Lonestarxp

ok, do i REALLY need to use 30 min epoxy when the kit calls for it? or will 6 min be fine? i know 30 min has a stronger bond.. but is it MUCH difference?

hawkco66

In a nutshell...30min is fuel proof. 5 min is not.

For the long story...wing halves, tank areas, firewalls, etc...get 30min. Doesn't mean you can't use 5 min in a pinch buuutttt....30 min is fuel proof.

Also, for tail feathers, 30 min gives much more time to adjust with tape measure before it sets. By the time you mix enough 5 min epoxy for a large area, fill the area, place the pieces together, the glue will be setting. 5 min works fine for things like servo blocks, some hinge configurations (not CA hinges), some gear blocks, and other misc stuff.

I personally use 30 min for the big stuff and usually either thin or thick CA for everything else.

hawk

DGrant

My Feedback: (4)

The only diff in the fast-cure and slower-cure is the curing time. Each one is essentially the same, as in fuel-proof.
As was said though, the difference in working time is a definate benefit for most. The slower curing epoxies allow for "less stressful" building.
Also, my experience is that the 30minute varieties end up with a stronger joint/bond. The extra time allows the resin to permiate the wood, and seep into places that 5minute wouldn't go, because it dries before it gets there.

Lonestarxp

thank you very much.. im gonna get some 15 min instead.. 30 min is just too darn long

Fastsky

15 minute epoxy is a good all around choice. Not too fast and not too slow. I found that 30 minute epoxy usually takes more like 45 minutes to an hour to cure. LIke you said, thats a long tiome to wait!

rc-sport

My Feedback: (12)

I was always told that a 30 min epoxy should be used when you need a real strong bond because the slower cure time allows the epoxy to penetrate the wood fibers better. As far as fuelproof, they're all the same.

MinnFlyer

My Feedback: (4)

Something else to consider in curing time is temperature. Warmer temps will help epoxy cure faster. I often put my epoxy in the microwave (It only takes about 15 seconds, don't over-do it!) to warm it up either before or after mixing (also be care of the fact that this thins out the epoxy. Don't be surprised if the thick part comes out of the bottle like water). another trick is to heat up the wood with your heat gun after the joint is epoxied.

TRP

My Feedback: (1)

Since we are talking about epoxy...

I thinned down some 30 minute epoxy with denatured alc. so it would 'flow' into the corners of my fuel tank area better. Did this thinning process weaken the bond of the epoxy?

thx!
TRP

f2racer

Who in the world told you this? Any 2 part epoxy should be fuel proof...

MinnFlyer

My Feedback: (4)

No. Thinning epoxy is a standard way of making it flow, especially for fuel-proofing engine and tank compartments. Your joint will not be as strong as if you had NOT thinned it, but only because there is less epoxy on the joint. After it's thinned, the Alcohol evaporates, and the epoxy hardens as usual.

(Note to newbies: This is an EXCELLENT way to fuel-proof your engine and tank compartments)

latch66

OK, I'm obvioulsy the odd ball.

I use the 45 minute epoxy on all surfaces wich will receive a great deal of stress, wing halves, horizontal stabs, and verticle stabs. The reason is increased strength. If you are ever able to look at the balsa to balsa joint you will see how much the slower setting epoxy has soaked into the balsa, creating a stronger bond.
I will use 30 minute epoxy if necessary.

I like using the 5 minute epoxy for small jobs, or to fuel proof with alcohol.

Is this necessary, maybe not, but its the way I build. I hate losing an airplane to structural failure. My own dumb thumbs I can deal with a lot better. But to loose one because I took a shorcut on building is a different matter.

One other thing to note about epoxy. Some 30 minute epoxy's will dry in much less time if large batch made. I ran into this problem on the second airplane I built and almost didn't get the wing halves together before the epoxy set. It set in about 10 minutes (you had to trap 4 plywood ribs and the spar between each wing half).

Build to your own satisfaction. Your the person flying the airplane. Just keep in mind, no airplane flys well with part of its lifting structure missing (wing, horizontal stab, verticle stab).

Ronaldcorb

Another "trick" is to do what I do. Build in your garage in Las Vegas in the summer with 100 + temp.! I mixed a batch of 5 Min that had been sitting on the bench all day and when it started to cure it also started to SMOKE

Now I keep my epoxy in the fridge untill a few minutes before I need it. Just let it sit out a little longer if I need a thinner epoxy.

Ronaldcorb

latch66

We can't build in our garages around here. The mosquitoes will eat you alive (too many rice fields nearby). I tried it when we first moved here. Gave up after two attempts (Yes, it did take twice for me to learn). Now I build on the dining room table. Gives my wife something to complain about.

When I am using the thinned epoxy (fuel proofing, reinforcing the firewall), I will also use my heat gun to get the epoxy to "flow" much better. Works for me.

Mike James

We could talk about epoxy forever... so many brands and types. And each has it's own properties that are easily read about. Some companies even give you facts about the strength, etc..

But that's not as important as building a strong structure. I think anyone out there who is considered a "master builder" will tell you that the most important quality you can have in this hobby is a little patience. You'll have safer aircraft, and probably neater-looking ones too.

Why is 30 minutes too long too wait, for a better structure? Go build a different part of the plane, read ahead in the instructions, sand something, or whatever, during this time. When you're in a big hurry, you're bound to screw something up. Just relax, and give some more thought to quality. You won't be sorry.

GrnBrt

My Feedback: (5)

Mikejames0 hit the nail right on the head!!!! If waiting for 30 minute epoxy to set up is to much for your patience then you are in the wrong hobby. I have nothing faster then 30 minute in my shop and while that is setting up there is always something else that can be done. Be glad we have the epoxies and you don't have to wait for white glue to set up like I had to way back when as that really took some time. slow down and enjoy the building process.

TIGER2PLANE

I use 15 min as a rule but I have my son inlaw to help. here is some thing you can do to pass the time, get a VCR and have your wife or someone else take movies and when your waiting just watch them for a while and the next thing you know you are ready to move on to something else/////

khodges

My Feedback: (1)

When I use epoxy, I generally use 5 and 10 minute varieties. If I want a really fast bond, I use CA, if I'm willing to wait, I use wood glue, unless it's for a firewall or high stress area like a wing center section or landing gear plate, when I always use epoxy. I use all three when I build, and I guess I'm a bit old fashioned because I like wood glue a lot and use it the most in a build. You can move parts a bit to align them, there's plenty of working time, it is somewhat flexible when fully cured, and is also lightweight when cured. Once you clamp a piece, it will be set well enough to handle in 45 minutes, although full cure is about 24 hours. I've never been in a big enough hurry to build something that I can't wait 45 minutes.
When using relatively quick-setting epoxy, I have all my clamps ready, and "rehearse" the application and fitting so I don't waste time once I mix. I also usually add microballoons and/or milled fiberglass to my epoxy, to lighten or strengthen it. FWIW, Loctite makes a good epoxy, you don't need to pay the extra for "hobby grade" epoxies. I build in my garage, which is unheated. Summertime I have a window AC, and winter I have small space heaters, and I'll park the epoxy bottles in the warm air stream to keep them flowing, but I don't get them warm to the touch, because it will shorten the set time.