After building many kits .040 thru gasser size with ca hinges I am convinced I''m doing something wrong. A search on this topic gives many instances of "never a failure after XXXXXXXXX years, etc. I''ve had somewhere in the neighborhood of 20 hinges fail always a complete separation at the hinge line with both halves remaining in place. The last straw was when the left elevator half fell off a quadra powered 80" profile. I inspected the other surfaces and sure enough, three others were broken. I was able to land it, but this plane was a disaster waiting to happen. BTW, the ailerons each had 8 giant scale ca hinges that came with the kit.

After marking center with one of those straddle gizmos, I freehand the slots with xacto then size and true them with a hacksaw blade. 4 or 5 drops of thin ca on each side, a couple of flexes of the surface to insure no binding and let set overnight. Apparently, I either am leaving not enough gap, or the hinge slots are misaligned, but the surfaces are always free moving and after all these years building I''m not all that bad with the xacto.

So what do you guys think I''m doing wrong? I''ve tried holding my mouth in several different positons, but none have worked.

Sounds like you are installing them right. The hacksaw blade may be making the slots a little bigger than ideal, but I don''t think that would cause them to fail at the hinge line.

It is pretty well accepted these days that a CA hinge will fail at the hinge line from overstressing caused by the very high deflections and constant surface movement of 3D flight, OR from high vibration levels, such as in a twin or when using a gas engine.

Could one of those be your problem?

Jim

Let me say this I have never had a Radio South ca hinge failure in 10 years..........I just completed a Yak with a 40cc gas and was out of the blue radio south hinges and used the ones that came with the kit. The forth flight was it''s last.... as the rudder ripped off (control rod held)and beat the elevator off......sheeese........... RS blues hinges or Robarts, and if I''m out assembly stops.

Live and learn....and learn again.

With your years of building, it''s very probably not your slot cutting technique. But there must be something you''re doing that results in such a high failure rate. I don''t know a modeler at any of the 3 clubs where I fly who has seen more than one or two failures in the last 3 years.

A tight hinge gap really should have a good effect, not a bad one. And freely moving surfaces says that you don''t have hinges out of line or canted.

So do you use some off brand hinges? Or have always used the same brand of CA? Don''t make your own hinges out of something?

Do you mark the centerline of hinges when installing? With what?

A friend of mine has had the same luck. I asked him to demonstrate what he does and he showed me. My assumption was he was using way too much ca....well at least way more than I use. I have not had the same issues he has. Maybe too much is no good? Not sure. Just thought I would add that since no one else did...maybe it is not a big deal? Not sure. I only use enough ca to soak up the hinge....he has enough to cause binding. I believe thats where he went wrong.

Kevin

Look at the pulled out CA hinge itself.

- Did it take the surrounding wood with it?

- If not is the hinge smooth and almost glasslike?


If the former the hinge was properly bonded with the wood but the surrounding wood "gave".

While some people here advocate only a few drops of wood, I frequently will add 8+ drops ( as often recommended ) along ths hinge slits on ARF''s to help harden the surrounding wood.

On some planes you can view how much penetration you are achieving by peeking through the wing root holes after the CA has dried.

If you cannot see the darkened CA hardened areas from behind, well past the hinge itself, you are not using enough CA and/or you have not placed holes or other CA distribution rivulets into the area first.


If the latter of the two above, the CA worked but the hinge material itself did not hang onto the fibers.

I have seen this with cheap asian CA hinge material.


Asian hinge material has fibers over a plastic base. The fibers CAN "give" way over time, leaving you with a broken control surface and a smooth CA hinge sticking out of the broken surface.

I''ve had this happen on two occasions with second hand planes...


The GP and Dubro CA hinges DO NOT have an inner plastic insert, rather they are fiberous all the way through.

I have never seen one of these give way... without first taking a large chunk of surrounding wood with them!

I suspect that you had the cheaper asian hinges.

Yes, max throws on 3D, lots of vibes from piped engines on Q500 types. But niether are beyond what I would consider "normal practice"

Using mostly Goldberg hinges or whatever came with OMP, Morris. None of these were the plastic sandwich type. I use a straight pin in the middle of the hinge for locator.

