I haven't done this myself but to me a good solution would seem like creating small brushes and gradually rotating them horizontally by a small amount (5?) and increasing their height by an even smaller amount (1? 2?) and placing them near each other in a circle formation around a central cylinder, while cutting off the choppy edges of the small spiral ramp brushes. Wow, that was a lot of words. I need to go have a drink.
The problem with that is that it's not precice enough for my tastes, and I would be unable to accurately get the small section.
You should never use rotations in small degrees like that (only in 90 degree increments). Your map will end up being a mess with misaligned brushes everywhere. You can do this with some fancy clipping planes. It may be challenging, but once you've done 90 degrees, you can just clone it and rotate.
Yeah, but I don't know how to do 90 degrees...
i suggest checking out the spiral stairs on seigecastle.bsp or zsiege.bsp and then going from there.
I'm not looking for spiral stairs, I want a spiral ramp. And clipping each stair would take too long/not work well.
Also, please stay on-topic in this thread.