[pianotech] Square Grand Jack Springs and Cords

[Joseph Garrett]

Terry,
The proper tension is critical! I've found that, if the jack is about 30-45
degrees when the slack comes out of the cord and the spring engages, will
give you optimum repetition, (such as it is<G>). If there is too much
tension on the springs, or not enough the repetiton goes south. Not enough
and the jack won't reset under the butt notch. Too much and the jack jams
against the face of the butt notch. BTW, there needs to be "just" a slight
bit of lost motion, so that the jack can reset. Have you drilled out the
let-off rail for access to the rocker capstan screws? You HAVE to, to save
yourself a whole lot of grief!
Joe


> [Original Message]
> From: Terry Farrell <mfarrel2 at tampabay.rr.com>
> To: <joegarrett at earthlink.net>; <pianotech at ptg.org>
> Date: 5/29/2012 6:53:01 PM
> Subject: Re: [pianotech] Square Grand Jack Springs and Cords
>
> What is the proper tension setting on the spring - i.e. should the jack
be parallel with the base with no slack in the string, or should there be
some slack - and if so, how much?
>
> Currently, most of the jacks on this piano will raise about 20 degrees or
so from horizontal before the spring is engaged.
>
> Thanks for your input Joe.
>
> Terry Farrell
>
> On May 29, 2012, at 9:46 PM, Joseph Garrett wrote:
>
> > Terry said:
> > "Is there a source for square grand jack springs? I don't have any
broken
> > ones on this 1867 S&S square that I am working one, but seems to me
that as
> > long as I'm replacing the cords, I might as well replace the springs.
Seems
> > I recall running across some broken ones years ago on other squares.
Very
> > thin metal springs - certainly 147 years is enough for them to have
> > deteriorated a bit.
> > 
> > Yes? No?
> > 
> > Source?
> > 
> > Get out the spring-making tool?"
> > 
> > Terry ,
> > Do the cords and leave the springs alone. There is little stress on
them,
> > for the most part. However when you have a broken one, it's time to
> > replace...JUST the broken one, imo. I have some spring stock that is a
> > close facimile of the originals. It is not for sale, as the original
> > company that made it, although still in business, does not make it
anymore.
> > They would make some if I wanted to commit to about 5 miles of the
stuff!
> > It is hard to find, if at all, so go with the: If it ain't busted, don't
> > fix it" Thang.<G> As for getting out the spring-making tool, Rotsa Ruck
> > Dude! BTW, there are a few different configurations of those jack
springs
> > set-ups.. just so's ya know. The type that does not have the cords, is
most
> > prone to break and is the most difficult to fix!<G>
> > Regards,
> > Joe
> > 
> > 
> > 
> > Joe Garrett, R.P.T.
> > Captain of the Tool Police
> > Squares R I
> >