When to do it

[thepianoarts]

on 12/24/00 7:09 AM, Clyde Hollinger at cedel@supernet.com wrote:

> Friends,
> 
> What happens to lost motion, particularly in spinets and consoles, when
> the humidity changes?

Clyde,

I don't think changes in humidity effect lost motion.

> When does it increase or decrease, and why?

    Lost motion takes a long time to change, with one exception: new pianos.
In a new vertical, lost moition usually decreases rather quickly in the
first year or two. The hammer rest rail felt, and the hammer rail support
bracket felt compress rapidly. This allows the hammer/shank/butt assembly to
fall back, causing the butt slide to get closer to the jack top.
    The balance rail and back rail felt also compress. This by itself would
cause an increase in lost motion. It is not unusual for an old upright to
have  2" blow distance, and let-off happening at 1/2 ".
> I should know by now, but I don't, and I did run into trouble once by
> doing it at the wrong time.

    I don't think timing caused the trouble. I am going to guess what
happened is that you experienced an after-touch change when you revisited
the piano. (Lost motion would only show a dramatic change if new felt was
installed at the balance rail, hammer rest rail etc., or if the key bed and
underlying structure is not stable.)

 If you reset let-off timing, along with making a correction in lost motion
and blow distance, and the piano in question was an older one, the let-off
regulating button felt could be deeply 'dented'.  When this button (let-off)
is moved to a new position, there is now a good chance the jack heel is now
touching 'fresh-never-been-touched' felt. The jack heel will quickly
compress this felt. Compression in the let-off button causes two changes in
a finely regulated piano.
 

#1- Most importantly, let-off timing is changed. The hammer will travel
closer to the wire before triping. It could even block, (was that the
trouble?) if you had set let-off timing close, last time arround.

#2- After-touch decreases. When the let-off button felt compresses, the
result is the same as moving the button away from the jack heel. The jack
ends up 'tripping' less. This could cause the hammer to 'bobble'. More
trouble.

Are any of these suggestions relevant?

Dan Reed

Dallas Chapter