[pianotech] Jack Springs

[John Ross]

That is what I was looking for, some information.
That other design, was a real mess to untangle, the strip of masking  
tape helped.
John Ross,
Windsor, Nova Scotia
On 11-Mar-10, at 6:18 PM, Ron Nossaman wrote:

> John Ross wrote:
> It is from Schaff, item number 527A, upright jack spring.
>> The physical properties are equal taper from top and bottom, to a  
>> compacting of a couple of coils, in the centre, like each end.
>> The old springs were a double at each end, and the winding went  
>> wider in the middle.
>
> John,
> I haven't used any of these yet, but there was a Journal article  
> (don't know when) on how the design was arrived at. There's less  
> torsion stress on the wire because there are more coils within the  
> compression range, pretty much eliminating breakage and producing a  
> more constant spring rate, and they don't tangle into one giant  
> permanent spring in the bag. I don't see a reason they'd be noisy,  
> but I don't really know. I'd try them.
> Ron N