let-off

[Tom Cole]

Tom,

What Newton said about the different effects of the compression of
regulating punching vs. hammer knuckle (or butt leather) due to their
respective leverages is a major factor here. Just a little bit of a
flattening of the roller (or butt cushion) can widen the letoff
significantly compared with the compression of the letoff punching.

Another thing that frequently happens in neglected instruments is that
the balance rail felt becomes compressed which reduces the key stroke,
eventually causing the hammers to bobble. What technicians sometimes do
to cure the bobble is to make the escapement earlier, rather than to
reduce the hammer stroke (better) or restore the keydip (best).

Possibly this is what Joe Goss was getting at by his mention of the
"balance rail felt, hammer rest rail and the felt that holds the rail in
place" but I thought I would clarify.

With apologies for all this talk about "let off" in a public forum,

Tom Cole



Thos. D. Carpenter wrote:
> 
> Dear illutrious list,
>     If, as the let-off button felt compacts...the let-off moves closer
> to the string, do we continuously find, on instruments where let-off
> regulation has been neglected, that the let-off has moved further from
> the string?
> Tom Carpenter, associate

-- 
Thomas A. Cole, RPT
Santa Cruz, CA
mailto:tcole@cruzio.com