Yamaha Spring Tension

[Thomas Cole]

Jon,

I like this approach. Not only are you replacing the cords, but the 
action is getting some upgrading (repinning, hammer shaping, etc.) while 
you have the parts on the bench. Very efficient and thorough and the 
customer can notice the difference.

One addendum to my procedure since you mention it: you either have to 
make a 9/16" dowel, if you have a lathe, to get your 44 mm cord lengths, 
or you can wrap cord around a piece of wood that's, say, 17 mm x 5 mm (x 
whatever length) to get that same "circumference."

I've never measured the spring tension but have just eyeballed the 
position of the springs in their relaxed state for fairly even pressure 
on the cords, and mostly straightening any bent ones.  I'll be taking 
readings on the next job, though. Thanks.

Best,
Tom Cole


Jon Page wrote:

> > 40 grams measured at the spring is roughly
> >equivalent to 20 grams measured at the flange.
>
> Thanks Frank, that's what I'm getting when I open the spring
> so as to have the arms in line at 180 degrees (the resulting
> angle is around 130 degrees) and attach to the loop.
>
> I'll enter this info into my Action Handbook in the Yamaha section
> along with 44mm cord length which is achieved by wrapping the
> cord around a 9/16" dowel and slicing along the length of the dowel.
> Glueing cord ends onto the flange 10mm on each side of the yoke.
>
> I remove the hammers/flanges from the rail, number each and separate.
> This way I can file the hammers on the oscillating spindle sander and
> decide if repinning is in order. Secure the flanges in a vise to clean the
> flange grooves and install the new cord. Assemble units, open spring, 
> hook.
>
> I might even opt to taper the hammers slightly. RIght side in the bass,
> left side in the tenor and both sides in the treble.
>
> Tom Cole's procedure is here (see photo at end):
> https://www.moypiano.com/ptg/pianotech.php/2006-December/198869.html
>
>-- 
>  
>
>
> Regards,
>
> Jon Page

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