Thanks. Nope didn't use any A or B curves. The ones I have don't work very well and I don't like them.
The only place you need smaller risers is at the base when building and tower.
Using the smaller risers, you build up each turn: 1, 2, 3. Once you get to 4 small risers, you continue all the was up with Full Size ones.
The double spiral took some trial and error. I spent about an hour rewinding and pausing videos on You Tube.