Posted by metrologist on October 19, 2000 at 09:52:39:
In Reply to: Can unaligned valve be repaired? posted by Tom on October 18, 2000 at 14:09:54:
What you are describing is technically a cylindricity problem,
in that the theoretical perfect cylinder in the theoretical perfect bore
isn't round around the entire range of motion (this variation is called T.I.R.
or total-indicator-reading when measured) This is a relationship
of different geometric elements (sounds impressive, huh?)
Out-of cylindricity in lay terms is out-of-round and/or out-of-straight
of things like tubes or rods, so the out-of-round AND out-of straight
variation for your horn is either in the casing (likely) or the valve
(a little less likely.)
Whichever, this seems/sounds like it has become a problem while playing.
Fixing the symptom often is treated as easier than eliminating the cause,
this is why you want to have a "good" repairperson do the work, as others have said.
Simply lapping in the valve to the casing might eliminate the symptom
for a while, BUT if the binding is caused by a tweeked valve branch
(as you suggest) that binding will likely return, as the stress
from the misalignment changes over time. Try looking up keywords
like
1) ANSI Y14.5
2) cylindricity
or
3) Geometric dimensioning
for more reading info if you're still awake and interested that is... ;-)
I know this was long-winded and maybe hard to understand,
but I figured I'd offer it as my '02-cent's worth.
-Dale