[pianotech] Downbearing question

[Al Guecia/AlliedPianoCraft]

Thanks Will. I usually read about 5 to 8 thousandths with my dial gauge 
micrometer and wasn't sure if 10 to 12 was too much.

Mike, the measurement is within one inch on either side of the bridge. I use 
a string to set the downbearing, but I like to check it when it's strung 
with a dial gauge micrometer. The readings are lower on a "B" or "D" of 
course, but pretty consistent on smaller pianos. After I set the downbearing 
and restring the piano I usually get about 6 to 8 thousandths in the bass 
and tenor and about 20 to 25 in the treble with my dial gauge.

The reason I need to replace the strings, is someone killed the bass strings 
by trying to clean them with some kind of cleaner. I decided to replacing 
the wire strings because I don't want two different size tuning pins and 
also to replace the agraffes and polish the v-bar which I can do without 
pulling the plate.

Al G

--------------------------------------------------
From: "Mike Spalding" <mike.spalding1 at verizon.net>
Sent: Thursday, July 30, 2009 7:52 AM
To: <pianotech at ptg.org>
Subject: Re: [pianotech] Downbearing question

> Al,
>
> Downbearing is an angle, not a linear measure.  10 to 12 thousandths only 
> has meaning if we know over what length of string it drops 10 to 12 
> thousandths.
>
> That said, if you have some amount of positive downbearing throughout, 
> then there may be no need to change it.  There are a lot of other reasons 
> to pull the plate during restringing.  How is it that this piano needs new 
> strings, but doesn't need any work on the bridges, agraffes, or v-bar, and 
> doesn't need a new pinblock?
>
> Mike
>
> Al Guecia/AlliedPianoCraft wrote:
>> I never got a response to this question. Did my email get through?
>> I am restringing a Steinway M. Before I pulled the strings I read a 
>> composite down bearing of 10 to 12 thousandths across the bass and tenor 
>> bridges with a dial gauge micrometer. My question is, how much 
>> downbearing is too much.  Is 10 to 12 thousandths too much. At what point 
>> would it be worth pulling the plate to adjust it. The soundboard and 
>> bridges are in good condition.
>>  Al G
>