When converting a locomotive or truck to 3 rail sometimes there just isn't a pickup roller that will fit. My solution is to attach the roller to the truck or loco bottom with 0.025" phosphor bronze wire and 1/8 plastic sheet. First I cut the roller and support from a roller mechanism in my parts box. You can see the uncut roller on the left and the one where the roller and support have been cut off:
Four 0.025" holes were cut into the support and the phosphor bronze wire was inserted. You can see in the photo below where the wire was inserted into the holes and bent around the roller support to hold in firmly:
How the wire gets bent depends on where it has to go. This roller is going into some Scale City Design (old Walthers) Fox trucks. The phosphor bronze wire is a springy wire (The springs in KD couplers are made from it). The trick is to make the wire long enough so it flexes like a soft spring. Fox trucks are small so I'm going to have it hanging vertically between the bolster and axle. I'll bend the wire under the bolster and attach it to other side of the bolster with some plastic. Here is the finished assembly with the 1/8" plastic part the will be screwed to the bolster.
The little piece of wire sticking out on the right side will have an electrical wire soldered to it to carry the current to the tender. Here is the roller assembly attached to the truck:
How you bend the wire and make the plastic insulator will depend on the application. What I've shown in the photos is good for two axle trucks. If I needed a roller to go under a small drivered steam engine I'd position the roller horizontally and cantilever the phosphor bronze straight into a plastic block.
I've added rollers to a ton of locomotives, but none that I had to create something like that. However, I'll remember that sky-wire solution, it might come in handy some day.
