I have a new ARF to build and the hinges are CA type. I've never work with this. The manual explain to first install the hinge into one surface and add CA ( not mentioned but I guess thin CA is recommended ? ). Then, they instruct to install the second half of the hinge into the second control surface and add CA to it. To me this is a bit strange. I would have install the hinge to both surface and then add the CA to the hinge. This way you can slightly move the hinge to get a perfect fit. What is the best way of doing it ?

Thanks,
Séb

RCU member Minnflyer has done an excellant How-to on installing CA Hinges. It should answer all of your questions.

[link=http://www.rcuniverse.com/magazine/article_display.cfm?article_id=55]Installing CA Hinges[/link]

Ken

The best place for CA hinges is in the trash. I hate changing broken hinges and CA hinges, especially CA hinges that come with ARFs, break and hopefully only the hinge will need replaced. A CA hinge flexes. I've broken plastic and metal by flexing it repeatedly. Just my opinion.

Many people feel this way, however, I have planes that are well over 15 years old that still have the original CA hinges.

I have used CA hinges in more than 50 planes (Even large scale) and have NEVER had a failure yet.

Read the "How-To" I did (The one that Ken posted the link to)

It explains how to install them properly.

pumbadog, I agree and I thing we have another convert as of Sunday. One of the guys, a very experienced flyer, came out with a new Slow Poke. He almost never got it to the ground in one piece after some not to smooth move, when he came in for the landing, he couldn't keep it lined up with the runway, the plane was making 90 degree turns on him. Finally he got it close to the ground at 90 degrees to the runway and ended up hitting the brem at the fence. Three of the four aileron hinges had pulled out on the left wing. They were soaked with CA and hard as a rock, but not a scrap of balsa was to be seen on them.

I've seen this to many times. I've yet to see a pinned hinge fail unless the aileron was torn of in a crash, and then there was gobs of balsa still attached.

My bet is our guy was busy installing pined hinges when he got home.

Don

Couple of possibilities why you saw that.....

The hinge failed to hold the CA. Dubro hinges used to do that and they put holes though the flats so the glue would make "rivets" from the wood on one side to the wood on the other. Then the hinge could let go of the glue or not and would still hold thanks to the glue pinning the wing together through the holes. And back then, some of those type hinges were shiney. They didn't hold the glue worth spit from the gitgo. They're no longer sold. And Dubros now seem to be a plastic that doesn't continue to bleed solvent.

Lot's of CA hinges don't get rock hard when CA'd. Especially if you flex them during the installation. Technique is important doing any job.

All CA hinges are not equal. Just like all brands of anything aren't equal. We used to learn how to select balsa and reject the bad stuff. We also learned which flat hinges were going to let go of the epoxy (their plastic bled solvents that separated the epoxy from the plastic over time) and quit buying them.

Right now, I won't use a CA hinge that has no "fuzzy" on both sides. I also test all of the rest to see how well the fuzzy is attached. Never had a hinge fail since doing that. Also never ever had one that hardened. Flexing during installation might be the trick. You can do it before inserting, but should do it as the CA is setting up if only to keep the hinge supple.

The main point here is not a complaint about CA hinges because, like the old 'ford vs chevy' debate we've heard so many times, this is about technique. This is basic synopsis of Minnflyers instructions.

First of all, do NOT apply CA until the hinges are installed, with the proper hinge insertion depth (equal on each side), pinned through each surface to hold them in place, with the gap is properly set (of course, set the gap before pinning them in place).

Then bend the (I will use aileron as an example) aileron to max throw but not beyond, so you don't pull it out. Apply CA to all the top (or bottom) hinge sides first. Flex the hinged connection, meaning if you are doing ailerons, flex the aileron up and down a few times.

Then bend the aileron the opposite way exposing the other side that has not had CA applied, and apply the CA on all of the hinges on that side.

When done, remove the pins and flex the hinges again to make sure you have full movement. Full movement means that it will freely travel up an down within th manufacturer's throw limits.

