[pianotech] Interesting upright jack

[David Ilvedson]

I think you're right that it helps return the jack...I've got an old Mason/Hamlin with the same thing and that's what I thought it was...I mean what else?

David Ilvedson, RPT
Pacifica, CA  94044

----- Original message ----------------------------------------
From: "Scott Helms, RPT" <tuner at helmsmusic.net>
To: pianotech at ptg.org
Received: 10/7/2009 6:00:08 PM
Subject: [pianotech] Interesting upright jack


>Hi list -

>I tuned a 1907 Mason & Hamlin upright recently, and I noticed interesting
>components on the jacks and catchers that I hadn't seen before (see
>attached photo). There is a brass piece on the backside of each jack which
>looks like it might serve as a spring to help the jack return under the
>butt. The pic is pretty fuzzy (taken with my cell phone), but I think you
>can see that the brass piece is flush against the backside of the jack,
>and it's flat except for a small "crook" near the top. This shape is what
>makes me think it's a spring. There is also an extra piece on the backside
>of the catcher which aligns with the crook in the brass piece, although
>(at least in its current poorly regulated state) the jack doesn't go back
>far enough for the brass piece to actually contact the back of the
>catcher. The piece on the backside of the catcher has a thick, dense felt
>similar to backcheck felt.

>The jacks also have the standard coil spring under the tender. I know M&H
>was pretty inventive and often experimental with many components of their
>pianos in the early 20th Century, so I'm not surprised to see something
>new, but I'm curious. Has anyone seen these before? Am I right in guessing
>that these are an assist spring for speedy jack return? If so, when I
>regulate this piano, should the blow distance be set such that, with
>proper dip and aftertouch these brass pieces DO contact the backside of
>the catcher?

>Scott
>------
>Scott A. Helms, Registered Piano Technician
>480-818-3871
>www.helmsmusic.net