need ideas (more)

[Greg Newell]

Keith,
    I guess it didn't sink in earlier that this was an older Yamaha. It doesn't
surprise me nearly as much now as I recall that they were built much "lighter"
back then. I remember someone telling me that they were built with fewer (or in
some cases none) backposts because they were built so well that they really
didn't need them anyway. Being one who often can wear his emotions on his sleve
I couldn't hold back a smirk, but that's another story. I'm thinking your idea
is a good one but perhaps if you have an engineering program there it could be
run past them to see if perhaps a different placement of post supports might be
even more beneficial.
Cheers!

Greg

kam544@flash.net wrote:

> Susan, Mark, Greg, Jon, Newton, CAUT,
>
> Some additional info:
>
> These particular pianos roll quite easily with the existing casters, though
> the idea of using a different dolly system would change the potential
> 'racking' (assuming this means twisting?) by the different location of the
> wheels.
>
> However, it just so happens there is a 1971 U1 in a classroom across the
> hall that has been here since new and one I don't ever recall having this
> type problem.
>
> So, I decided to compare the structure of it against a 1998 U1 that does
> exhibit this problem.  I came up with some interesting dimensional numbers
> plus a potential cure for this tuning instability as a result of doing this.
>
> Here's what I found:
>
> 1) The five back posts are not the same.
>         1971 U1  3  9/16" D x 2  5/8" W
>         1998 U1  2  9/16" D x 2  5/8" W
>
> 2) The handhold devices in the rear for moving the piano are married
> (joined) to the 2nd back post inward from the left and right back post on
> the 1971 U1.  On the 1998 U1 that does not occur.
>
> 3) The 1998 U1 has what I guess is called a full perimeter plate.  The 1971
> U1 does not.
>
> 4) The cabinet sides, front to back are 7/8" longer on the 1971 U1 and are
> thicker by 1/8" more.
>
> 5) The feet of the 1971 U1 are 3/8" wider.
>
> By my measurements, observations and extrapolating, there is definitely
> less wood in the back posts, and feet, plus less support between the back
> posts due to the different handles.  Maybe the full perimeter was an idea
> that would compensate for this less wood, maybe not.
>
> Anyhow, here's the potential cure which I am going to implement upon
> approval from the Piano Chair.  I have used this following idea for sagging
> shelves that had no support, so my thinking says why not for back posts
> that have no support between themselves.
>
> I'm going to take three pieces of hard rock maple 1' x 4" x 57 1/4", locate
> them evenly spaced from top to bottom and join the five back posts
> together.  I feel confident this will make a remarkable change in the
> stability.
>
> Still open to any other constructive ideas that someone might have, or ones
> that someone has possibly implemented and had success.
>
> Thank you all for being a sounding board  :-)
>
> It is greatly appreciated!
>
> Keith McGavern, RPT
> Oklahoma Baptist University
> Saint Gregory's University
> Shawnee, Oklahoma, USA

--
Greg Newell
Greg's Piano Forté
12970 Harlon Ave.
Lakewood, Ohio 44107
216-226-3791
mailto:gnewell@ameritech.net