H9 slots the center of the ca style hinge so that ca can wick to the ends easily. For some reason I prefer to use the Great Planes hinge material cut to 1" x 1" squares or larger for larger planes. I also like to drill a 1/16" hole into the balsa where the hinge will go to allow the ca to wick in quickly.

Make sure the ca hinge will fit the slot. You don't want it so tight that you risk crimping the hinge when you install it. You don't want it so loose that the hinge material can't get a tight bond. I recut the hinge slot on every ARF I build with a slot machine, makes them just right, plus with the wider hinge I like to use it easy to widen the slot.

Trial fit everything together with pins placed in the center of the hinge material so that the hinge material will be evenly distibuted in the parts. I first place the hinge in the aileron, rudder, elevator, etc then working from the outside edge slowly work the hinges into place, if you get bad binding going in pull it apart, clean out the slots again and retry.

When its together and you are satisfied with the fit use a fine felt tip pin and put a small mark on the control surface close to the pins, then pull the pins. Shove everything together so there is no gap. Grab the control surface close to both ends and flex it just past the desired deflection you will need while slightly pushing in to hold the hinge line together. This should give you the gap needed.

Lets discuss that gap for a moment. If you are going for 45 degree deflections, the surfaces must be beveled. Don't rely on a large gap between surfaces to achieve the deflection. You will have major slop in the hinge line. You should be able to see light thru the gap. if you can't its too tight and will stress the hinge material. If its a 1/16" the gap is too large. The gap should be the same all along the hinge line.

ONLY USE THIN CA. I like to apply the ca using a small capillary tube stuck in the bottle, it gives small drops right where I need them. I put about 5 to 6 drops per side of each hinge. Remember the marks you made of the surfaces, makes locating the hinge easy. When its all dry flex the surfaces. Do not go back and add more ca, it will not wick in and I think it will make the hinge line brittle.

Seal the hinge lines, this is important. If you don't know how do a simple search and you will find many discussion on it.

You will be rewarded with a long life hinge that will only fail by pulling the wood out with the hinge.

Ed M.