Spurlock Damper Design (larger dampers in bass for old upright)

[Ed Sutton]

Terry-

No, step one is: Make a sample damper and see if it works.  This is how you
find the answers to the other questions.  Step two will probably be: Make
another sample damper, etc.

The dimensions Bill gives in the article are a good place to start.
1/8 inch boards seem a little thick. Seems to me I found something a little
thinner.  Someone mentioned (model) aircraft plywood- that would be very
good, and can be found in 1/16 inch thickness.

I used Schaff #947 Grand damper lifter felt.  It's 2mm thick. I liked it
better when it was blue, but now they are selling brown. O well.
Temperament strips would be too thick and soft, I think.

When you do it, you will see the problem of clearing the damper wires when
the damper lifts off the string. If the piano originally had very small
dampers, the lower end of the long damper will tend to bump into neighboring
damper wires.  On pianos designed with long dampers, the wire is bent in a
dogleg to clear the neighboring dampers.

Keeping the damper as thin as possible front to back will help, so will
getting it as close to the hammer as possible.  Finally you may find that a
slight change of dimension, and possibly trimming the ends at angles will
get larger dampers on the piano without having to rebend or replace the
damper wires.

But all of this is easier to see in the piano than to describe in words.
Therefore, make that sample damper, try it, refine it, etc.

Is the piano in your shop? It's a lot easier to solve the little problems
with the piano there.

Have fun! It's a satisfying job to do. You'll feel high class about it!

Ed S.

----------
>From: owner-pianotech-digest@ptg.org (pianotech-digest)
>To: pianotech-digest@ptg.org
>Subject: pianotech-digest V2001 #1115
>Date: Fri, Aug 31, 2001, 7:00 AM
>

> -----------------------------
>
> Date: Fri, 31 Aug 2001 07:45:03 -0400
> From: "Farrell" <mfarrel2@tampabay.rr.com>
> Subject: Re: Spurlock Damper Design
>
> I have been contemplating the sequence of procedures I would use to
> construct a set of dampers and the best I can come up with is as follows:
>
> 1)  Cut appropriate number of 1/8" thick X 3/8" X 2-1/4" (or whatever length
> you decide) damper boards.
>
> 2)  Cut 3/8" wide felt damper wedges, etc. into 5/8" lengths (or whatever
> length you decide).
>
> 3)  Glue felt to board, being real careful with felt piece alignment
> (perhaps best to use a jig for training).
>
> 4)  Line up dampers side-to-side, felt side down, and glue 1/8" thick spring
> rail felt to back of dampers boards.
>
> Is spring rail felt the best to use (that is what Bill Spurlock uses)? What
> about muting strips - they are available in various thicknesses - perhaps an
> advantage to get best fit? What about understring felt - or is that too
> firm? What about action cloth - again, available in various thicknesses? Or
> any other felt work best? Any thoughts? Thanks.
>
> Terry Farrell