This is the sort of thing I've tried:

I'm trying to understand why in that patch the phasor~ stops? It seems like this shouldn't happen as I'm just trying to trigger the sah~ with the output... explanations welcome!

Maybe this is what you're looking for?

No I'm afraid not. Perhaps I confused it with my example. This isn't about phasor~ ramps. But nice patch anyway - no doubt useful one day.

I'm playing sounds with wave~ (actually a version of wavefade.maxpat from examples) and want to adjust playback position, but with those changes only taking place on zero crossings to avoid clicks.

So I want to have a control signal going into the patcher for the start position, say 0.4, then when I change that to, say, 0.6 it waits until a zero crossing to take effect. I thought I was going to be able to do it with sah~ but it holds until a signal is above a certain level. I need a sah~ which only changes when the value is == 0. If that makes sense?

Yes, I think I understand now, though I'm not sure if I can help since I'm still fairly new to Max. Is this on the right track? Please forgive me if I have no idea what I'm doing haha.

Guess not.

phasor~ to delta~ to <~ 0. to sah~ should do the trick.