[pianotech] bass strings installation

[David Love]

Just one quick note, it doesn't matter which end you are viewing the string
from when it comes to turning it clockwise or counter clockwise.  If the
string is to be twisted counter clockwise it will be that way when viewed
from either end.  

David Love
www.davidlovepianos.com


-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Ron Overs
Sent: Thursday, April 23, 2009 5:21 PM
To: pianotech at ptg.org
Subject: Re: [pianotech] bass strings installation

JD,

Thanks for contributing this post.

Please read JD's post everyone if you're unsure about

For Australian made strings the twist is 
anticlockwise when viewing the wire from the 
hitch pin end. On Yamaha and Kawai the twist is 
clockwise. The direction depends on the end from 
which the string-winder starts to wrap.

This is a most important step and cannot be 
passed over without dire tonal consequences over 
the longer term.

One other point I would like to add is that the 
amount of twist which the copper inflicts upon 
the core when it is taken off the winding machine 
will vary considerably in response to the overall 
string length and the combination of core and 
cover diameters. Ideally, the amount of 
installation twist should be the equivalent of 
the twist which is put into the core wire when 
the string is removed from the winding machine.

For our 225 piano we asked our string winder, Lou 
Parke, to record the twist on each wire as it 
came of his machine, so that we could twist the 
strings to their optimum number of turns when 
installing them. Note also that the string, when 
at pitch, will have less twist than that which 
you put into the string when you install it. The 
reason for this is that when the coil is being 
formed, as the string comes up to pitch, there is 
considerable wire deformation going on at the 
tangent where the wire meets the tuning pin. The 
torque from the twisted wire will tend to 
encourage the core wire to untwist the core as it 
wraps around to tuning pin. So in end the twist 
in the core will be something less than that 
which we put into before placing the eye on the 
hitch.

Ron O.



>At 15:34 -0500 23/4/09, Porritt, David wrote:
>
>>I generally don't twist bass strings.  If I 
>>install one and it sounds like it needs a twist 
>>I'll do it, that of course makes an extra step 
>>but if I had very many that need twisting, I'd 
>>contemplate a different string maker.  I think 
>>well made bass strings shouldn't need twisting.
>
>It's not as simple as that.
>
>It is true that with certain special exceptions, 
>which I won't go into, a well made string will 
>not buzz or sound bad if you don't twist it, 
>but, as I've explained at least twice before on 
>this list of very short memories, if you do not 
>twist the string then you are putting on twisted 
>strings, and twisted in the wrong direction at 
>that.
>
>There may be one or two over-enthusiastic 
>stringmakers in the world who pre-twist the 
>steel core on the machine before winding, but it 
>is a rather pointless exercise in a market that 
>generally speaking has learned to twist covered 
>strings on installation.
>
>When the steel core is hitched to the pin end of 
>the machine, clamped in the chuck end and 
>tensioned, it is, of course in equilibrium, not 
>twisted.  The copper is then wound on to the 
>steel, and this copper is held under tension 
>during its whole journey from the flattening at 
>one end to the flattening at the other.  It is 
>therefore exerting a twisting force on the core 
>wire.
>
>The wire cannot twist while it is clamped in the 
>chuck, but as soon as the string is released 
>from the machine, the copper will release as 
>much of its stress as it can by twisting the 
>core wire.  The degree to which it will twist 
>the core is dependent on the thickness of the 
>core and the amount of stress in the copper. 
>There are extreme cases (which I said I wouldn't 
>go into!) where, even though the stringmaker has 
>applied the proper maximum tension to the copper 
>during winding, the thinness of the core 
>combined with a heavy cover exerting a strong 
>twisting force leads to too great a release of 
>tension in the copper, accompanied by 
>considerable twisting of the core, and the 
>result is that the string will actually buzz if 
>it is not twisted on installation.  Several 
>Blüthner models have such strings, but they are 
>rare.
>
>There is a limit to the tension the stringmaker 
>can give to the copper, because, in the case of 
>thin copper the copper will break and in the 
>case of thin cores and heavy covers, the eye or 
>the chucked end will break.  The stringmaker 
>learns from experience the maximum proper pull 
>for each combination.
>
>On the other hand the stringer is not so 
>limited.  What is simply not possible for the 
>stringmaker can be added by the stringer not 
>only to _restore_ but to _increase_ the tension 
>of the copper winding.  What _must_ be done is 
>to _restore_ the stringmaker's tension by 
>twisting the string say half a turn to undo the 
>twist it got when it left the machine, and what 
>is better is to increase the tension by twisting 
>yet more.  No matter what blessed stringmaker 
>made the strings, the sound will improve by 
>twisting them.
>
>
>To answer the original question, if the winding 
>goes like this ////// you twist clockwise and if 
>it goes like this \\\\\\ you twist 
>anti-clockwise.
>
>JD -- Stringmaker
>
>--
>______________________________________________________________________
>   Delacour Pianos  *  Silo  *  Deverel Farm  *  Milborne St. Andrew
>                      Dorset DT11 0HX  *  England
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