Yea, I get some ca in the hingline that is prolly making a fulcrum making the hinge try to separate. I''m guessing that along with max throws is the culprit.

Hinge does NOT pull out. It always breaks in half at the hinge line. If you miss the first one (which is easy to do cause the failure is not obvious) a couple of more flights will result in the entire surface coming off. In any case, I''m done with CA hinges. Just add $10 to every plane I build for Robarts.

Fulcrum...thats the word I was looking for. I believe thats what caused my pals issues. I do agree on the adding 10 bucks to each build. It is the way to go. I have broke robarts too but it was from rough landing not normal use. I use them in all of my planes now. Well worth the extra time and money.

Anyone want to fly in a full-size with CA hinges? No? Thought not. I''ve yet to see a thread on "all 4 of my Robart hinge points failed simultaneously and my aileron fell off" so why persist with CA hinges?

Answer: Cheap/quick/lazy.

I''m with you rideon67, bin ''em!

Cam

flat pinned hinges and hinge glue is so simple, you ought to try that before going the Robart route. Robarts are good, but you''ve already got the slots in ARFs. Hacksaw blade the slot. Squeeze in the hinge glue. Push in one side. The hingepin tells you where center is. Go down the surface slots with the hacksaw blade, then down the row with the hinge glue. Push the surface on and you''re done.

Give those flat hinges and the hinge glue a try.

I did a test when I first saw the hinge glue, and it works with Dubro''s perfectly. Had to destroy the wood to get the hinge out. Actually did not get it out at all, just destroyed the wood around it.

BTW, if you do go with the Robarts, try the hinge glue for them. It''ll hold them like they grew there. Beats epoxy for holding hinges because it won''t glue the hinging and excess wipes away with a damp paper towel.

Hinge glue rocks! I'll never go back to anything else after trying it.

MAYBE YOU SHOULD LOOK AT HOW MUCH GAP YOU ARE LEAVING !!! ( Sorry about the cap lock ) It seems to me that if you are getting the gaps too tight and then putting extra stress on them by doing 3D that the hinge would break in the center. Maybe the cure is to leave just a little bit more gap and then seal the hinge gap with monocote or clear tape. MY 2 cents !! ENJOY !!! RED

You make a good point, Red Head.

But I'm with the guys that avoid CA hinges on anything powered by an engine larger than a .53 (you have to pick a cutoff point somewhere!). I still like the flat nylon hinges (pinned or unpinned).

The hinge glue that everyone is talking about sounds a lot like the old RC-56 canopy glue. Any comments, anyone?


Ed Cregger

I am one of the "have not broken one in X of years". I think it has been 15 years. And I fly my stuff hard. It sounds like your are not gapping them right. I do mine as follows. I dry hinge the surface. Then deflect it a little past what the max will be. While pushing the surface against the wing or whatever and holding the deflection I apply a few drops to the first side. Normally I have the surface going down. So then I tilt the plane or wing the opposite way and do three or so more drops. The idea being gravity is helping the glue run both ways. Then I flip the whole thing over and do the other side. I have 3D planes with several hundred flight on them and the hinges are fine.
BTW if the ARF is from a lesser know company I use Great Planes hinges insead of the supplied ones. Just to be safe.

David

Ed, I use the 56 canopy glue (for canopys) and its not the same as the hinge glue. The hinge glue is much thinner than canopy glue, looks like thinned wood glue. When I first bought some and looked at it, I stupidly thought it wouldn't work very well. After reading some more comments about it and finally tried it, I was amazed at how well it works! [8D]

I use Radio south 1/4 scale hinges, and have found that they are superior to any other CA hinges on the market. I have tried Sig, GP (Both precut and cut your hinge material). The Radio South will not seperate from the mylar material like Sig and GP's will. I have experimented, and the only way I could break the Radio south's is with a vice grip, and then it still did not delaminate like the others.

AMEN to Radio South!

I wasn't sure about the hinge glue either. I did a test with some robart hinge points and some soft 1/2 inch balsa block with that Pacer Hinge glue. I went back the next day and tried to break it free and all I managed to do was twist the hinge point apart at the hinge with the free end. The side glued into the block didn't budge at all. I was sold after that. If I manage to make a hinge point fail, the rest won't matter anyway .