So, here is the problem, cassettes are a great way to make a fiddle-yard but a complete pain if you want to make that fiddle-yard part of a continuous run. You need to be able to make the cassettes butt together tightly and align accurately but you also need to be able to get them in and out. If the ends of the fiddle-yard, where the cassettes join the main layout, are fixed at both ends then this is virtually impossible, either you will have a fit so loose that trains will derail or the cassettes will be too tight to remove.
I've attempted to solve this with 'the cassette clamp', the theory being that I can make one end of the cassette line be able to expand and contract to allow the cassette to be inserted. Only about 10mm of movement is required. The base for this device was cut from 2 thicknesses of 3mm ply while the operating lever and pinion gears were 6mm ply. Moving the handle left and right moves the expansion section forwards and backward.
The rail expansion joint was made from a pair of old switch-blades which were filed to a sharp point. The intention is that this joint will be taken in the trailing direction though it seems to work pretty well in both directions.
With the lever to the left there is about 10mm between ends of the rails and the cassette can be lifted out easily.
Moving the lever to the right pushes the moving section of the clamp to the left and tightly aligns the cassette.
There is a little video clip on Youtube to demonstrate.
This is the first iteration, will probably need some refining but we will see how it goes.