Usually, the bogie connection wires are passed to the light strip through the toilet, where a rectifier and a capacitor are also placed. But, in the Nord Rapide coaches, the toilets are in the center! There is no discreet path for the wires, except maybe between chassis and interior fittings. But the place is occupied by a ballast. I tested this solution: it is tricky to keep the wires in this position. So I tried something else: make the wires pass into a compartment partition thickness!
There is another solution I would have used if I had known it at that moment. It consists of using self-adhesive copper tape. Thin as the tracks of a printed circuit, this tape would pass without any problem between chassis and interior fittings.
This is feasible: the partitions are 1.2 mm thick in their thinnest part, and there is only about 8 mm to run through “uncovered” before passing behind the seat backs, which can hide an accidental exit of the drill bit. I think I can drill at ø 0.6 for wires ø 0.5.
Naturally, the inside fittings to be drilled must be firmly held in a vice and perfectly horizontal.
To deflect as little as possible, I start with a carbide drill bit (1), very rigid (and brittle!), but too short to reach the bottom. I finish with a classic drill bit (2) very, too flexible. It is necessary to work at very low speed, otherwise the material warms up and deforms.
It is also necessary to often lift up the drill to clean it, let us say every millimeter of tool advance. Two holes must be drilled per partition, one per wire, to a distance between about 3 or 4 mm. Even with all these precautions, I could not avoid getting out a little too soon, but it did not go too bad.
Here are the wires installed. I was afraid of difficulties in introducing them, but it went well. It is important that they slide easily, to get the excess under the roof after soldering them on the bogies.
It's not over: when the body is reassembled, its crossing beams with their pretty, though almost invisible, luggage racks will position themselves just above the partitions, risking to block the wires. These crossing beams must therefore be drilled, or rather milled. Obviously, the milling must be right above the partition holes.
I prefer that the entire lighting system be independent of the roof, so that it can be safely removed. The light strips are therefore not sticked on the roof, but on the body, by means of spacers, with thick double-sided adhesive. These spacers are cut in 4 mm thick polystyrene. On a total of three, two are glued to the extreme body crossing beams (1) and one is located towards the middle of the car, depending on the possibilities. The gluing is made with liquid model glue, like Kibri’s.
On the first finished car, I noticed light leaks between the body and the roof, especially at the doors. So I glue a 1 mm square Evergreen profile (2) all along the body behind the roof clips. This gluing is also done with plastic model glue. There is of course a profile on each side. These profiles will be painted black.
Copper foil tape
5 mm x 30 m adhesive