Hey guys,
I got a world models extra 300, my first ARF to build, since then I have had many ARF's and assembled them right. I used epoxy on the CA hinges for rudder, elevator, and ailerons. It holds great and I have smooth joints( they all move freely) Just wondering if it is ok to fly like that, or if there are any ideas on how I can get it off if necessary, without replacing the airplane! [sm=disappointed.gif]
-Mike

If it was my plane I would just cut the surfaces free from the the wing/fuse. Then reslot for new CA hinges next to the old hinges and reinstall. Best of luck!



HTH

If you've done similar hinging with CA then you have something to compare your epoxied ones to.

If both techniques allowed surface movement with about the same lack of resistance to the movement, then there is little reason to worry. I'd leave the epoxied hinges alone.

CA hinges are three layers. The outer two layers are there to wick the CA into the hinge area within the slots. The middle layer is to provide strength to the hinge. If the epoxy coating extends all the way to the back of the hinge it'll probably hold as strong as the CA could hold. If it's not stiffened the flex of the hinged surface, no harm, no foul.

It ought to be easy for you to feel how stiff the epoxy hinges are and how stiff your CA'd hinges are. While you're doing that, pull each and every hinge. Pull with enough force that you are worried you might pull out a weak hinge, which is exactly what you want to do. But don't pull so hard you break any balsa. That's the test every CA hinge ought to get anyway. And it's a perfect one to use to see if the epoxied ones are good.

Your post suggests that you've already checked the strength and "looseness", so..... Noting about epoxy would be bad for that application. It isn't a perfect glue for the "naked" nylon hinges that used to be so popular before CA hinges came along, but that's the fault of the nylon not the epoxy. With the outer layers of CA hinges being "grippy" that problem wouldn't exist.

BTW, epoxy actually does an excellent job holding nylon, but you've got to drill holes (you'll notice that the nylon hinges all come with a lot of holes already in the flats) through the mating surfaces so that the epoxy will bridge through the holes and create epoxy "nails". And when that's done, ain't nothin' gonna be stronger.

wow that is a new one keep us posted if it works. i still will not use it but just wandering

It should be OK, but for added insurance, "pin" the hinges in place. Drill a 1/16" hole through each side of each hinge, from the top of the wing (stab, fin) and aileron (elevator, rudder) through the bottom. Then push a common round toothpick through each hole, trim the toothpicks flush with the top and bottom surfaces and put a drop of thin CA on each end of the toothpick.

Jim

I will give em a good tug before each flight, and try that toothpick deal :-)
Thanks,
Mike

The pinning of hinges with toothpicks as described by jrf is a good idea that has been used on nylon hinges for decades. Today many ARF's are crashed long before their owners learn that hinge slots can wear out on high mileage planes.
So, for them it's a non-problem.