Once the roof has been disassembled (by two screws and a very light snap), one can find that a slot for a specific strip has been provided. The strip will be sandwiched between the compartment partitions and their counterparts under the roof. Incidentally, these ribs stiffen the roof perfectly. Again, why not have stiffened the top of the body the same way?
The remaining space is 8 mm wide by 0.8 thick. At the body ends, there are bosses obviously provided for snapping the strip. All this imposes practically the dimensions of the strip; it will be 251 mm long × 7.6 mm wide × 0.8 mm thick.
Here is my solution (valid only in digital). Click the image to see the whole circuit, in full size (140 KB PDF).
Even if I was in favor of the metal strips rubbing on the axles, this solution seems difficult to apply here, given the complexity and the detailing of the bogies. On the other hand, there are no brass bearings, and the space between the wheel and the guard plate is restricted. I guess REE wanted to conform to reality as close as possible.
I therefore tried a solution à la Roco, with thin plates doubling the bogie flanks and acting as conductive bearings. But this solution must be effective, relatively easy to implement, and should not lead to any additional friction, which would be counterproductive.
Here is the diagram of such a bearing. The bottom shape allows it to come close to the axle box and thus be virtually invisible. The electrical connection will be made from the top.
I cut 5 mm wide strips into 0.2 mm thick brass sheet. Every 8 mm (it could have been less), I “stamped” a conical shape, thanks to a pin axle and a matrix formed of a steel plate first drilled with a ø 1.5 mm cylindrical hole whose entrance was flared with a diamond mill bit, to reach approximately a diameter of 2 mm. The conical stamp must be large enough not to float in the bogie housing (to be correctly centered), but not too much to be able to tack properly.
Then the strip is cut into sections according to the diagram, each bearing is shaped, tinned on top…
The cutting tool visible in this picture is one of those that we regret not having known before. This is the Xuron 440 cutting pliers whose primary purpose is to cut photo-etched nickel silver. These are in fact scissors with short blades, very useful to cut thin sheet.
… and glued with cyanoacrylate, inside the guard plate. During this operation, it is held in place by a false axle that can be expanded to fit to the desired length.
Caution: the connecting rods of the brake shoes break like glass. Secondary suspension leaf springs are also very fragile. A bogie can only be held by the frame of the chassis or between two axle boxes.
Cutting pliers for photo-etching
24.80 € - price 2015
Miniatures Passion ref. XUR440