Lighter or Heavier ?

[Ron Overs]

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At 12:41 AM +0200 14/7/02, St=E9phane Collin wrote:

>After all, go to Steinway Hamburg, and try 10 model B's.  Not 2 will 
>have the same sound.

Thanks to their CC sound board construction, and that no two 
technicians will voice a piano the same.

>Not 2 the same touch feel.  Though, they are made following the same 
>(computer controlled) uppermost demanding specifications.

I find myself having difficulty accepting this second sentence. If 
they were built to exactly the same specification they would 'feel' 
the same. I have rebuilt many Hamburg Steinways, and measured their 
hammer/key ratios. Therefore, I do not believe that they are built as 
accurately as you describe. Just measure a few Hamburg action 
hammer/key ratios to confirm this for yourself.

A part-image of an action, with an accompanying formula for 
calculating the hammer/key ratio can be found on our website at;

http://overspianos.com.au/anrt.html

I have followed some of this thread. The relationship between 
hammer/key ratio, hammer weight and required key leads is interesting 
regarding overall system inertia. Although the inertia effect of 
excessive key leads is well understood, a heavier hammer will have a 
similar effect to an excessive quantity of key lead. The practice of 
using many key weights to offset a poor combination of heavier 
hammers with a higher than appropriate hammer/key ratio, will make a 
poor situation worse.

Heavier hammers, just like adding more key leads, will result in 
extra action system inertia. Although the weight of a heavier hammer 
might seem moderate when compared to the use of an extra key lead, 
the effect of each extra gram of hammer weight must be multiplied by 
hammer/key ratio. A one gram heavier hammer will increase the down 
weight by 5.5 grams if the hammer/key ratio is 5.5:1. The inertia 
effect from hammer weight can be similar to that of adding key leads. 
To the pianist, the feeling of inertia will be the same, no matter 
what the cause.

Over the years, we have learned almost to predict the hammer/key 
ratio range of an action by the overall weight of the keyboard and 
action, when pulling it out of the piano for repair. There is a 
preponderance of high ratio/heavy hammered instruments out there, 
with disastrous quantities of lead, inserted in a vain attempt to 
make them playable.

Dale, I saw your post this morning when you wrote the following:

At 4:28 PM -0400 13/7/02, Erwinspiano@AOL.COM wrote:
>  I'm working with a 1920 Baldwin 5 ft. 8 inch grand that proves the 
>point. Keys are full of lead in the bass with 4 leads still at note 
>40. Horribly heavy static touch weight ,70-80 grams
>      I moved the capstans 3/8 of an inch to try to overcome the key 
>leverage and match the only  choice of shank and wippen for this odd 
>beast available and I still had to shoot for low hammer /strike 
>weights. Note 4 needed no more than  8 grams ,note 16- 7.5 grams 
>note 40-6.5 grms ,you get the idea.  Even at this I'll only be able 
>to remove 1 or possibly 2 leads in the bass. (7-8 per key)
>     The true fix would be new keys and leverages to match the parts 
>available which wasn't an option in this case. I tried.
>    It will work but I've never moved capstans that far. Wow!

Some of the grand pianos from that era typically had hammer/key 
ratios as high as 8.0:1 with light hammers. I'd be very interested to 
know what the measured hammer/key ratio is for the Baldwin you 
describe. even after you moved the capstan 3/8". The fact that you 
still needed many key leads with such light hammers to achieve an 
acceptable down weight, would lead me to suspect that the ratio 
remains relatively high. If you still have the piano in your 
workshop, I'd be interested in the figures.

Regards,
Ron O.
-- 
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OVERS PIANOS - SYDNEY
Grand Piano Manufacturers

Web: http://overspianos.com.au
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