C/A hinge installation
#1
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From: Norwich, NY
I am a beginner to the RC airplane hobby and have a couple questions. I am building my first two ARF planes (trainer and stick) and have progressed to the control surface installation. Both sets of instructions indicate the hinges have already been glued into the control surfaces. They were not. So, I marked the center line of each hinge with a pencil and glued them into each control surface (rudder, elevator, and ailerons) using thin C/A. The control surfaces have not been mounted on the airplane yet. The thin C/A wicked up each hinge approximately 75% to the top of the exposed region of each hinge during this procedure. My first question is:
1. Does the hardened C/A on the exposed hinge impact the integrity of the bond subsequent to installing each control surface in the wings, vertical, and horzintal stabilizer?
My second question involves placing pins in the C/A hinges. Although the directions do not recommend placing pins in the hinges, an experienced model builder recommended placing pins in each hinge. He suggested drilling a small holes and pinning each hinge with a toothpick and epoxy. My second question(s) is:
2. Do other experinced modelers concur with this recommendation? Do all the control surfaces require pins or just the elevator?
1. Does the hardened C/A on the exposed hinge impact the integrity of the bond subsequent to installing each control surface in the wings, vertical, and horzintal stabilizer?
My second question involves placing pins in the C/A hinges. Although the directions do not recommend placing pins in the hinges, an experienced model builder recommended placing pins in each hinge. He suggested drilling a small holes and pinning each hinge with a toothpick and epoxy. My second question(s) is:
2. Do other experinced modelers concur with this recommendation? Do all the control surfaces require pins or just the elevator?
#2

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From: Chesterfield, MO
The correct approach is to:
1) Mark the CA hinge with a crayon at the middle of the hinge (where it will bend). The wax of the crayon keeps this part flexible, and the color helps you make sure the hinge is inserted equally into both pieces.
2) Cut slits into both surfaces with a #11 knife if they are not already slotted. Do not remove any material from the slits -- just make a slit in the wood.
3) Install all hinges into both surfaces. Because you only have a slit, the hinges will stay put from the friction of the tight fit. Double check that the surface moves freely and that all hinges are properly into both surfaces.
4) Now, you can get out your bottle of THIN CA. Deflect the surface all the way in one direction and put a few drops onto the hinge that is just barely visible in the crack between surfaces. The surfaces should be pushed tightly together so that there is very little gap. The drops of CA should be dropping on the line drawn by the crayon and it will wick into both surfaces at the same time.
5) Now turn the surface over and deflect the surface the opposite way. Put a few drops on this side of the hinge, too. Some of the CA hinges have a plastic layer as their middle layer and this way the CA is on both sides.
If you do this right, the surfaces will never come apart without removing serious chunks of the surrounding wood.
Sounds like it may be too late on your project if you have already applied the CA to the hinges. You could still try my method and hope that the hinges still have enough wicking action to work. Or you could cut off the hinges and buy some new ones. Cut new slots next to the old ones and do it my way. I would try to use the ones you have already installed. When you are all done, just give each hinge a good tug to make sure it has worked. If the hinges fail, then cut them off and go again with new hinges.
1) Mark the CA hinge with a crayon at the middle of the hinge (where it will bend). The wax of the crayon keeps this part flexible, and the color helps you make sure the hinge is inserted equally into both pieces.
2) Cut slits into both surfaces with a #11 knife if they are not already slotted. Do not remove any material from the slits -- just make a slit in the wood.
3) Install all hinges into both surfaces. Because you only have a slit, the hinges will stay put from the friction of the tight fit. Double check that the surface moves freely and that all hinges are properly into both surfaces.
4) Now, you can get out your bottle of THIN CA. Deflect the surface all the way in one direction and put a few drops onto the hinge that is just barely visible in the crack between surfaces. The surfaces should be pushed tightly together so that there is very little gap. The drops of CA should be dropping on the line drawn by the crayon and it will wick into both surfaces at the same time.
5) Now turn the surface over and deflect the surface the opposite way. Put a few drops on this side of the hinge, too. Some of the CA hinges have a plastic layer as their middle layer and this way the CA is on both sides.
If you do this right, the surfaces will never come apart without removing serious chunks of the surrounding wood.
Sounds like it may be too late on your project if you have already applied the CA to the hinges. You could still try my method and hope that the hinges still have enough wicking action to work. Or you could cut off the hinges and buy some new ones. Cut new slots next to the old ones and do it my way. I would try to use the ones you have already installed. When you are all done, just give each hinge a good tug to make sure it has worked. If the hinges fail, then cut them off and go again with new hinges.
#3
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I agree... It's too late to use the hinges as they are meant to be used because they will no longer "wick" the CA properly.
The good news is it's not too late to still use them.
Go ahead and install them using the traditional method, but then use your friends advise and drill a small hole and epoxy (or CA) a round toothpick through each hinge.
The good news is it's not too late to still use them.
Go ahead and install them using the traditional method, but then use your friends advise and drill a small hole and epoxy (or CA) a round toothpick through each hinge.
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From: Garrett Park, Maryland
2. Do other experinced modelers concur with this recommendation?
The issue of CA on the exposed portion is not one of affecting the bond, but whether it makes the hinge less flexible, and over time, leads to the hinge breaking. In my experience, the CA on the exposed portion just flakes away over time, and it's hard for me to believe that any reputable company would make CA hinges that are attacked by CA itself (you've got to give the manufacturers credit for *some* integrity). Personally, I've never had a CA hinge break, but then again, I've never put 100's of flights on a plane either. Other people have had different experiences, and that's where the crayon method had its start.
On the issue of pinning, I think most experienced builders do not think it's necessary, assuming the CA wicks well, and the slots are the correct size, etc. On the other hand, pinning is very easy, so you may be more comfortable with the extra level of safety.



