ORIGINAL: bigtim
ORIGINAL: RCKen
If I read correctly you have a plane that has the wing already joined and 5-minute epoxy was used to jointhe wing. If this is the case then you will be just fine with it. While it's not how I would have built the plane (I would use 30+ minute epoxy), but the wing is more than likely going to be just fine the way is. And I can assure you it's not going to be worth the hassle of trying to cut the wing apart to re-do it with 30 minute epoxy. If the wing is already joined the give it a good tug to ensure that it's well bonded and then fly it.
Now if the wing halves haven't been joined yet, then yes you want to use 30+ minute epoxy to join them with.
Ken
other than working time, why would you recomend 30 min epoxy for wing joining,relative strength is vurtually the same for both epoxies, as much as there is alot of myth making on RCU about penetration and strength etc.. its just not true.
cured epoxy is cured, wheather or not its the quick hardening or long, the amount of strength difference is negligible, and would make no difference in models of the size generally flown, including giant scale planes.
that being said of course I would use 30 min epoxy for joining wings or any area where minor adjustment might be necessary,but saying its because its stronger is not correct in so much that it would make no real difference the wood in a wing joint would fail before the adhesive did.
This is actually not entirely true. Epoxy gets its strength from polymer chains formed when the epoxy cures. With longer setting epoxy the polymer chains have more time to form longer chains.So the 30+ minute epoxy can form strong chains in the structure of the epoxy and does make it stronger. Yes, in many cases it is as you say that the wood is stronger than the epoxy. But saying that 30 minute epoxy isn't any stronger than the 5 minute epoxy isn't entirely correct. Also it does have more time to penetrate the material it is bonding as well.
Ken