[pianotech] Wandering Capstan Screws

[David Skolnik]

DavidB says:
>Another possibility, of course, is that Dr or Mrs C are somnambulists, and
>creep into the room in a somnolent state in the dead of night with a
>screwdriver.....

Should be easy enough to confirm, with the able assistance of one or 
two talented former employees of News Of the World, eh?

Otherwise, I'm not sure you understood what I was proposing regarding 
the hammer rail, but it can wait until you have a chance to revisit 
the instrument.

David Skolnik
Hastings on Hudson, NY




At 03:33 PM 12/6/2011, you wrote:
>Hi DavidS,
>
>Thanks for those additional observations.
>
>There is not a new problem due to recent renovations.  I have been tuning
>this piano since nineteen eighty-eight and it has always done this, and
>changing the capstan screws for thicker (therefore tighter) ones did not
>change it.
>
>If the hammer rest rail, or the back rail in the keybed, were warping
>seasonally or cyclically, the hammers could not lift (and fall) so
>unevenly, could they?
>
>What is happening has got to be a function of the capstan/felt/sticker
>interface for each key, as far as I can see. Either because, as Wim
>suggests, the rectangles of felt covering the capstan screws are swelling
>and shrinking to an extraordinary degree and unevely, with changes in
>humidity in the room, or because as Ron suggests, some shifting movement
>is altering the position of indentations in the felt over the head of the
>capstan screws.
>
>I will be returning to tune the piano  soon, when the room redecoration is
>complete, and at that time I will examine very carefully the undersides of
>some of the pieces of felt. I will endeavour to take photographs then.
>
>Another possibility, of course, is that Dr or Mrs C are somnambulists, and
>creep into the room in a somnolent state in the dead of night with a
>screwdriver.....
>
>Best regards,
>
>David
>www.davideboyce.co.uk
>
>
> > DavidB -
> >
> > Some concurring or additional observations:
> > If the screws were loose, it's unlikely that they would move
> > counterclockwise, to lift the hammers from the rail.
> > The cloth on the rail is old (look at indentations in picture
> > 3).  The indentations do not look even and the cloth likely has no
> > resilience left. DavidB says:
> >>So I regulated the screws back down, leaving the hammers on the
> >>rail, without lost motion
> > which means it's possible, if not likely, that the distribution of
> > weight between 'capstan' and rail was inconsistent, all the more so
> > because of the nature of this type of  hammer rail, which would seem
> > to limit, if not preclude, the technique of pulling back on the rail
> > to gauge the degree of hammer-follow.  There's too much potential for
> > inconsistency here to derive a grand (or upright) unifying
> > theory.  BUT WAIT! THERE'S MORE!
> >
> > As Wim points out, there have been a series of renovations to the
> > space that could have allowed the introduction of significant
> > variations in temperature and humidity, and he also makes reference
> > to new carpeting being, or soon to be installed.  The piano, is
> > seems, is getting moved around.  Any variation in the way an upright
> > sits on the floor can cause a change in the way it flexes, affecting
> > both tuning and regulation.
> >
> > Wim suggests waiting until renovation work is done, which is a lot
> > more reasonable than my alternative:   A new piano AND a new house.
> >
> > Good luck
> > David Skolnik
> > Hastings on Hudson, NY
> >
> >
> >
> > At 03:51 AM 12/6/2011, you wrote:
> >>David
> >>
> >>The first question: The round sticker w/cloth against the round
> >>capstan. That is the ideal situation. The two round surfaces work
> >>very well together, without creating any friction.
> >>The other question/concern, about the screw moving. I don't
> >>understand how a screw could turn in the wood, unless it was loose
> >>enough that it could be turned by you fingers. There is nothing on
> >>the felt that would be able to turn it.
> >>
> >>You mentioned new carpets and new windows. Have these people been
> >>doing lot of renovating in the house? New carpets give off a lot of
> >>moisture. New windows mean there is a lot of moisture coming in the
> >>house while they are replacing them. Any painting going on near the
> >>piano? All of those things will create a lot of swings in humidity
> >>and temperature.
> >>
> >>If there is a lot of renovating going on, perhaps you need to ask
> >>the customer when all the work will be done. Then, when the house is
> >>stable, check the hammer line again.
> >>
> >>Wim
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>-----Original Message-----
> >>From: david <david at piano.plus.com>
> >>To: pianotech <pianotech at ptg.org>
> >>Sent: Mon, Dec 5, 2011 11:23 am
> >>Subject: Re: [pianotech] Wandering Capstan Screws
> >>
> >>Thanks for those further thoughts, folks.
> >>
> >>I made a silly mistake, wasn't thinking (am on a course just now and it's
> >>quite intensive).  The piano action DOES have stickers.
> >>
> >>Thinking then about putting action cloth on the ends of the stickers, and
> >>replacing the screws with capstans:
> >>
> >>Might there be a concern about the two curved profiles? Would the
> >>relatively narrow-radius curve of the now action-cloth-clad sticker ends,
> >>bear OK, and be stable enough, against the radius of the capstan surface?
> >>
> >>I am still kinda feeling that the blue felt on top of the capstan screws
> >>can't be swelling THAT much, to cause all that lifting. Could the wood of
> >>the keystick be of some particularly "soapy" variety, that shoves the
> >>screw threads around, with cyclical changes in humidity?
> >>
> >>With regard to humidity changes, I have wondered for a while if there is
> >>some cyclical change going on in that room even thought it doeosn't feel
> >>damp.  The answer, I think, is yes.  The room, a study/spare bedroom is
> >>just across a corridor from the kitchen, and very near the back door. It
> >>is quite possible that there could regularly be brief bursts of
> >>moisture-laden air, which then gets cleared in some way, but in the
> >>meantime has condensed inside the piano.
> >>
> >>An additional factor at the moment is recent replacement of the windows,
> >>which meant the room was cold and damp for a day or two.
> >>
> >>But its still an intriguing question as to whether the screws move.
> >>
> >>I will be returning soon to tune the piano (my recent visit was just to
> >>check out a problem following the window replacement - the half-blow
> >> pedal
> >>rod had become dislodged) and I suggested leaving the tuning until the
> >> new
> >>carpet was laid and the piano placed where it's to go in the room.
> >>
> >>I will check out the undersides of the blue felt and see how
> >>dimpled/ridged they are.  If I don't replace the screws with capstans,
> >>then I will mark them and the keystick, and see if there is any
> >> movemment.
> >>
> >>It occurs to me also to suggest a Dampp Chaser, so that if there is a
> >>sudden surge of moisture-laden air into the room from the kitchen, it
> >>can't condense in the piano.
> >>
> >>Best regards,
> >>
> >>David
> >><http://www.davidboyce.co.uk/>www.davidboyce.co.uk
> >>
> >
> >