations for different applications.
Then there are the urethane based glues like Gorilla glue and such and the aliphatic types like Tite-Bond and Elmer's Carpenter glue and the rubbery type glues like Goop and Shoo-Goo and last but not least the vinyl based glues that stay flexible like RC-56. Each one has their place in the building of R/C planes.
If you are going to be building smaller to mid-size electric planes, vibrations are not too high on the worry list so just about any glue would have a stronger than the material strength joint given a reasonably sufficient mechanical joint. CA's are the preferred glue of choice since they cure quickly and contribute very little weight to the project if used judiciously.
When you jump up to the larger models, you're going to want something that gives a little more strength and durability so epoxies will figure in there.
What I'm trying to say is you have to use the proper glue just like you should use the proper tools when building. The best advice is to ensure your mechanical joints are good and then, based on the materials being joined, select your adhesive appropriately.
09-10-2011 | 04:51 PM
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From: Birmingham, AL
RE: what to use instead of epoxy?
I have a Kadet Senior built with Titebond that is still doing fine with all joints intact after 25+ years.
These glues are good. I do use epoxy for heavy duty apps like firewalls and LGs and sometimes CA for tacking.
And white glues taste better when you chew them off your fingers. Sorry but never got over 1st grade. That glue was tasty!
Tom
These glues are good. I do use epoxy for heavy duty apps like firewalls and LGs and sometimes CA for tacking.
And white glues taste better when you chew them off your fingers. Sorry but never got over 1st grade. That glue was tasty!
Tom
