Steinway "pinning" dilemma

[fssturm@unm.edu]

Quoting Jim Busby <jim_busby@byu.edu>:

> Thanks Fred,
> 
> I've been out of state for a week.
> 
> Several excellent techs have told me that Steinway does it the way
> they
> do to "cover a flaw in the design", i.e. in order to get more power
> they
> hang a heavy hammer, and in order to compensate for the heavy
> hammers
> they have to reduce friction to make proper touchweight specs. 
> 
> After spending the day with Eric I'm not totally a proponent of
> their
> way, but I'm definitely more open to it. I agree that if that's how
> they
> do it I should at least look into it...
> 
> BTW, maybe my readings were not as accurate because of how fast I
> ran
> through everything. Just trying to get a feel for things there. But
> if I
> increased 5+ grams in the hammer flange doesn't that multiply for
> DW?
> 
> Jim 
> 
Hi Jim,
   Thanks for your report on Eric's comments. Very interesting and useful.
    I don't think the low friction has anything to do with heavier hammers. To the 
best of my knowledge, the increase in hammer weight was addressed with 
design changes - particularly change in knuckle placement with resultant 
increase in dip, but I believe there were a few other, more subtle changes as 
well. I've had more of a tendency to suspect that the statement "as long as the 
center is firm, it doesn't matter how much friction there is" had more to do with 
setting limits on warrantee liability. To put it crassly, "If you want more friction (for 
whatever reason), that's fine, but Steinway isn't going to pay." 2 grams has 
always been my absolute bottom limit, and 1 seems awfully low. But I'm willing 
to suspend disbelief to a certain extent.
   The friction in a hammer flange doesn't transfer directly (numerically) to 
downweight at all, and certainly doesn't multiply. Hammerflange friction is 
usually a fairly small portion of overall friction, which is a small portion of down 
weight. The largest portion of action friction is knuckle to rep lever/jack, then 
wippen cushion to capstan and keybushing to keypin. Action center friction is 
generally the smallest portion. Unless action centers are nearly frozen, their 
contribution to measured DW (or friction calculated from DW and UW) is well 
within 5 grams. As Don Mannino noted in an earlier post, he finds increasing 
hammershank center friction from zero to (I think it was) 4 grams increases DW 
by only 1.5 grams, which sounds about right.
Regards,
Fred Sturm
University of New Mexico