Hammer height conundrum on a '46 Hardman grand

[Michael Spalding]

George,

Before changing any design dimensions by shimming up the stack, I would
recommend that you go through all the regulatioin steps on a handful of
sample notes to see if there are any other quesstionable points.  For
example, someone mentioned earlier that flattened knuckles will contribute
to hammers being too low at rest.  Flattened knuckles will also cause the
let-off distance to increase, and drop to increase.  Sometimes, especially
in combination with heavily filed hammers, to the extreme that there is not
enough range of adjustment to get let-off and drop into spec without
bolstering or replacing the knuckles.  My point is, before you consider
design changes, make sure you have a handle on ALL of the regulation
problems.  Unless you rebuild with new parts, and custom bore to suit your
actual string height, your regulation will have to be a compromise.  Shank
ht. above the cushions would get a lower priority than many other
parameters.

FWIW, I rebuilt a 1928 Hardman in 2003, and the bore distance in the
tenor/treble was 2 to 2 1/16 inches.

Others have recommended you obtain Reblitz, but didn't you start your first
post by telling us you were using his book already?

regards

Mike


> [Original Message]
> From: George Whitty <gwhitty@optonline.net>
> To: Pianotech <pianotech@ptg.org>
> Date: 1/11/2005 11:34:34 PM
> Subject: Re: Hammer height conundrum on a '46 Hardman grand
>
> After a long, careful examination of my piano (and my assumptions about 
> my piano), I've come to the conclusion that my hammers have been filed 
> several times.  They're actually faceted, some in a fairly lumpy, 
> asymmetrical way, and looking really closely I can see and feel two 
> distinct rounds of filing, with possibly more;  This is probably where 
> I'm losing most of that 3/16".   I'm not in any position to replace the 
> hammers in this piano for now;  that one's WELL beyond my scope, so I'm 
> looking for the best compromise.  It occurs to me that by shimming with 
> a couple 1/16" washers beneath each of the 8 support posts on the upper 
> structure of the action (thus raising the hammers 1/8") , then turning 
> up the capstans and adjusting the backchecks (these were going to need 
> a regulation anyway), I could at least preserve more of the correct 
> geometry between the wippens and the hammers than I would by simply 
> screwing up the capstans until the hammer travel is 1 3/4" but the 
> hammer shanks are sitting way above the hammer rests.  The disadvantage 
> of this approach is that I have to crank the capstans even higher (or, 
> as Barbara suggested, fill out the wippen cushions more) to raise the 
> hammers than I would if I left the upper action where it is, thus 
> taking advantage of the leverage (in which lifting the wippen a little 
> raises the hammer a lot).  Has anyone done anything like this?  Is it 
> just a terrible idea, or a workable kluge until I can pay someone to 
> replace all the hammers one day?
>
> Thanks again,
> George
>
>
> > 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
>
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