Baldwin

[Christopher D. Purdy]

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Richard,

It's not uncommon to have bass bridge glue joints fail.  I've seen it 
at the apron and the sound board.  The question here, I think, is do 
you have crown and down bearing?  Take a thread and from the bottom 
of the board, stretch the thread from one end of the board to the 
other with the grain.  Pull the thread tight  at each end and the 
center should be a quarter inch or more from the board.  If the 
thread is straight, that proves that the sound board bows (or crowns) 
up in the center.

Next, take a down bearing gauge and check for positive bearing at 
several points on the bass and treble bridges.  If there is positive 
bearing and the sound board has crown, you're fine.

I like to use tight bond wood glue in this case.  The trick is 
clamping.  In most cases I have had the bridge pull away from the 
apron.  I drill and countersink four holes in the bridge, glue, and 
send in wood screws to pull the joint together.  (I leave the screws 
in, just make sure you countersink enough that a string doesn't lay 
on the screw)

In the case of the apron loose from the board, you can use the same 
process but the screws go in from the back of the board and into the 
apron riser.  It is possible to remove the screws after the glue 
dries and then drill and plug with a dowel.  It may look a bit nicer 
but I leave the screws in.  I think it's stronger and easier.

The reason that down bearing did not hold the bridge down, assuming 
there is bearing, is that the last three strings are so close to the 
edge of the board.  The board has crown but the bridge riser is 
straight.  When it is glued to the board, it is forced to bend to 
meet the crown.  If the glue joint fails, the riser will try to 
straighten itself, hence the gap.

You also mention that the bridge is cracked.  If you mean cracks at 
each bridge pin, that's another repair, and that repair depends on 
how bad the cracks are.  If the bridge cap is cracked up and loose 
from the board, it might be a good time to replace the bridge, or at 
least the cap.  Send more information on all the above and we'll talk 
more.

chris



>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


-- 
Christopher D. Purdy R.P.T.
School of Music, Ohio University
Athens, Ohio  45701
(740) 593-1656
fax (740) 593-1429
purdy@ohiou.edu
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