Does the strength of epoxy generally increase with set time? Is 60 minute epoxy going to be stronger that 30 minute? Im pretty sure there is a difference between the 5min and 30min stuff but is there a benefit to getting even slower setting epoxy as far as strength is concerned?

Khlash99

Yes, slower setting poxy tends to be stronger and tends to "sink in" to the wood/balsa better, plus it gives you more work time. Ever notice how 5 minute epoxy gets kinda stringy after a minute or so?

For joining wings and tail surfaces, I recomend that you use a slower epoxy (like 30 minute) so you have time to check, recheck and check again that the pieces are together straight and proper.

Happy building.

I doubt the actual strength of the epoxy matters. But what does matter is its bond to the wood. 30 min has much more time to soak in and create a better bond to the wood, and therefore, more strength. The likelihood of epoxy breaking before the wood its glued to is very small, but it can let go so we need the penetrating action of slower cure epoxy.

I use 30 minute epoxy when joining wings......and fibeglassing the center section. I have found that heating up the epoxy with a heat gun/hairdryer thins it allowing better penetration..I use five minute on everthing else...servo trays....pushrod tubes. I find myself using epoxy on most things now.. it definitely shows when you crash tooo.......the epoxy joints are the only thing the survive. lol

99,

I also repair golf clubs and use overnight epoxy on them. I have experimented and found no noticeable need for anything over 30 minute epoxy for RC building. that seems to be the break point. if you use 60 or longer epoxy you really can't do anything until the next day. And as said above, I have had some crashes were the 30 minute epoxy bond was the only thing not broken.

I always poke small holes with the tip of an x-acto blade in the two pieces before applying the epoxy so they penetrate the wood a little more.

I use 2-hour epoxy to install wing dihedral brace and joining wing halves. The super slow epoxy penetrates the wood before the epoxy is fully set. I also let the epoxy fully cure for a couple of days.