I felt a sudden urge to install the turntable in the fiddle yard. It was more or less ready anyway. A discourse on its construction was in a previous entry (number 27) - and one even before that (number 15) showing the roller bearing I am using.

I mounted the assembly from underneath. Firstly, I attached 'wings' and packing pieces to the wooden base, as below...

I tested the assembly to make sure it would fit through the hole in the baseboard properly.

I then attached the whole assembly to the underside of the baseboard using contact adhesive to hold everything in place, having carefully aligned the rail positions marked on the turntable with the track plan on the baseboard. I finally put screws in from underneath to make the overall assembly immovable - and four more from the top, just to make sure.

More by luck than judgment, the alignment seems pretty well perfect, both horizontally and vertically. The turntable revolves smoothly, too. Phew!!!

There will be no mechanism involved in turning this turntable. I shall do that by hand with a simple handle on the top of the turntable itself. The locking and current supply will be with rods in tubes, a bit like the locking system I have used on the fiddle yard sector plate.