The "Jolly Loop" (Modified by Kent Swafford)

[Roger Jolly]

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At 11:34 PM 4/8/2005, you wrote:
>
>
>
>----------
>From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On 
>Behalf Of Roger Jolly
>Sent: April 08, 2005 2:18 PM
>To: Pianotech
>Subject: RE: The "Jolly Loop" (Modified by Kent Swafford)
>
>Hi Del
>               I have too much evidence to the contrary.  The end of the 
> knot becomes a theoretical termination point, and the helix is almost 
> incapable of flexing.
>
>I'd sure like to see it. With vertical hitches the string doesn't have to 
>flex, it pivots at the hitchpin itself. The twist is of no consequence.

A very interesting hypothesis.   We may as well stop calculating 
inharmonicity,  on the bare section of core wire, in the speaking 
length.  Or is that also of no consequence?   Is the stiffness of the swage 
also of no consequence?
The hitch termination has an effect on the control of bearing and is indeed 
a great asset in design.  However when you double the thickness of the wire 
over about 50% of the back scale length and mass load it with 3-4 complete 
turns at the end of the knot. It sure as heck as an effect on the 
flexibility of the back scale.

>
>
>  So many pianos have about a 55mm knot at A0,  and only about 7-10mm of 
> flexible string.  James had a clear demonstration model at the Cal state 
> convention.  The reaction of all that saw it was wow! The vibration time 
> of the new knot vs an English loop is about 3 times greater.
>
>I can see this if it is compared to a conventional hitchpin system. But 
>not if it is compared to a vertical hitchpin system.

It is the bridge that sets the back scale in motion.  Bearing and back 
scale flexibility interact, and has a profound effect on how the bridge is 
going to react..   You are trying to say that the stiffness of the helix 
and mass loading of the knot has no effect on flexibility?    Plucking the 
back scale of the small Walter's grand still sounds fairly dead to me.  And 
that is a fair clue to a stiff back scale.


>
>To the previous writer, it is not Del's hitch pins.  But was developed and 
>patented by Harold Conklin of the Baldwin piano company.
>
>The vertical hitch pin that I most often use is some different than that 
>used by Baldwin. It is this difference the writer was referring to not the 
>invention of the system.
>
>And, for what it's worth (and with respect to Mr Conklin's many other 
>achievements), when I was at Baldwin I was told by both Bob Cutshall (then 
>head of engineering) and Bob Farris (then chief piano engineer) that the 
>actual inventor of the vertical hitch and the floating plate mounting 
>system was a piano technician/rebuilder who worked in the R&D shop.

I was lead to believe the patent reads H. Conklin and the Baldwin Piano 
Company.   I guess I am corrected?

Regards Roger

>
>Regards,
>
>Del

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