DO NOT reapply CA once done. One application is good. Two applications can be disasterous. This does something to the bond and will cause it to fail in the future.

CGr

No kidding. I once purchased an airplane from a guy that did this. The hinges were very brittle and many broke clean in half. I rehinged the whole airplane after the first broke. I've never had a problem with any CA hinge that I've installed.

Close, but no cigar.

You do NOT pin the hinges in place.

IF the surface you're hinging (Let's say elevator to stab) is built-up, there is a chance that the hinge can go too far into one side or the other, so a pin in the CENTER will hold the alignment so it can't go too deep into the stab or the elevator.

Also worth noting is that if both surfaces are solid, and you didn't cut the slots ridiculously deep, the slots themselves will keep the hinges from going too deep and the pin is not necessary.

But please. read the "How-To" for the rest of the instructions. It's written in very clear, easy-to-understand wording with illustrations.

[link=http://www.rcuniverse.com/magazine/article_display.cfm?article_id=55]How To Install CA Hinges[/link]

Some ARF supplied CA hinges are wierd.lol
They don't have fiber like coating on them like the GP hinges...so I drill tooth picks
or pins into them after installation just to make sure.

I opt to use epoxy..becuase I'm too slow
Plus I don't like gaps, and i can makesure the hinges dosn't get bunched up in the slot.

Plus if I made the slot wider then the thin CA hinges...CA is not going to make up for the gap.
So, i use epoxy to make up for the gap.
It's not was noticable on the control surface..but you'll notice dimples on the wing where
the hinges are.

Sometimes I'll just CA the hinge to the control surface one at a time. But always
use epoxy to glue the control surfaces to the wing becuase I like to makesure the tips match.lol

It's not as if I'm going to go flying 1 hour after I glue the control surface.lol
The next day, I'll yank the heck out of the control surface.

Thanks a bunch, very clear now. I will do it according to MinnFlyer.


Séb

Great idea.

Mike: I was once told, and I don't rememer who it was that told me, that it was a good idea to push a pin through each side to hold the hinge in place. Now, that I think about it, your method does the same thing, doesn't it. Sometimes it takes a little bit of observation and a clarification from others (as you) with much more experience. Thanks for correcting that. I will adjust my 'building' technique accordingly.

CGr

DIck, where you may have gotten confused is that some people will pin the hinges into the wood AFTER they have been glued in as an extra safety measure. I even did this once when the CA I was using was old and starting to thicken (so I was afraid that it didn't soak in properly).

Some people do it all the time, but then, some people where a belt AND suspenders

Hey Minnflyer don't you always wear both. What keeps the belt from slipping down if you don't. By the way, good morning to you and CGR. I'm buyin coffee and english muffins with homemade strawberry jam.

Bring 'em over Gene. I'll make the biscuits and gravy!

What is Dick bringing.

Appetite!

Hey Bruceyou are coming too, aren't you. Could use some good old fashion pork sausage with a hint of sage.

It'll be in the gravy

It's to short a notice to get the ribs going, but in the future....

I've "pinned" CA hinges with toothpick sections pushed up from the lower (less visible) side in pre-drilled 1/16" holes. Back in my real belt-and-suspender days. I have come to trust CA hinges since and don't bother. My 14 lb G.P. Ultimate 43cc has CA hinges throughout (as do all but one of my models - that one has brass pinned Nylon hinges). I just take a lot of care in installing them and yank on the control surfaces as a pre-flight to make sure they're sound. Bennett Built sells 1/4 scale CA hinges and that is a good endorsement. As Da Rock said: I won't use a CA hinge that's not fuzzy.

And I follow Minn Flyers' tips - pin to center and pre-drill a hole in the slots to encourage CA flow.

I cut a bunch of fitting dummy hinges out of a milk bottle so I don't "wear out" the CA hinges during the building and trial fitting process. I think that may happen with over-handling when test fitting and using the hinges themselves to work the slots open. I use a hacksaw blade sharpened on the ends for that.