Aftertouch Question

[Roger Jolly]

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Hi Terry,
             For a performance regulation,  Top key quality key bedding is a
given not a  choice.
Japanese and Korean action rails will not stay stable at the 1/32"(let off)
tolerance and handle the humidity swings, you can get it up this tight for a
performance but don't expect it to last. 
Remember that Fir or Spruce expands and contracts quite a bit tangentially, so
the rails will move quite a bit more than their maple counter parts.

Now I become bilingual, dip on most Asian pianos should be in the 10mm ball
park. Shot for about .020" after touch.

To attain 1/32" let off and minimal drop, with 1/4" ppp checking in the lower
registers the tail geometry has to be very good, and back check faces,
parallel
with the hammer rail.

1. Tail should be at 90 degrees to the hammer shank, if not, and is angled,
the
check has the tendency to push the hammer tail out of check.  If check and
tail
is at 90 degrees to the hammer rail,  the check is evenly trapping the hammer
and shank against the centre pin.

2.  Tail radius needs to be half the distance of the centre to tail radius, (
about 5") 
So arc the tails at 2 1/2". Bill Spurlock's jig will do a good job. Use new a
80 grit belt.
Checkering should not be needed, nor is it desirable.  Gina and I differ on
this a little, If you have a heavy set of hammers, I will 45 degree lightly
checker the bass only with a coarse file, NOT a checkering file. But we both
agree that for a normal regulation checkering is not needed.

Terry, if bedding, tailing geometry, back check height, and rake are not in
order, you are not going to achieve the tight specs that you are after.

Hammer flange centre pinning starts to become critical at these tolerences, so
be on your guard in this area.

PS. Gina and I have just finished writing, about a 5 page side bar to our
interactive reg articals just on checking and spring tension pitfalls. I think
it's chapter 7?

Well I guess we are both long winded.  <g>

Hope this helps





A

t 06:20 AM 26/05/00 -0400, you wrote:
>Thanks for your thoughts Roger. The action frame is soft & hard wood
>composite - mostly soft with beech strips where the rail pins go. You may
>have a good point that the frame flexes in a different way on the bench than
>in the piano and that is changing checking. I fine tune let-off in the
>piano.
>
>"> When you say it check's out of the piano, I'm assuming you are using a
>> regulation rack, if not, the hammer is travelling higher than the string
>line."
>
>Yes, absolutely. That was a critical part of my question. With let-off real
>close and drop real small, aftertouch would have to be in the less than
>ten-thousandths of an inch range (I'm pretty quick w/ metric conversions -
>but I hope you are comfy w/ english units here!) to keep the hammer from
>blocking against the string upon completing the keystroke through
>aftertouch. Yes? When setting letoff & drop real tight, how do you handle
>aftertouch, i.e. how do you make it pleasing to the touch, yet keep the
>hammers from blocking against the strings?
>
>Thanks billions for any thoughts
>
>Terry Farrell
>Piano Tuning & Service
>Tampa, Florida
>mfarrel2@tampabay.rr.com
>
>----- Original Message -----
>From: "Roger Jolly" <baldyam@sk.sympatico.ca>
>To: <pianotech@ptg.org>
>Sent: Friday, May 26, 2000 12:37 AM
>Subject: Re: Aftertouch Question
>
>
>> Hi Terry,
>>              If the action frame is the soft wood type( not  familiar with
>> Boston's), there is Lot of flexibility in the frame. Bench reg to piano
>> rarely works.  The key bedding is critical when you are working at those
>> tolerences, so the regulation has to be done in the piano.
>> When you say it check's out of the piano, I'm assuming you are using a
>> regulation rack, if not, the hammer is travelling higher than the string
>line.
>> Regards Roger
>>
>>
>> At 10:02 PM 25/05/00 -0400, you wrote:
>> >OK grand regulation techies, here you go! Two related questions about
>> >checking and aftertouch.
>> >
>> >I just did a full regulation on my Boston GP178 (5' 10" grand). I set
>blow
>> >dist. @ 1-3/4", let-off as close as possible (about 1/32"), and drop (as
>> >recommended by Steinway) as short as possible - about 1/16" or maybe a
>tad
>> >more - but less than 1/8". I have my checking up nice and high - about
>3/8"
>> >over the treble & up, about 7/16" in tenor, and about 1/2" in bass. Key
>dip
>> >is about 0.45".
>> >
>> >Out of the piano, all hammers check on even the softest blow (I
>roughed-up
>> >the tails a tad). When I put the piano in the instrument, I often get a
>few
>> >hammers that will not check on a light blow. And of course, because I
>have
>> >the let-off so close and drop so little, the hammer rises up and
>> >blocks/bobbles on the string when pressing the key through aftertouch.
>> >
>> >Question #1: Should ALL hammers ALWAYS go into check, even on a very,
>very
>> >LIGHT BLOW?
>> >
>> >If answer to Question #1 is yes, then Question #2 is: Why do all hammers
>> >check out of the piano but not when action is in piano (keep in mind, I
>am
>> >talking about very soft blows).
>> >
>> >If answer to Question #1 is no, then Question #2 is: If it is normal for
>> >hammers to occassionally not check on a very soft blow, when let-off and
>> >drop are real small, is it really feasable to make aftertouch the
>necessary
>> >10 thousandths of an inch (or there abouts - perhaps even less). Because
>if
>> >aftertouch is any greater, the hammer will simply rise up into the string
>> >and mute it in a very nasty manner. I like alot of aftertouch - generally
>in
>> >the ballpark of 50 thousandths or so. I can't do that unless I am sure
>that
>> >all hammers will check every time a key is struck - even when struck VERY
>> >LIGHTLY.
>> >
>> >Any good input for me?
>> >
>> >Terry Farrell
>> >Piano Tuning & Service
>> >Tampa, Florida
>> >mfarrel2@tampabay.rr.com
>> >
>> Roger Jolly
>> Saskatoon, Canada.
>> 306-665-0213
>> Fax 652-0505
>>
> 
Roger Jolly
Saskatoon, Canada.
306-665-0213
Fax 652-0505 
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