Positioning Plate/Action

[Meyer Carl]

mounting plates--here's a suggestion

Baldwin has a patent on threading the plate and suspending the plate on the
screws into the rim.  Probably worked good in the factory, but for
rebuilding I'm not so sure.

The best system I found was the mounting screws that Jim Coleman  sold that
consisted of a lag screw (1/2 inch) with a 3/8 inch allen set screw welded
into the head.

The reason I say that is because I like to give credit to those I steal my
ideas from.

I had a small grand piano that I was rebuilding and I wanted to use his
system.  Being cheap and in a hurry I tried to make some.  What a fiasco!
(Jeannie, I'm using the word properly this time).

It was a challenge to get the job done and meet my criteria of
simplicity,cheap and dam fool proof.

I came up with about three different procedures.

For this one I used a 3/8 threaded rod screwed into a shaft coupler (also
called a coupling nut).  At commercial hardware suppliers you can get these
(shaft couplers) with 3/8 on one end and 1/4 on the other.  I drilled out
and threaded the 1/4 end to 5/16.
Then I inserted a 5/16 set screw into the other end and locked them together
with locktite.  This particular piano had about one inch space between the
plate and sound board so it worked okay.  You need to select the length of
the set screw as required.  Now you need to bees wax the threads so that you
can adjust the depth (plate height) from above and then use a cap nut (also
called an acorn nut) from above.  Lockwashers (external tooth under the
plate and flat above the plate) and you have full adjustment without ever
removing the plate.

For other situations you could use a set screw (they are available 3/8 diam
at 3'' long) and use two jam nuts at the proper spot and a 3/8 acorn nut.
Alternately you could drill a hole in the nut and put a set screw and fix it
at the proper location.

Now here's an even simpler way--

Use a hanger bolt.  That's a bolt that has lag threads on one end and
machine threads on the other.  Put a jam nut at the proper position and fix
it with a set screw and or locktite, cut off the excess and with a hack saw
cut a slot for a common flat blade screw driver so you can adjust it from
the top.

You may have to counterbore the rim for clearance of the nuts or chisel some
of the soundboard to give space for lowering the plate.

Some of my RPT rebuilder friends say they have to take the plate in and out
a dozen or so times to get it right.  No way! Jose!
More than once is too much.

Happy down bearings.  Questions?

Carl Meyer




-- Original Message -----
From: <Yardarm103669107@AOL.COM>
To: <pianote

ch@ptg.org>
Sent: Sunday, February 04, 2001 5:53 PM
Subject: Re: Positioning Plate/Action


> In reference to the screws Horace was referring to:
> They are called cap screws, and if you get 1/2" OD thread 7/8" face with a
> 5/16" hex, then prepare the plate lag hole by drilling out about 1/2" down
> with a 7/16" bit, then thread the cap screws down and place the plate on
> them, you can go through the plate lag holes with a hex wrench and adjust
> height. Ideally, the cap screws should be milled so that the top face is
only
> 40-50 thousandths so that it will flush out on the soundboard. New, the
cap
> screw head has a bevel which will open out the hole in the soundboard if
not
> milled down. This is particularly true on Steinway with thick plate bosses
> which sit down practically on and sometimes in the soundboard. This idea,
by
> the way, which I've been using for years for plate bearing setting along
with
> bridge kerfing techniques, was originally from Nick Gravagne; see also his
> class at the Reno meeting on grinding plate bosses.
>
> Paul Revenko-Jones