20 tons of tension

[Jim Coleman, Sr.]

Hi Roger:

The Knight piano has a full perimeter plate and its sustain quality was
greatly improved over all other vertical pianos.

Jim Coleman, Sr.

On Wed, 26 Aug 1998, Roger Jolly wrote:

> Hi Clyde,
>           Plate design has come a long way since the post war years, the
> average manufacturer has done more with stress analysist. The Schimmel if I
> recall has what is termed a full perimeter plate. In other words the outer
> struts or webbing form a box, this prevents trapezium distortion from the
> in balance of tension due to the cross stringing, but is a cheaper design.
> A little more cast iron and no back support. now the draw back. The centre
> of gravity has moved back  closer to the rear edge, in a school setting
> there is a danger that the piano can easily be flipped over. The other
> disadvantage is that the  soundboard liner does not have the same kind of
> support as in the more conventional method of manufacture. MY gut instinct
> makes me think long term stability may be an issue.
>  Most of the tension is taken by the plate in all designs, depending on the
> ductility of the cast, rigidity and placement of plate webs ect. will
> determine the need for back post, the material used, cross sectional area
> and placement. Getting back to the liner and back assy. the average piano
> has to bear 1000-1500lbs of down bearing pressure, the sound board is
> carrying this load and this is where the liner and back support really
> comes into play,as it keeps the perimeter of the board more rigid if well
> designed, therefore reflecting more energy back to the centre of the board,
> many of the full perimeter plate designs that I have listened to have only
> so so sustain qualities. This could be overcome with hard maple or beach
> liners, but is not usually the case. You have opened a real can of worms
> with this question, so now I will don a flame suit.
> Roger
> 
> 
> 
> At 10:54 PM 25/08/98 -0400, you wrote:
> >Friends:
> >
> >As I was tuning a late model Schimmel studio piano today I noticed it
> >had no back posts, really no back at all that I could see, other than
> >the soundboard and ribs.
> >
> >Which got me to wondering -- how much of the 20 tons of tension is
> >usually on the back and how much is on the plate?  Only once before did
> >I see a vertical piano without back posts, an old upright.  I also
> >remember about 20 years ago a salesman pointing out the rather thick
> >back posts on Everett studio pianos as an indication of their high
> >quality (I knew much less about pianos then than I do now).  How
> >important are those posts really?
> >
> >Clyde Hollinger (who is getting tired of adding RPT Lititz PA)
> >
> >
> Roger Jolly
> Baldwin Yamaha Piano Centre
> Saskatoon and Regina
> Saskatchewan, Canada.
> 306-665-0213
> Fax 652-0505
>