Loose Plate bolts, Baldwin SD-10

[Jim]

Hi Warren:

Tightening the perimeter plate bolts in an SD10 with the patented plate
support system would not change the plate height.  Are you sure it was an
SD10?  The Plate is threaded. When bolts are installed in the SD10, as the
bolts screw down through the plate, when they reach the soundboard and
inner rim, they make their own threads.  These are long bolts.  There is
nothing that tightening the bolts can do to change the number of threads
per inch between the bottom of the plate and the top of the soundboard.
Tightening the bolts only makes sure that the washer under the bolt head
is not loose. It does not change the plate height.  Now if someone rebuilt
an older SD6 and put the SD10 letters in the well, that's a different
story.  With a mirror down thru the plate lightening holes if you can see
that the plate bolts have threads just underneath the plate, it is a
standard SD10 plate suspension system. You also will not find support
dowels under the plate. In that case, you really didn't
change the plate height.  You just may not have noticed it before you
tightened the bolts. I just can't imagine that you stripped out the
threads of the plate during a tightening process. These are 1/2 inch
bolts.

Jim Coleman, Sr.

On Mon, 14 Apr 1997, Warren Fisher wrote:

> While tightening bolts on an SD-10, I found 3 in a row that were very
> loose so I tightened them snugly but I didn't crunch them.  When I sat
> down to start tuning and happened to glance at the three bolts, to my
> horror I saw that the area of the plate under those bolts was no longer
> straight, but had dipped lower between 1/8 to 1/4 inch?  I really didn't
> measure it because I immediately loosened those bolts again to
> approximately the way they were before!
>
> What's going on here?  Should they be tightened anyway?  I know I should
> jerk that plate out of there and replace the plate supports, but this is
> a church, I don't think they'll buy it.  Should they be left a little
> more than hand-tight, or what?
>
> The bolts are located just forward (toward the keys) of the massive
> delta shaped plate bracing that supports the back of the plate where the
> bass bridge is.
>
> Any help will be greatly appreciated,
>
> Warren
> --
> Home of The Humor List
> Warren D. Fisher
> fish@communique.net
> Registered Piano Technician
> Piano Technicians Guild
> New Orleans Chapter 701
>