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

[Israel Stein]

At 11:00 AM 12/18/2006, David Skolnik wrote:
>>I.S.: Replacing the {current style Steinway] backchecks with the 
>>Tokiwa- made old-style Steinway backchecks (longer) cleared up all 
>>the problems on both pianos ($150/set, Pianotek). It seems that on 
>>a lot of them the hammer tails are just too short for the new 
>>style, shorter backchecks...
>>
>>Israel Stein
>
>D.S.: Israel - As with Wim - you also did not indicate the 
>manufacturing year of your pianos.  It's true that there was a 
>period when the tails were extremely short, but that's not too 
>recent, in my experience.  If it were only the height of the checks 
>in relation to the tails, why couldn't you simply raise the 
>backchecks?  As an experiment, it falls short of completely 
>explaining the issue, since there are undoubtedly differences in a 
>number of characteristics between the two brands.  Can you look at 
>the two side by side and compare them?
>
>David Skolnik

Finally got a chance to closely examine the two backchecks side by 
side, and to my great surprise found out that the height difference 
between the two is negligible - 1/2 of a millimeter. The replacement 
backcheck appears to be longer at first glance because it's body is 
1/2" longer than the current Steinway backcheck - but the wire is 
shorter, so the height difference turns out to be negligible (at 
least as installed in this particular 1999 Steinway D). So, David, 
you are right - there is something else happening here, because the 
difference in function was quite striking. The regulation fell into 
place very easily. I simply duplicated the angle from the old 
backchecks - and all the backchecks were working fine after one 
regulation pass. The client noticed the difference right away.

So, what could it be if not the height?

Here are the dimensions (excluding wire):

Current style Steinway: 30 mm tall, 9 mm wide, 12 mm thick at base - 
tapering to 9 mm at top of moulding
Old-Style Steinway made by Tokiwa: 42 mm tall, 10.5 mm wide, 12 mm 
thick (not tapered). I compared it to an old Steinway backcheck on 
one of the pianos at SFSU - and it is pretty much identical (at least 
dimensionally).

So, does the greater mass relative to the hammer have an effect? Is 
the front-to-back tapering on the new style a problem?

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







-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://www.moypiano.com/ptg/caut.php/attachments/20061222/b3200aeb/attachment-0001.html