Touchweight Goodie

[Richard Brekne]

Isaac OLEG wrote:

>Richard,
>
>Again congratulation for all the deep understanding you provide in
>those matters.
>
>I am unsure to understand what the trick is for changing key ratio
>slightly , can you please explain a tad more ? is it the insertion of
>a leverage point in front of the pin ? never heard of such a trick,
>that is interesting.
>  
>
You can do this several ways... and evidently gain (one way or the 
other) up to about 3 grams of BW this way.

Basically, you add a little extra material to the underside of the key 
stick either forward or in back of the balance rail pin.  Which is the 
equivalant of slightly moving the fulcrum either forward or backwards. 
You have to be real close to the pin either way or you get no effect or 
even can cause some problems.

A Bluthner that I am doing seems to have a big problem with the balance 
rail as the Balance Weight Ratio is like all over the place in spite of 
dead on SW's and matching FW's.   I used Stanwoods publicized FW 
maximums and used a numbe 8 SW curve... so whatever BW I ended up with 
should have been at the least very consistant.  It was on target 
allright... but the variances are huge.... from 43 grams at the high to 
33 grams at the low... and there are quite a few keys that are off.  The 
only real tendency I see is a general leaning towards a lower BW (and 
ratio) as I get up into the higher treble.

I fooled around a bit with adjusting the key ratio this way this evening 
and will be able to even most of it out this way.  The rest seems 
regulation dependant as the knuckle line is really good on this 
instrument.  I'll have the keys off again tommorrow to take a closer 
look at the balance pin line as I am really curious about this one.

>I have to understand that one before looking at the spreadsheet more,
>but it seem that you raised a point that was really unclear to me in
>the formula.
>
>  
>
I am not sure I understand what you mean here... re-phrase ?

>thanks
>
>Isaac
>
>  
>
Cheers
RicB