Bridge pin angle

[Phillip Ford]

Given that you haven't been following it you seem to have done a pretty 
succinct summing up of what we've been jabbering about for two weeks 
now.  A couple of comments below:


>I've not really been following this discussion in all its detail so this
>may be an already expressed opinion but here's what I see happening.
>Under any conditions, with sufficiently angled bridge pin that is
>unnotched, there is no way for the string to ride up the pin--period.

I think I would agree with - under positive downbearing conditions.  I'm 
not sure what will happen with negative downbearing, but it could be that a 
string having sufficient sidebearing wouldn't ride up a sufficiently angled 
pin even under negative downbearing conditions.

>But as the bridge top expands and contracts the edge of the bridge
>becomes indented more than the top of the bridge because of the
>squeezing with changes in humidity against the bridge pin.  Now when the
>bridge shrinks the line of the indentation at the edge of the bridge
>will not be on the same plane as the top of the bridge.  Because of the
>stiffness of the string and its tendency to want to stay on the plane
>formed by the top of the bridge, the deeper indentation at the edge of
>the bridge can cause a gap to form underneath the string at that point.
>Tapping down the string will cause the string to move, but it is a
>temporary measure.  The string will want to regain it's original shape
>and position.

I agree that it will want to regain it's original shape.  However, after 
you tap it down there is still considerable friction between string and pin 
that I think will keep it down there and keep it from rising, at least for 
small indentations.  If you have a severe enough indentation, then you 
would have to push the string so far out of its path that the upward 
component along the pin of the string tension would break the friction and 
cause the string to rise up off the indentation.

>Over time, and not probably very much time, it will
>unseat itself from the low indentation at the bridge edge reestablishing
>the gap and giving the illusion of it riding up the pin.

I think it will be pushed up by the cap on the next wet cycle.  On the 
following dry cycle the cap will recede leaving a gap.

>Tapping down
>may work for a short time, but it also probably exacerbates the problem
>by further indenting the edge of the bridge.  Either way, the string is
>not climbing the bridge pin and the better solution is to use some kind
>of bridge top material or preparation that makes it less prone to
>indentation.  Delignit material seems to be the hardest in use that I
>know of, but does require a power notcher.
>
>
>David Love
>davidlovepianos@comcast.net

I'm not sure why Ron decided to develop his own capping material rather 
than use Delignit.  Ron, what say you?

Phil F