Hammer Weights?

[David C. Stanwood]

Dear Bill,

I've seen technicians weigh keys and/or sacrifice hammer weights to fix
heavy action when all along the problem was simply tight key bushings.  I
suspect that this is the cause of your problem as your touch weight numbers
indicate high friction and work was done to the key tops.  Quite often key
bushings are replaced with this kind of work... Do you know the friction
formula?  Friction Weight, the amount of weight to overcome friction in the
slowly moving key, is found as (DownWt - UpWt)/2.  In your case of note C5
for example, the friction weight is 21 grams.  It should be more like 13
grams...  Easing and lubrication with teflon powder or spray is in order.
Then play the piano and dedide if more radical work is in order.

You can measure and rate key bushing friction as follows:

Remove the stack and set it aside.  Place a weight on the back of  key
sufficient to hold the key down on the back rail.   A key leveling lead
works nicely or jiffy leads on the back side of the key.   (The amount of
weight is not important so long as the key sits down on the back rail.)
Measure Up and Down Weight of just the keystick and plug the numbers into
the formula for Friction Weight, (DownWt - UpWt)/2.  

Keystick friction weight may be rated as follows:  

Low = 1 - 3 grams,  Medium = 3 - 6 grams, high = above 6 grams.

Don't feel bad.  Tight key bushings are overlooked even by well experienced
techs and dealers.

David Stanwood

P.S. - 1 quarter = 5.7 grams so your down weight on C3 is 81 with an Up of
16 that's a  32.5 Friction!
I've posted a friction rating chart at:
http://www.stanwoodpiano.com/touchweight.htm

>Hre are my measurements.  My grams weights only go to 64 grams so I
>added quarters (I don't know the weight of the quarters but I think you
>will get the idea.)
>C2 up 28 grams down 64+3 quarters
>C3 up 16 grams down 64+3 quarters
>C4 up 24 grams down 64+1 quarter
>C5 up 22 grams down 64 grams
>C6 up 32 grams down 64+3 quarters
>
>The reason I believe it's the hammers is I remember this piano from
>before and it played nicely.  It then had new key tops and new hammers,
>shanks, and flanges probably a couple of years ago.  Now nobody wants to
>play it now because it is so hard to play.  I was thinking of shaving
>the hammers before I went out and replaced them.
>
>Thank you
>Bill