Capo Hardening, was: Tuning problems under capo bar

[Farrell]

Hello Ron. I there anything you can tell us about hardening the capo. I've seen you write about that before. Is this something you do in your shop? Do you do it to all pianos? Do you have a method of testing the hardness of the capo? Am I asking questions that have already been answered? Thanks.

Terry Farrell
  
----- Original Message ----- 
From: "Ron Overs" <sec@overspianos.com.au>
To: "Pianotech" <pianotech@ptg.org>
Sent: Friday, January 24, 2003 6:03 PM
Subject: Re: Tuning problems under capo bar


> At 5:02 PM +0100 24/1/03, Michael Gebhardt wrote:
> 
> >I've recently started to teach myself piano tuning. During
> >Christmas holidays, I've had an opportunity to tune my
> >parent's piano (1980 Hamburg Steinway A). I've noticed the
> >following problem:
> >
> >When I tune the strings that pass under the capo bar,
> >nothing happens at first, and as I continue to turn the
> >lever, the pitch suddenly "jumps" far beyond the point
> >where I want to get it as soon as friction in the contact
> >point with the capo bar is overcome.
> 
> What you describe is a typical symptom of a Capo' which has developed 
> excessive friction, due to deformation which has occurred when the 
> soft iron bar has been cut by the piano wire. In 1980, Steinway were 
> doing nothing to the bar. Not only was the shape of the bar pretty 
> ordinary, but the cast iron was extremely soft.
> 
> Today, Steinway Hamburg are treating the bar to increase its hardness 
> (I have heard reports of them using a laser beam for heat treatment). 
> Unfortunately, the hardness level remains inadequate since even their 
> latest outpourings develop string grooves (and noise) in a very short 
> time.
> 
> >In order to get a smoother change, I had to strike the note
> >several times VERY firmly after each slight turn of the
> >pin, to equalize string tension.
> 
> Indeed, your  parent's piano requires a restring and the bars need to 
> be reshaped and hardened. Its just a waste of time trying to tune an 
> instrument with this problem, since it'll be 'screaming' before the 
> ink is dry on the cheque.
> 
> Furthermore, if you decide to restring the piano (if you are a novice 
> I would recommend, at the very least, that you undertake the work 
> under the supervision of someone who is an experienced rebuilder) the 
> lengths of the front duplex segments should be checked against the 
> speaking lengths. If string noise is to be minimised (you won't 
> eliminate it on a Steinway because the duplex lengths are far too 
> long), the each duplex length should not divide equally into its 
> adjacent speaking length (if the segments are in tune, you can move 
> the duplex bar apex one way or the other to detune it when the bar is 
> reshaped). Below is a web link to an image of a Yamaha G2 duplex 
> system which we detuned during the reshaping and hardening process;
> 
> http://overspianos.com.au/g2fdp.jpeg
> 
> Steinway and Yamaha try to make the duplex lengths tuned, and while 
> Yamaha do a pretty job of it, the practice is in my experience a 
> design ideal which should fail to be one as soon as possible.
> 
> Check out the list archives. Much has been written on this topic. A 
> number of varying opinions have been offered. You'll just have to try 
> a few things for yourself and think about the outcome to work out 
> who's on the money.
> 
> Regards,
> Ron O.
> -- 
> _______________________
> 
> OVERS PIANOS - SYDNEY
> Grand Piano Manufacturers
> 
> Web: http://overspianos.com.au
> mailto:info@overspianos.com.au
> _______________________