measuring ratios/ popsicle puzzle

[RicB]

Hi Ed

Seems to me that you are saying here that your choice of SW's and FW's 
is made without (or little) regard to what your existing action ratio 
is.  Is that what you are saying ?

Otherwise... lets see, you say you have around 47.6 mm blow, 10~ mm 
keydip and I assuming lettoff is somewhere around 1.5 to 2 mm, and still 
have 12.7 mm down to the cushion, (thats a whopping 60.3 mm from string 
to cushion... cant remember when I've ever run into that.)  You cite a 
0.3 inch (7.6 mm aftertouch) which must be a typo for sure... perhaps 
you meant 0.03 inches (0.76 mm) ?  If this be the case I see no reason 
to change your (distance) ratio really.

Your DW / UW  BW figures are not what I would call ridiculously low.  A 
BW of 36-38 is very common on Steinways.  I typically shoot for 52 grams 
DW in the lowest bass, graduating to 48 grams in the high treble and 
want between 25 and 30 grams of UW throughout.  Even Yamaha CF III comes 
in at 42 grams BW and thats heavy in my book. But reducing FW's to raise 
the BW is what I would do as well if I wanted to make the thing heavier.

As for what I would do to deal with your cushion problem. (Which seems 
to be your only problem) Since you have very good regulating distances 
othewise, and assuming you are getting adequate and not excessive jack 
clearance...  I'd beef up your exisiting cushions as much as I could get 
away with first. Since you dont cite anywhere what your bore distance is 
I dont know for sure what you can do with that... but if you can 
increase it a bit and still keep a reasonable rake you can win a tad 
there.  Still... you need to get from 12.7 mm down to around 4 if you 
can.  You might get 5 ---  tops 6 mm with the formentioned two bits. 
That leaves at least 3-4 mm left and thats pushing it.  Raising the 
stack (perhaps just the back ?) was mentioned. If you are getting past 
the whippen /balance rail line of centers at half blow, then by all 
means raise the stack.  If you are not reaching it at all then I 
wouldnt. Whats left as far as I can see is to raise the ratio a tad... 
forcing an even longer blow distance. Since this (raising the ratio) 
will also increase your BW... this might be what you are thinking. A 
capstan move .

Cheers
RicB


      As far as confusing the method of determining ratio between this and
    Stanwood's, I don't use David's procedures for arriving at my
    relationship between
    SW and FW.  I use a visually determined curve drawn atop the
    charting of my
    FW's.  Where that curve orginates is in my choice of SW, which
    depends on the
    size of the piano, the intended venue, and the subjective desires of
    the
    pianist.  There are limits to how high FW can go without bringing in
    unavoidable and
    undesirable inertial results which, in some configurations, may
    force the SW
    lower than optimum.  How much keydip can be used will limit the
    amount of
    ratio available, given a set hammer blow.  I strongly prefer to
    limit key dip to
    .400" and I like no more than . 30" aftertouch.   

         Case in point. (here is the puzzle part)
          I am currently preparing to rehammer and reshank a 10 year old
    D which
    has a very high string height and a very low ratio (4.9). At 1 7/8
    blow, the
    shanks are almost 1/2" off the cushions.   This action currently has
    17 mm
    knuckle distance, SW in the upper middle range, FW in the average
    range, and
    ridiculously low DW of 50 gr. in the bass, 44 gr in the area of note
    25, and 40-42
    gr. from note 32 on up.  BW on A0 is 40, tapering down to 33 at note
    73.  
          I could elect to reduce the FW, keeping all other things near
    the same.
    However, this would not address how high the hammers are off the rest
    cushions.  It would not increase the power,either.  What would you do?
    ( I already have a plan of action, which entails three changes, but
    will be
    interested in other's interpretation.)  

    Regards,
     
    Ed Foote RPT
    http://www.uk-piano.org/edfoote/index.html
    www.uk-piano.org/edfoote/well_tempered_piano.html