[CAUT] Backcheck replacement revisited (was: balancier/wippens report)

[RicB]

Hi Israel

I've always operated on the theory that the tail wants to be able to 
slip into the check as easily and with as little friction as possible so 
as to create more pressure outwards on the check... ie tensioning the 
check and wire away from the tail.  That it was THIS tension that held 
the hammer in place.  IME rough tails are associated with more checking 
problems to begin with and accomplish far more wear on the leather of 
the check over time.  I think a firm check with a sufficiently flexible 
wire fits well with this idea.

There seems to be a point where smoothness of the tail and leather can 
be too much of a good thing as well. When I run into tails that have a 
kind of glaze on them they dont seem to hold well at all. I routinely 
sand this off with 180 grit paper in the vertical direction. 

Cheers
RicB


    There is almost double the thickness of felt on the old-style
    backcheck (5.5 mm as opposed to 3 mm) and the buckskin is thicker and
    firmer. There is much less "give" in the felt of the old-style
    Tokiwa-made backcheck than in the current Steinway backcheck. Is that
    a factor? (I would think that after 6 years' use the felt would get
    compress and become firmer - not looser - so age does not appear to
    be the problem here...)

    Also, when I was regulating these replacement backchecks, the wires
    on them felt "springier" than the originals.

    That's all the differences I can think of. It just seems to me that
    these older-style backchecks are more forgiving - and will function
    and regulate well over a broader range of tail shapes and backcheck
    angles than the current style. Just an initial impression... There
    are two high-quality rebuilders here in the San Francisco Bay area
    who replace any current-style backchecks in their projects with these
    old-style Tokiwa ones as a matter of course. The only downside I know
    of (aside from the cost and the labor) is that sometimes if you don't
    want the checking too close, you'll have trouble clearing the
    sostenuto and it may be necessary to cove the mouldings...

    So, any speculation as to what makes these backcheks work so much
    better? Because they do.

    Israel Stein