[CAUT] Touchweight question

[Jim Busby]

Thanks David, Fred, Ric, others,

Yes, David, Danish it is. I will take measurements as you have suggested. I've already done some samples with a "normal" key leading pattern (w/o springs) and it works very "normal". I can't see why they did it the way they did. Now, with the Front Weight and Strike Weight in the "normal" range (SW needed no change, keys lots) I get very typical "good" DW and UW measurements (35-37 BW). That being said, if I do take advantage of the springs and eliminate some lead in the keys and let the spring do minimal work, as you suggested below, would that be "better" than with no spring at all? There is such a range here; from the original "make the springs do all the work" to no springs at all, and everything in between. Hence the query.

My limited understanding of the spring is that "if it is needed, then use it." And that seems to be for a larger piano, larger keys, etc. or if heavy hammers are used. If not, then why use them? I may then go to your "Cut 'em off" comment below.

BTW, the action ratio is 5.8. The spread is 113.5, so that doesn't seem to be the place. I thought about moving capstans.

There is so much to learn here! The bottom line, of course, is to make a piano feel great to the pianist. John Silverman's adviced to me a few months ago was "Don't try and make all pianos exactly the same! Vive le deference' (sp?) This project is almost a classroom to me.

Thanks for your help!

Regards,
Jim Busby



-----Original Message-----
From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of David C. Stanwood
Sent: Tuesday, September 23, 2008 6:33 PM
To: College and University Technicians
Subject: Re: [CAUT] Touchweight question

Jim,

Is this piano made in Denmark..?  Sounds more
like something a certain maker in Korea might
have done back then.   Disengage a few springs,
remeasure U/D then calculate the unsprung BW.
Compare this to the BW with the spring on and the
difference will tell you how hard the spring is
working.   9g - 11g is a conservative value and
will just support the weight of the wippen with
the stack on the bench with the hammers flipped
up.   17g would be an absolute limit not to be
exceeded without danger of creating a "Bouncy
Key" effect.


Support Springs aren't meant to fix a mismatch of
hammer weight and ratio that results in too much
lead in the key but rather a way of reducing lead
in an action that is already working ok thereby
making it a little lighter and faster on the
upstroke....

If you action balances nicely after removing the
back lead, disengaging the spring, and weighting
the keys normally with the lead weights in the
front then I would say Cut'em off!

David Stanwood



>All,
>
>I have an action (Hornung and Moller 1972) that
>has one or two leads in the very back of the key
>and no lead in the front. It has wippen helper
>springs. DW is around 65 - 70 and UW is around
> 36 - 40 or so. (Friction seems to be ok, but BW
>is 50 - 55!!)
>
>I don't know why the springs were adjusted for
>this weight, and I can adjust the springs to
>achieve a good weight (50-20 or so) but my
>question is a very basic one; Why would you use
>springs instead of leads to touchweight the
>action? What does this do to the MOI? Or, at the
>very least what is the difference in feel
>between a "spring" vs. "lead" touchweighted
>action? And, why do one over the other?
>
>Fred, Ric, enlighten me!
>
>Jim Busby
>
>P.s. I experimented and put weights in about 8
>keys and a normal leading pattern makes it
>workŠnormal.
>