It may not be out of place to explain why I do this. Most Composite planes are supplied with what is incorrectly called Phenolic Horns, I say incorrectly as Phenolic is a process and not a material, therefore it is impossible to determine what the original horns are made out of, the first plane I did this on was an Xtreme Composite Edge 2x2, I just did not like the lack of stiffness of them, the next one was a Composite ARF, these horns where in my opinion diabolical, they even came with a warning not to use ball links as the surface would flutter and the horn would break????????? Having now applied a stress test to both of these manufacturers product (give them a good bend in your fingers) the Xtreme Composite will take twice as much abbuse than the Composite ARF, they are also darker in colour and much stiffer and may be able to take a ball link in standard form, although I would not trust them on one of my planes.

Onward:

Next in the line is to source your materials, the way I make mine is with a cover plate too the slots to tidy up the area where you normally see a glue line, this in turn means an extra sheet of material, I use 2mm (0.077") and 0.75 (0.030") carbon sheet obtained from Carbon Copy in the UK, this is a very high quality carbon glass composite sheet, I will find a link and post it latter.

Next how much movement do you need on each surface, you need to know so you can determine the length of your servo arm and horn length, if you are doing this on a 3D machine you will have a long servo arm and possibly a short horn, to get the maximum resolution from your servo's do have the shortest servo arm you can use, even cranking up the ATV too maximum to allow the shortest arm possible, once you have decided on your horn length mark this on a piece of paper from the bottom surface to the hole in the horn using the original horn as a guide, draw around the top and bottom of the oringinal horn to give a rough outline join up the areas and you have your template for the first horn.

Mike