When I installed my latest pull-pull system, I decided to make use of a bit of modern technology... Lasers. In particular, I got one of those laser levels for Christmas this past year and found that they can be very beneficial when doing installations like the pull-pull. They shoot a perfectly straight line, which is also a perfectly flat plane. Most of the laser levels can be attached to a tripod. In this particular case the pull-pull servo is located in the cockpit area. I set the fuse upright on a flat table and placed the laser perpendicular to the fuse and shot a laser line along the side of the fuse... the line past from where the servo arm is to the control horn. While the laser line is illuminated on the fuse, I placed a small piece of low stick masking tape in the area where the cable will exit the fuse, with the laser line riding on the top edge of the tape. (tape was about 3 inches long). I did the same for the other side of the plane. Now for step 2, I placed the fuse on the floor and mounted the laser level to a tripod. I placed the tripod so that the laser is directly over the pull-pull servo and again shot a line from the servo arm to the control horn. Where that laser line crosses the top edge of the tape is exactly where the hole should be drilled.
I tried this out as kinda an experiment, but found it worked easier and better than I expected...after I had drilled the holes they were EXACTLY in line. My control wires touch NOTHING between the servo arm and control horn.
I have also discovered that the cheap key chain type laser pointers also come in handy for shooting down surfaces or through fuselages to find obstructions or nonconformities... it's like having a perfectly stiff wire that does not bend, but is much easier to use than a wire.
Happy pulling,
SkyBound