Installing the surface control horns is a rather arduous task, just like most of the finishing jobs with any aircraft. I chose to leave the top covering in tact and drill the hole, then screw in the bolt to just under the covering. I used a 1/8 inch drill bit, not the 9/64 that Tom's instructions talk about, and took special care to clean out the sawdust every eighth inch or so as I was drilling the hole. By grinding the tip of the bolts to a 45 degree angle about half the diameter the bolt could freely cut threads in the hardwood. I screwed in the bolt then took it out to strengthen the threads in the hardwood block with thin CA.

I screwed the bolt back in, measured 1-1/4" from the center of the control surface and added 3/16" before cutting the bolt off. I am going to use 1-1/4" servo arms and I want a one-to-one ratio from the servo arm to the control horn. This gives me the needed clearance for the pushrod as the surface deflects on high (3D) rates, as well as the full torque rating from my DS 8611 servos. The 3/16" was added to compensate for the attachment nut for the pushrod that threads down onto the control horn. I want 1-1/4" from the center of the control surface to the center of the pushrod, not the top of the pushrod attachment nut.

To keep the hot piece of metal from burning my covering, I put some blue masking tape on around close by where I would be cutting. This prevented the sparks from burning the covering while I cut and kept the area clean too. It pealed right off when I was finished and went on the other side for cutting.

Perfect geometry is the key to perfectly matched elevator halves. I don't want to fight any crazy mixing, I've got my own learning curve to battle against.