Interesting H.F.Miller Upright

[Delwin D Fandrich]

----- Original Message -----
From: <PNOTNR@AOL.COM>
To: <pianotech@ptg.org>
Sent: March 25, 2000 5:27 AM
Subject: Re: Interesting H.F.Miller Upright


> Thanks Del,
>
> I had considered, ask you said  in your response, that the scale designers
> might not have known what thay were up to.
>
> Using the scaling software I have, I've been able to improve the scale a
lot,
> but it would call for a substantial increase in tension (32,000 lbs. to
> 35,500 lbs.)  Is there a way to determine whether a plate can take the
> additional stress?
>
> I also have a redesigned scale for this piano (from another Pianotech
> subscriber) that makes an improvement over the original, and only changes
the
> tension about 200 lbs, but doesn't look as good (on paper) as mine,
according
> to the sofware's suggested inharmonosity curve.
>
> Thanks,
>
> Gordon
>
-----------------------------------------------

Gordon,

Way too much importance is placed on that inharmonicity curve.  You aren't
really going to hear inharmonicity.  Well, you might be aware of it since
you are going to be tuning the piano, but it is not something the pianist is
going to be bothered by much.

Those lines on the scale chart are arbitrary and you have my permission to
ignore them.  I do it all the time.  In fact, most of my new scales have
some areas where they fall outside of those lines.

Worry about things like overall tension -- don't raise it significantly from
the original.  Usually you can raise it a bit in the high treble and the
very low tenor.  Try to compensate somewhere else, like in the upper bass,
so that you don't raise the overall tension much -- if at all.  Nothing
catastrophic has never happened to me but I always worry about the overall
load on the plate and only increase it with great caution and then only when
I can personally examine the piano and the plate.  One or two percent is
probably never going to cause a problem.  Ten percent would raise my
eyebrows. Anything more than that would send me out of the room when the
piano is pulled to pitch unless I was really sure about the plate.

Having said all that, 32,000 lbs. (14.4 kgs.) is fairly low for a 'modern'
upright piano scale.  Look at the plate and try to figure out where its
weaknesses are.  Where will it break if you put excessive tension on the
stringing scale?  Where is that tension going?  Are you adding it to just
the upper tenor/treble section (where most plates are reasonably
over-designed)?  Or are you adding it to the low tenor/upper bass (where
most of them are marginal)?

There is no short answer here.  It takes a lot of experience and thoughtful
consideration to begin to make these judgments.  It is a lot like tuning or
voicing.  You aren't going to learn much about it until you wade in and
start doing it.

But don't just slap that new scale on there.  Stare at the plate for a
while.  Examine the cross-section shape of the plate struts.  Check the
thickness of the plate panels -- both the hitchpin panel and the tuning pin
panel.  Look to see how the plate is tied down.  (It has always puzzled me
why some builders would put umpty-dozen huge lag screws and/or bolts through
the plate up around the tuning pin field and four or five wood screws
through the bottom rail of the plate.

Anyway, as I said, there is no easy way to make these decisions.  Start with
the piano you have in front of you and study it from the perspective of what
makes it tick and what will make it break.

Good luck,

Del
Delwin D Fandrich
Piano Designer & Builder
Hoquiam, Washington  USA
E.mail:  pianobuilders@olynet.com
Web Site:  http://pianobuilders.olynet.com/