TromboneChat

How misaligned a rotor could be until it feels leaky/un-centered?

I firmly believe that a rotor should be exactly “on the mark”, or at most ~5deg from it. But yesterday as I tried to align the F rotor on my school’s 50B3L (around 10deg off-mark when activated), the difference in feeling before and after alignment was slight, if any.

The marks can be completely wrong. Look down the valve passages to see where it actually is.

I've heard tell that the marks on Bachs are more often incorrect than they are correct. Just about the only configuration where they are sure to be wrong is when they're lined up! Probably should take it to a tech anyway, if you're looking to visually align it... its something where a very subtle degree of change can make it feel wrong. They'll look inside it and make sure everything is lining up.

The ONLY sure way to align the rotor ports is to look inside, best way is through the slide receiver.


Eric

Some valves have more tolerance than others. I like seeing valves that provide a step-less transition between the casing and the rotor, but quite a few valves are built with a misalignment between the "U" in the rotor and the "O" in the casing. If there's a step down to the "U," you can have as much as ten degrees +- and still have no obstruction to the air passage.