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.Why dont you solder your wire spans to the upright rails/poles instead of drilling through them. You can bend the ends of the wire spans at right angles that will make a easier connection. For me the "K"braced spans are easier than wire spans.There are more soldered conections with wire spans.
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.As far as steel vs copper wire I have found out that if you plan to energize your wire to run trains copper works best and is easier to solder and maintain.