Switches are a perfect example of how I suck at track planning.

I drew the curve, then the tangent, and measured the divergent angle. It's a #6 turnout. If I place my Shinohara #6 turnout over the sketch with the frog at the tangent point, it looks like it ought to be a number six. But if I connect the flex track to the switch and try to make it fit, there's no way.

I haven't the slightest idea how to figure out what number switch I'll need without physically owning the switch, connecting it to flex track, and laying it on the bench. Then, and only then, will I have a solid idea what number I'll need to make everything fit. It's the Lionel method of track planning: Piece it together until you find what works.