[CAUT] Checking

[Fred Sturm]

Hi Jon,
    I generally agree, on new work. Facing a piano with existing parts, in
unknown condition, is the scenario I was writing about. Yes, the 2mm or so
works well (assuming a standard drop equal to letoff, and measured just as
it drops, not with some undetermined, usually too large aftertouch as I seem
to find all too often). If you aren¹t careful to set up your keyframe to
match key dip in the piano, this can be anyone¹s guess as a measurement.
    Faced with a tail profile that is unknown, one can remove a hammer and
do an approximate compass thing using a bit of thread, holding one end about
2.5 to 3 inches along the shank, and with a loop on the other end scribe
with a pencil point. But usually I just observe it passing the check on the
upstroke to see whether it has a bump and how bad.
    And, of course, tail length is what it is. It¹s nice to control what you
put on, but you also have to try to make the existing part work far too
often <G>.
Regards,
Fred Sturm
University of New Mexico


On 12/27/06 4:48 PM, "Jon Page" <jonpage at comcast.net> wrote:
>> >there are a few good principles: smoothly curved profile of the tail, no
>> >?bump?; there is a limit to how high the check can be relative to the shank
>> >at rest, and this varies a bit with tail length; angle of check needs to be
>> >within fairly tight parameters,
> 
> I generally use a 3" arc on the tails. Due to the degree of coving, anything
> shorter leaves too thin of a tail section. I order hammers un-coved and find
> the
> coving process unnecessary. It removes such a minute amount of weight which
> has a
> negligible effect on touch weight (certainly not worth the effort). I also
> ease the 'square'
> end with a rough file and fine-file the tapered edges to remove 'hairs'.
> 
> Tail length 1 1/16", shorter lengths brings the check closer and the tops of
> the back
> checks can hit the shoulders of the hammers.  I order hammers with a molding
> 1/8" longer than my longest bore. I then sand all tails to even length after
> hanging.  Why have varying tail lengths as a
> result of a tapered bore?
> 
> Back check height, I have not gone wrong with setting the height to even-with
> or 2 mm
> below the tail at drop position.
> 
> Angle, 72 degrees from key stick. That's the leather face, not the wood rear
> profile.
> 
> That's my recipe for success.


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