Steinway Touchweight Problem

[David C. Stanwood]

Dear Stan,

The only way to tell the weight of a hammer is to weigh it.  The only way
I've found to weigh it on the shank is using a measurement I call Strike
Weight.  This is essentially tipping the hammer on a scale.

I've left you all a drawing of the setup for measuring Strike Weight at:

http://www.tiac.net/users/stanwood/swsetup.gif

Years of study have produced "Normal Zones".  I've left a graph of the
normal zones for all of you at:

http://www.tiac.net/users/stanwood/swranges.jpg

I would recommend what many technicians are doing which is to pick a strike
weight level that fits the existing action leverage (which varies alot from
piano to piano) and making the hammers conform to that specification.   If
your reducing weight this means taking whatever weight from the side of the
hammer that is needed to make the specification weight.  Some will need
less weight reduction than others because hammer weights tend to be jagged.
 Ideally you want to end up with a smooth curve.

There are many ways to lighten an action.

1. reduce friction
2. reduce hammer weight
3. reduce front weight (key lead weight) and and make up the difference
with wippen support springs.
4. increase leverage by:
	a. move capstan/heel line in towards balance rail.
	b. move knuckles further out on shank (watch geometry)
	c. move balance rail farther back (when having new keys made)

I would recommend the 17mm knuckle core to hammer center for teflon era
actions.
The originals were from 15.5mm to 16.0mm and they tend to be heavy.  It's
not the teflon,
it's the key ratios from that era.

David C. Stanwood

www.stanwoodtouch.com

>Subject: Steinway Touchweight Problem
>
>Hi, all!
>
>Problem:  Early 60's vintage Steinway 'L', with original teflon wippens and
>recently replaced (by someone else) shanks and flanges.  Parts are from
>Steinway and are 15 mm knuckle execution.  Downweight now in the high 60's,
>upweight in the high 20's, action weight in mid 40's and friction in high
>teens.  Action spread ranges from 113 to 114 mm.
>
>I have no way of knowing what size the original hammers were but tried a
>sample from a recent rebuild.  This admittedly well-worn Steinway hammer
>and shank was placed in its original location (A49) on my client's action
>and the touchweight came back to a more acceptable 52 (D) and 25 (U).
>
>The new hammers are noticeably larger than the old 'stand-in' and the tails
>are 3/16" longer (at drop position the bottom of the tails are about 3/16"
>below the tops of the backchecks).
>
>Am I correct in assuming I have excessive weight on the hammers?  Any
>wisdom in shortening the tails to correct the relationship of tail to
>backcheck?  The backchecks themselves appear to be new but it is difficult
>to know for sure.  They are considerably larger than the backcheck Renner
>includes in its sample parts kit.  Would an excessively large backcheck
>contribute appreciably to high action weight?
>
>Lots of questions here but the correct answers win a happy customer!
>
>Best regards,
>
>Stan Kroeker
>Registered Piano Technician
>