Hammer height conundrum on a '46 Hardman grand

[George Whitty]

Hi, Mike:

   Thanks for the reply;  I raised the capstan on my middle C to get the
hammer 1 3/4" from the bottom of the string and took some measurements
(didn't have time to do more keys today).  Here's what I end up with:  from
the cushion to the shank is 5/16", the hammer bore is 1 31/32", and the
distance from the hammer to the bottom of the strings is now 1 3/4".  I took
a look at a couple pianos today, a Steinway and a Yamaha, and their hammer
shanks sit a very neat 1/8" above their cushions the entire length of the
keyboard.  Thus, doing the math, it seems that to achieve that in my piano,
middle C's cushion should sit 1 31/32 + 1 3/4 + 1/8 + half the diameter of
the hammer shank below the strings;  unfortunately that 1/8" in my piano is
a pretty consistent 5/16" or so, which makes me wonder if the whole keybed
is somehow sitting 3/16" too low in my instrument.  For those still bearing
with me, I have a couple questions based on this information:

1.  I notice that, while there's a good deal of resistance trying to push
the hammer down to the cushion with the jack still under the knuckle, it'll
go right down easily with the jack tripped.  Is the cushion there only to
catch the key if it rebounds too fast for the jack to get back under the
knuckle, in which case I think my keys work fine even with the 5/16" gap?

2.  Could someone enlighten me a bit more as to how to determine whether my
hammers have been filed?  Feeling around the edges of some of them, I now
notice a little very slight ridge, a little angle as though some felt had
been removed (the little ridge sits at about 9:30 and 2:30 on the hammer)
they're definitely not just one totally smooth arc.  I'm just not sure
whether this is something done at the factory as a way of voicing the things
or something.  In any case, I think they'd look more out of round if there
was 3/16" missing off the tops.

3.  Is 1 31/32" a typical measurement for a middle C hammer bore, or does a
"typical measurement" even exist?  Is there somewhere that I might find out
what this measurement SHOULD be for my piano?

Thanks again to everyone helping me out with this intriguing problem..

George Whitty


> Hi George,
> 
> As Ric B. mentioned, something does not add up, literally, if the shanks
> are 1/2" off the cushion when the blow distance is 1 3/4".  The couple of
> Hardmans that I've seen / worked on have regulated to fairly conventional
> dimensions.  Picture the virtical distance from the rest cushion on the
> wippen up to the strings.  It wil be subdivided into 1) clearance to shank
> at rest, 2) hammer bore length (plus 1/2 shank diameter), and 3) hammer
> blow distance.  If 1) and/or  3) are larger than they should be, then 2) is
> smaller than it should be, either by design or through wear.  Let us know
> what the bore distance is, for several hammers from bass to high treble.
> Also, take a look at the string grooves - how deep and long are they, and
> are they perpendicular to the molding ?
> 
> Mike