Solder Paste

Thank you both, very much for the interesting comments and good to know it is deemed to be useful. It's clear now why the Solder Paste would be the better choice, in this circumstance and other similar ones.

The reason for the choice of some form of alignment system is because of the steep angle that most of the tracks cross the Board joins {Thin red lines}. Even at that, any slight discrepancy would take a lot of fiddling to make sure of decent running, I have Pattern-Makers Dowels and double bolts at every board join, which turns out to be pretty effective. I decided that track inserts {Blue track sections} would minimise the effect of any discrepancies. Initially, I was going to use the simple, well tried, sliding Fish-Plates idea at the ends of the inserts.



Having seen these Track Aligners, It occurred that I could leave the Fish-Plates as purchased at one end and use the Aligners at the other end, for simple - push together - board assembly. The matching Aligners on the connecting track, would, of course, be firmly fixed to it's board. From what you have said, the close fit of rail to Aligner would be much easier with the Solder paste - result! Thanks again.

NB. Just to tidy up a loose end - the Aligners have a small hole in the centre of each of the 3 sleepers, which could well be used to drill a matching hole in the board underneath, so a track pin could be dropped in, to keep the two Aligners snug.

Good afternoon Babs,
I can see a couple of ways it might work, as the hinge end should lift away from the static rails and align perfectly every time it's lowered again, assuming that the hinge line is above the top of the rails. That should mean that the hinge end rails can be glued, or soldered to screws, to fix them to that end, in the way that many do. The additional advantage with screws is that their underside can be used to solder Bus connections to, so no problem with power supply.
Alternately, you might consider having the straight{?} track across the bridge loose, so that he normal Fish Plates at one end provide the alignment and power{?} with the other end using the alignment sleepers. I'm dubious about the second one, as vertical alignment at the alignment sleeper end, would need some form of clip, to ensure the rails didn't rise above the main fixed rails. Not impossible as a simple rotating or sliding clip would work, but not quite such an elegant solution as the first one.
{NB. It's ok when closing a gap, to connect 2 x separate baseboards, as the static rails can be extended slightly beyond their Alignment sleepers {5mm?}, so the sleepers on the loose track, tuck under them, to be held down, as the gap closes.}
A complete loose bridge, is also practical, with the track laid on it, normal fashion, such items have used small brass bolts to secure the ends and provide a power connection, too.