Tension Increase

[Roger Jolly]

Hi John,
             A semi tone will increase about 10lbs per string, as a very
rough rule of thumb.
So 220 strings will increase the overall tension about 1 ton.
Regards Roger




At 12:42 PM 04/01/00 -0400, you wrote:
>Hi John,
>I have successfully raised one of these "old Dominions", a semi-tone. It
>took it and held, not with just one tuning, though.
>I had been afraid of pinblock seperation, so I took the top off, and
>inspected it. The pinblock was attached to what looked like a piece of
>railroad track, which had bowed, giving the impression of seperation.
>I also would like to know what the added tension, would be in a situation
>like this.
>In the rural situation I am in, I frequently raise the pitch on the old ones
>I run into, a semitone, and even a tone or more. Only of course, if the
>situation warrents it. i.e. new owner with child taking lessons, or being
>played with other instruments. I always check for pinblock seperation first,
>and frequently replace the screws, with carriage bolts all the way through,
>to the back.
>Looking forward to seeing the answer.
>Regards,
>John M. Ross
>Windsor, Nova Scotia, Canada.
>----- Original Message -----
>From: "John Lillico, RPT" <staytuned@idirect.com>
>To: <pianotech@ptg.org>
>Sent: Tuesday, January 04, 2000 12:09 PM
>Subject: Tension Increase
>
>
>> If one raises pitch 1/2 tone to A440, how much tension is added to the
>frame, either in percentage or pounds?
>>
>> I successfully carried this out yesterday on a Dominion (circa 1910) which
>showed signs of structural weakness with the treble pin block having pulled
>slightly forward.
>>
>> Just wondered how much extra stress I had caused. Tuning is scheduled in
>four weeks.
>>
>> John Lillico, RPT,
>> Oakville, ON
>>
>>
>>
> 
Roger Jolly
Saskatoon, Canada.
306-665-0213
Fax 652-0505