Baseboard joints.

The following photos should help to explain the system that I have been using for several years on my various layouts and on an Area Group layout that is in process. The idea stems from a desire to get the indexing of the track joint as close to the rail heads as possible.  
The examples shown are for a section that is double track, the joiner is just as effective for single track or multiple adjacent tracks.  The joint does not need to be at right angles to the track,  the sawcut that splits the joint can be at an angle.  Obviously you need to position the sleepers with care. ( I have an example where the sleeper is sawn diagonally across between the rails.)
The underside of the track joint also provides an ideal spot to make the electrical connection to the rails. 

The photos show the construction of the joiners, which consist of: :-
Copper clad PCB (Maplin - Low Cost PCB 100 x 220 mm  Code 34-0892)
PCB Terminal Pins, single sided. (Maplin - Terminal Pins Code 34-0610)
Ply sleepers punched with 1mm holes at rail centres.. - Cut your own or buy from stores.
Brass tube 1/8 inch OD.
Rod a tight fit in tube. (copper-coated brazing rod.)
and finally the rail, soldered to the rivets.
 





The tube is 1/8 inch O/D brass and the pin is a length of  copper-covered brazing rod.  This solders well and is quite strong.  
To achieve some degree of uniformity  I build several joints on one piece of printed circuit board at one time.  
The first step is to gap the copper side of the PCB to suit the rail spacings (the example shown has the unwanted land etched away, which gives a neat finish)  Then  four lengths of  tube are soldered on.  These must be parallel but their spacing is not critical providing they are not positioned where the holes for the rivets will be.  Use an old steel rule between two of the tubes as you solder them to the PCB.


The next step is to mark the positions of the sleepers and consequently the holes for the rivets.  I use a Templot printout for this which gives accurate positioning.   Baseboard shapes are shown on the Templot drawing which enables moving sleeper positions to suit the location of the joint.
Sleepers are then put in position with terminal pins projecting through to the copper side of the PCB and the soldered.



The Joint takes the position of the last two sleepers either side of the baseboard joint.  
On the photo below you will see in the bottom left corner the baseboard locating dowel hole.  (Home made but I think they are called 'pattern-makers dowels').  These are 10mm long and locate first as the baseboards are offered up, before the joint pins which are 5mm long.
Note that the track underlay is cut back by about 20mm.  The track joint is floating, not fixed.