[CAUT] bridge cap sanding

[Jeff Farris]

David,

Thanks, just what I was looking for. I felt like I wanted to sand 
until the groove was gone - even though there is a mark left on the 
bridge. It would not be lower than before, yet it wouldn't have the 
chance of the old groove "wrapping" around the string to any degree 
either, possibly causing some termination problems.

I might try wiping the DAG off next time. The scraping is quite mild, 
usually with a razor blade, not a scraper. Just trying to keep the 
sandpaper from caking, and not create a mess.

And of course, filing the capo, replacing agraffes, and re-notching 
is all part of the main reason for doing this job.

Jeff Farris
Piano Technician
School of Music
UT Austin
mailto; jfarris at mail.utexas.edu
512-471-0158




>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.


-- 
Jeff Farris
Piano Technician
School of Music
UT Austin
mailto; jfarris at mail.utexas.edu
512-471-0158