[CAUT] bridge cap sanding

[David Love]

I wouldn't scrape the dag off, clean it off with denatured alcohol and a
rag.  Scraping makes it too easy to create an unlevel bridge top with the
variation in widths of the top of the cap.  Afterward I would sand down to
the bottom of the string groove or at least to the point where there is no
indention--sometimes there is a mark left by the string.  That's ok.  Since
that is already the level at which the string is resting, it won't change
the existing bearing.  If there is inadequate bearing because of the depth
of the string grooves then you either need to recap that portion of the
bridge or lower the plate.  My preference is to recap the capo section as a
general procedure in most cases.  Once you have sanded the bridge top flat
you will need to recut the notches with a chisel as the bridge cap
termination will have migrated out beyond the pin line.  Paying attention to
these details is everything in creating clean terminations and a more
focused tone.  Of course, don't forget the capo bar reshaping and the proper
dressing/replacement of the agraffes.  The devil is in the details!

David Love
davidlovepianos at comcast.net
www.davidlovepianos.com 


-----Original Message-----
From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of
McNeilTom at aol.com
Sent: Wednesday, January 23, 2008 3:55 PM
To: caut at ptg.org
Subject: Re: [CAUT] bridge cap sanding

Here at UT Austin, when restringing a piano, we replace agraffes and 
replace bridge pins. Standard bridge procedure includes, scraping off 
the old DAG, sanding the caps, gluesizing the pin holes, re-notching 
the bridge, etc. Here's my question/comment. When sanding, the old 
string groove is not completely removed, but it is minimized 
significantly. When I'm not trying to alter downbearing, just 
reproducing what was there (mostly), is that OK? In other words, is 
leaving a little groove a problem? Is removing it completely more of 
a problem or more desirable? Y'all have fun with this one.

Thanks,
-- 
Jeff Farris
shape in the new year.