[pianotech] Interesting upright jack

[AAA Piano Works, LLC]

Hi Scott, Nice to hear from you again.

I have not seen this before, but I am sure someone has.

Brian

p.s.  I am loving the "no teaching" life!!

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Scott Helms, RPT
Sent: Wednesday, October 07, 2009 9:00 PM
To: pianotech at ptg.org
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
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Scott A. Helms, Registered Piano Technician
480-818-3871
www.helmsmusic.net