Bridge attachment

[Richard Strang]

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Help!!!
   I took some string measurements today from the Baldwin M grand I am going
to replace the bass strings in, and YIKES, I found the bass bridge cracked
and broken at the third string. What bothers me is that the 3 inch section
was floating about 1/8 inch off the sound board. Shouldn't the down bearing
keep it down???? I have never repaired a bridge before, so I could use any
coaxing I can get. I took the bottom three strings off so I could put the
broken part back into it's normal position in order to make the string
measurement. I imagine I should use an epoxy glue to repair this, right, or
can I use thick CA??? It's a very clean break and the pieces can be put back
together and one can hardly tell it's broken. Please advise. Thanks.

Richard Strang
Panama
  -----Original Message-----
  From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org]On
Behalf Of Delwin D Fandrich
  Sent: Friday, July 25, 2003 4:34 PM
  To: Pianotech
  Subject: Re: Bridge attachment



    ----- Original Message -----
    From: BobDavis88@aol.com
    To: pianotech@ptg.org
    Sent: July 25, 2003 1:40 PM
    Subject: Bridge attachment


    There are obviously several ways to clamp a bridge to a new soundboard
while gluing - pneumatic press, go-bars, screws with their holes later
filled with dowels.

    Suppose one is using screws. I have heard several people say they don't
like to drill through ribs. The old Steinways had a combination of screws
through every rib which were then dowelled, large dowels  up into the areas
between the feet of a footed bridge, and screws through soundboard buttons
in the high treble which were just left in place. Is there a better way, if
one is using screws? It seems like drilling through ribs weaken the ribs, a
hardwood dowel through a thin softwood soundboard between the ribs could
break free later and buzz, and a screw left in place through a soundboard
button could loosen and buzz, especially since many are inaccessible.
  Drilling through the rib does weaken it. This is not a problem if the
soundboard is compression-crowned. In this case the rib is not supporting
crown, but resisting it. It needs to be some flexible.

  In the case of a rib-crowned soundboard system the rib is a structural
member. It is not a good idea to do anything that would weaken the rib right
at the point where you are putting the most stress on it--directly under the
bridge.

  Most of those who use screws and buttons to attach bridges put them in
between the ribs, not through them.

  It is true that a screw left in a soundboard could cause a buzz sometime
down the road. But then so will a loose rib. Perhaps we should leave the
ribs off as well. Seriously, enough screws have been left in enough
soundboards over the past 150 plus years that if this were going to develop
into a severe problem it probably would have done so by now.

  Del

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