Backcheck height

[David Love]

Why do you have to replace the backchecks in order to lower them?  Just tap
them down.  The backcheck being to  high won't in and of itself create
problems with low checking.  But the fact that you must move the backcheck
away from the hammer to keep it from dragging on the tail on the way up or
to keep it from hitting the low shoulder will.  Suggestions by Ed Foote
were right on the money.  The radius of the tail must be 1/2 the hanging
distance (1/2 x 5 1/8" = 2 9/16"), the low shoulder on the bulkier hammers
may need to be trimmed away if they are too low, and the backcheck height
will have to be set along with the angle of the check.  The angle should be
such that you can push the hammer into the check, but  you should get
increasing resistance as you go down.  If the angle is too acute and you
cannot push down at all, you will get what's known as "hard checking" and
you will feel it through the key.  If the angle is not acute enough, the
hammer will push through the check and with hard blows you will get
checking that is too deep.  The other problem that occurs on Steinway
hammers is that the tails can be too short.  Check the length from center
of the bore.  It should be 1".  Often it is not in the tenor section.  That
will also make high checking a problem.

David Love
davidlovepianos@earthlink.net


> [Original Message]
> From: Avery Todd <avery@ev1.net>
> To: Pianotech <pianotech@ptg.org>; <davidlovepianos@earthlink.net>
> Date: 5/27/2003 4:56:10 PM
> Subject: RE: Backcheck height
>
> Thanks David,
>
> I've been delaying posting about this but I think now, I need to.
>
> There is also another potential problem which I've had to deal with on our
> newest D. I don't know if it was done that way at the factory or at the
> dealer but the backcheck height is appreciably too high. I've had
"clunking"
> noises from the hammer shoulder rebounding on it; notes failing to repeat
in
> a very fast repetitive "situation" (had complaints about it), because the
> shoulder was getting hung up on the backcheck (I couldn't make the hammer
> check high enough because the checks were too high), plus what has 
already
> been mentioned about the tails rubbing on the backchecks. It's been a
royal
> pain, believe me.
>
> As soon as I can get the money (considering Texas' budget problems), I'm
going
> to replace the backchecks and wires and set them so that the tail at
letoff is
> app. 2 mm. above the backcheck, assuming the hammer bore distance is
correct,
> of course. :-) That's what I've always been told anyway and it has always
> worked for me! No matter what the dealer tech likes! :-)
>
> Avery
>
> At 02:08 PM 05/27/03 -0700, you wrote:
> >Umm, because it works.   Lower and you will not get the hammer to check
> >high enough with adequate surface contact between tail and check, higher
> >and the tail will tend to catch on the hammer or the check will catch on
> >the lower shoulder of the bass hammer.
> >
> >David Love
> >davidlovepianos@earthlink.net
> >
> >
> > > [Original Message]
> > > From: Alan Forsyth <alanforsyth@fortune4.fsnet.co.uk>
> > > To: Pianotech <pianotech@ptg.org>
> > > Date: 5/27/2003 1:00:46 PM
> > > Subject: Backcheck height
> > >
> > > Dear listed ones,
> > >
> > > >>>>"The backcheck should be set so that when the hammer rises to its
> > > highest point (at let-off) the bottom of the tail is 1/16" above the
top
> >of
> > > the backcheck.  Tails should be 1" long ......
> > >
> > > David Love">>>>
> > >
> > > Umm ....Why??
> > >
> > > AF