Hammer height conundrum on a '46 Hardman grand

[George Whitty]

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