Posted by Rick Denney on June 07, 2002 at 13:19:03:
In Reply to: Re: What are they? posted by Learning on June 07, 2002 at 13:05:20:
It is true that the springs don't much affect the lightness and speed of the mechansim, but they are different. One advantage to the clock springs is that the outer surface of the barrel restrains the outer part of the spring. Some of the spring is wound tightly on the shaft, some is unwound tightly inside the barrel, and some is floating in between. The in-between part is what's doing the work. With the barrel, a consistent amount of spring is exposed at any time, so that it applies a very consistent return force on the finger. The wire springs are harder to press the more you press them.
Clocks use this approach to keep the spring from overpowering the escapement when freshly wound and underpowering the escapement before needing to be wound again. Clocks that use the barrel tend, therefore, to be a bit more accurate than clocks with free-air springs, though the latter were cheaper. Of course, a tuba linkage spring's full winding range is less than a quarter turn, so it doesn't really matter. It's entirely likely that the clock-springs were bought from clock suppliers as commodities by the tuba makers, but that's a pure guess on my part.
The effect is subtle--too subtle to be worth the bother of clock-spring construction--but they do have a different feel.
Rick "whose former Musica F tuba had old-fashioned clock-spring linkages" Denney