HI,

I heard some drill a hole to help ca flow. Good idea?

Definately. I drill the hole first and then slot using that as a guide. It doesn't take much of one to wick the CA all the way out the back in one "pour", which is what you want. CA hinge material is only virgin once and an application after the first is too late.

I just finished assembling a Tower Hobbies Kaos 40 ARF.

The instructions said to do just that - drill a small hole mid point of the hinge slot to aid in "wicking" the thin CA.

It seems to work well although I managed to make a mess of it getting too much CA where it was not needed.

Oh, well, maybe by the time I do about 100 kits/ARFs I'll get it right.........

Dave

Yes, an excellent idea. I believe MinnFlyer has a sticky post somewhere about CA hinges. Good idea to read through, if you're just getting used to them.

Best wishes,
Dave Olson

i have always center drilled my ca hinges even if you cant get your covering trimmed back enough the center hole in the hinge slot lets you get the ca where you want it. i used the small ca tip tubes for the first time,and wondered why i never used them before.man those things are neat they saved me about a third of a bottle of ca on a build i just finished.they worked great for doing the ca hinges,i usually have to hold a towel soaked in acetone behind them, with the ca cap tubes i managed to actually get 4 to 6 drops in the hinges and didn't spill one drop.

[link=http://www.rcuniverse.com/magazine/article_display.cfm?article_id=55]Minnflyer's CA Installation How-to[/link]

Yes, drill a hole in the center of the slot for CA to wick into.

Ken

No drilling necessary. I've never had an in-flight failure or problem using this technique:

CA Hinge Installation

There are several rules to follow for an easy, correct CA hinge installation. These rules are good for hinges from different manufacturers, including Great Planes and Radio South. I’ve used them on many planes from pylon racers to Unlimited class Fun Fly planes to even a giant scale Stinger (the 1/4 scale size hinges). I have never had an in-flight failure using this procedure.

I have seen only two in-flight hinge failures. One failure was from catastrophic flutter, which also destroyed the wing panel. The other was due to doubled hinges and the use of thick CA.

Here we go:

Use a #11 blade to cut the slots.
Cut only once per side/per hinge.
Use only thin CA.
Do not double the hinges.
Do not use “kicker�.
Install after covering.

1. Slot the wood pieces, install the hinges, and mount the control surface. Gently push the pieces together.
2. Flex the control surface both ways for the maximum amount of travel you expect to use. This will automatically create the proper hinge line gap.
3. Slowly drop 2-3 drops of CA on each hinge at the hinge line on one side only. If any CA puddles in the hinge line, blot it with a paper towel.
4. When that is dry, apply 2-3 drops of CA to the other side of each hinge.
5. When both sides are dry, flex the control surface both ways.

That’s it! The wood will pull out before the hinge will let go. The surface will tend to stay centered and will not flop around. Both will help prevent flutter.

Dr.1

Long Answer:

I have done both ways and both have failed in-flight, although no crashes resulted. On my Mayhem, I lost Rudder, Elevator and one Aileron on separate occasions due to CA hinges tearing...not glue failure. On my Showtime, I have lost one elevator half and one aileron...same problem.

I now use only Robart hinges or pinned hinges and gorilla glue. You may be happier skipping the CA hinges all together and going with something more sturdy. CA hinges will probably be fine for now, but as you advance, you will put larger throws and higher stress on your hinges. Eventually, you will need to know how to install real hinges, so why not learn now?

CA hinges are just not strong enough for some planes and some types of flying/loads. (Keep in mind that the planes in which the hinges failed had over 45 degrees of throw on all surfaces. That's just too much for CA hinges over time.) I never had a problem with them until I started learning 3D. They will be fine in any trainer or sport plane.


Short answer:

Drill the holes

There are different quality CA hinges. After you've seen a few brands, you notice that some seem thicker than others. Truth is, some look dowright thin.

We've had a number of CA hinge failures in the last year at our field. Everyone I had a chance to autopsy showed the same thing. Every one of the hinges that failed were thin ones (some didn't have the fuzzy laminations) and had simply ripped along the hinge line.

Not a one of the failures was a fault of the CA not holding the hinge flat in the balsa. This last year, there wasn't a single case of a CA hinge pulling out that the pulled out part wasn't completely covered by balsa that had been pulled out of the airplane. You can't blame gluing technique for that. There wasn't a single case of a hinge that showed only partial penetration of the CA.

It appears that ANY gluing technique works more than adequately.

What does need attention is the quality of the hinge.

Do I drill? nope. The idea is convenience. If I was going to go to the extra effort of drilling, I'd pass on the CA hinges and simply use Hinge Glue and Dubro hinges. Matter of fact, I do just that on my "extra nice" models because it takes very little extra time over CA hinging and is just as easy.

Man, I have been doing this since Christ was a kid and I have never heard that. I wish you would have said it years ago. Great idea! I always drill the hole, but never first. That would be so much better. The slot first and the hole next isn't bad, but this would give you a way nicer job. Thanks.

In the "CA Hinge Installation How-To" that I wrote, I tell people to drill the hole. Personally, I don't ALWAYS do it, but then, I have enough experience to know when I can get away with NOT doing it.

For anyone who is not VERY familliar with the different types/grades/grains of balsa, it is always a good idea to drill the hole to be SURE that you get a good wicking of the CA

But the hole is only ONE step in insuring that the hinges are installed correctly. I recommend that everyone read it - even if you've installed CA Hinges dozens of times - there is some great information in there

As most posters have said, drilling a hole is a good way to get the CA to wick up on the hinge and give you good bonding between the hinge and the balsa.

Some hinges come slotted, that is they have a slot that would sort of act as the drilled hole and allow wicking up into that slot.

No matter what method you choose, drilling or using slotted CA hinges, there are some points that you should remember:

1. Never NEVER apply CA twice on the same side. Drip 4 or so drops of CA on one side and let it set. Flip the surface (aileron, rudder, elevator.. whatever) over and do the same to the other side. DO NOT re-CA a hinge after you have already applied the CA. This will sort of de-bond the CA and will cause a failure. It happened to me on my Tiger 60. I ended up removing the ailerons and re-hinging it in different places, this time, following the instructions that my instructor gave me.

2. Pin the CA hinges in the center then pass the hinge in the slot up to the pin. Then slide the other side up to the pin. The pin will insure that the hinge goes in all the way. Pull out the pin when satisfied then apply the CA.

Good luck.