[CAUT] Down Weight Too High With New Hammers

[David Love]

Until we have more info from Paul it's difficult to know what to suggest.
The original is probably 16 mm and Paul has changed to 17mm on the knuckle.
That will increase the dip specs but .415 is a fairly deep dip and would
suggest an action ratio that is on the lower side already (assuming that
measurement is accurate).  So unless the hammers are really monsters (which
they could be) then I would expect one to be able to achieve a reasonable FW
even if it is with a moderately higher BW.  A direct measurement of the
action ratio (6 mm dip causes hammer travel of x?) would be helpful.  As was
mentioned by several contributors, friction readings need not be a mystery
and can easily be ascertained by a survey of the UW and DW through the
keyboard.   Remaking the keys certainly would solve any questions and
problems but it's not in the cards for this job.  Still, having redone many
of these actions without remaking keys there are always solutions.  But
without the data it's difficult to know the limits of what is achievable and
the best way to get there.  

 

David Love

www.davidlovepianos.com

 

From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of Brent
Fischer
Sent: Wednesday, August 25, 2010 6:58 AM
To: caut at ptg.org
Subject: Re: [CAUT] Down Weight Too High With New Hammers

 


 

 

Hey guys,

 

   David, I know it is counter-productive to increase

interia by moving leads to the front. We know Steinway

fit the action to the strike line therefore moving the

capstans away from the theoretically correct position.

Hamburg fits the piano to the action which is why

I've seen so many prefer it over NY. I am interested

in your solution given Paul's constraints. I believe

the original knuckle dimension is around 15.5 mm?

I found this always increased dip when going longer

however am not an action designer, but have had Roseland

Piano re-manufacture several of this vintage keyboards

with corrected ratios and it was the answer to being

able to lead closer to the balance rail with great results.

 

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