Richard: You need to look at the force leverage first. What is the key ratio and the knuckle radius. Those two will tell you a lot. Assuming normal gluing distance (130 mm), a knuckle radius of 17mm, and whippen leverage that is normal, the key ratio needs to be not greater than .55 to accommodate a medium hammer weight without excessive lead. Less is better but it seems that below .53 you can begin to run into problems with dip or blow. I would try to resolve friction issues before you go any further. David Love ----- Original Message ----- From: "Richard Brekne" <rbrekne@broadpark.no> To: <pianotech@ptg.org> Sent: September 06, 2001 9:35 AM Subject: Re: Seiler Job > Thanks Bill and Jim, I understand and was (am) tempted to install assists for > the rest of the action and go that way instead. One big thing makes me back off > at first glance... and that is the fellow who uses this grand likes it heavy to > the touch. I figure probably going with a BW spec of 40. At least I doubt I > should get under 52 grams down weight with this fellow. I interpret that out of > his declaration that he want to leave the weight as it is, and a look at the > data shows both heavy touch and a deal of friction (sluggishness to be read in > here ??) > > Anyways with that heavy a touchweight, and hammers starting off at around 12 > grams and curving down to about 5.8 grams I wont really need all that much lead > to begin with ??. Whadya think ?. I am guessing without really looking closely > at my sample data yet so maybe I am off the go in the wrong direction. > > Bill Shull wrote : > > Being so close to being able to do a support spring retrofit, I would be > inclined to put springs in the rest of the whips, giving me the opportunity > to get rid of excess key lead mass, be able to put the mass where I want it > (the hammer), and get more control of balance weight (this before studying > your spreadsheet...). I am guessing the whips are ready, just need the > springs and flanges/cord, which Renner might be talked out of, especially if > you need several sets. > > Bill Shull > > > JIMRPT@AOL.COM wrote: > > > Richard; > > The operative word here should be "whippen *assist* springs". It is when > > these thingees are used for 'crutches' that problems stick out such as your > > "abrut" (sic: abrupt) shift in weights. Just go ahead and address all the > > friction issues first before you make any decision on disconnecting these > > puppies. Adjusted correctly they can be of significant benefit in an > > intrinsically heavy bass section. > > My view. > > Jim Bryant (FL) > > -- > Richard Brekne > RPT, N.P.T.F. > Bergen, Norway > mailto:rbrekne@broadpark.no > >
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