[pianotech] Force equivalents in different actions

[Gene Nelson]

> What kind of soundboard and scale are on this piano.  Did you build a new
> board and new bridge for this one?  The original Knabes are a bit all over
> the place with very high tensions through the tenor region but not so high
> tensions in the treble.  I'm not arguing that the heavy hammer is "bad" in
> terms of tone.  Only whether it's appropriate in a given situation (touch
> weight aside).  A heavier hammer won't necessarily compromise clarity in 
> the
> treble in my experience, but it depends on the scale and soundboard
> response.  On an old Steinway with original and weaker board this hammer
> might not be a good choice depending, of course, on what you're after.

***  The new board is relatively thin - 8mm with radiused ribs - 16 of them, 
designed to support
a calculated bearing load and give a known amount of crown. And
an appropriate cut off bar. Bridge is
capped with laminated maple veneer and the bass cantolever removed. Board is
cut of and floats in the bass. Bearing load can easily be adjusted and is 
very light.
The scale is modified as the original had quite low tension and was all over 
the place
as you describe. It is now in the mid 160's for plain steel wire. Bass was 
custom as well but I
did not have a cooperative string maker but that is another story.
Even with the high sw, adding some weight to the treble bridge - 25g - 
helped the tone because
the board is very responsive.
As I am relatively new to this, I have learned considerably more about 
design from Dale and
Brett and hammer mass is very much a part of it - not so biased to heavy 
hammers as I was
and I am learning how to make more balanced choices.
Gene



> David Love
> www.davidlovepianos.com
>
>
> -----Original Message-----
> From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On 
> Behalf
> Of Gene Nelson
> Sent: Wednesday, March 24, 2010 3:21 PM
> To: pianotech at ptg.org
> Subject: Re: [pianotech] Force equivalents in different actions
>
> I have restored an older Knabe - as it was my piano I chose to experiment.
> After stringing I used a few hammers and ended up with Peter Clark's
> Classical West hammers - they are big, dense and cold press - similar to
> Isaac's.
> Strike weights are quite heavy - 13.5g at A0 and tapering along a typical
> Stanwood curve for that range.
> The action geometry was altered to accommodate and the ratio is quite low
> with 10.3mm dip and 45mm blow. Three and a half leads in the bass and
> tapering to one on the hammer side of the top three. I also like low
> friction so the touchweights are all 52g down and range evenly from 32  to
> 38 up from bass to treble. Checking is set at 6.5mm right now - WNG checks
> allow this. It feels and sounds good to me.
> After Del's class - spent the day today reducing bearing - especially in 
> the
>
> bass/lo-tenor and did improve the tone slightly.
> I have been lectured about the down side of heavy hammers to include much 
> of
>
> what you say about the force that hits the string - slower moving from 
> heavy
>
> and faster moving from light but overall power/force the same - wear and
> tear on bushings etc. I do listen, believe me.
> I think that the point about action saturation cannot be excluded as
> certainly everything flexes more with heavy.
> The hammer will only accelerate so fast and how would anyone know if you
> were at the saturation point? That would remove anything resembling a 
> linear
>
> relationship and put an upper limit on force applied to the string.
> Maybe WNG shanks can help reduce saturation but that is another story.
> And the tone is different. I believe felt resilience plays a roll.
> I have also been lectured that heavy in the treble is not good - with 7.5g
> sw at G7 I have great power and clarity - go figure. If the hammer string
> contact is calculated on the high side, it is not muting any pleasing
> harmonics anywhere on the piano. Lowest 4 notes excluded.
> Ready to get hammered publicly.
> Gene
>
>