Because soldering straight to side of the rails doesn't work. the pieces to easily snap off. Anchoring it in some how will give the catenary extra strength. That is why i've decided to use Brass H-columns for my catenary structures. not only does this look more accurate, i can hide the anchoring close to the webbing, and things like grab irons and angle braces can hide the anchors. My dremel drill press is more than capable of doing the job precisely and quickly. I don't know. Copper wire is WAY to soft. Your wire has slight little kinks in it, and that doesn't give it that uniform smooth look that the prototype does. I think that in the future, my auxiliary wire will be steel, and the actually contact wire could be copper (the opposite from the prototype, ironically). the steel will hold the copper straight.