Personally, I don't like going to 18 mm for the knuckle. If you do, consider repinning the balancier flange so you can put more tension on the rep spring. Otherwise, you will have to regulate it too close to the edge and the jack return can suffer. If the picture below indicates the strike weight of note 20 at 11.9 grams, I'd use a lighter hammer. I don't see why you need a 10 gram hammer at note 20. Nine grams should be plenty for your 6'4" Knabe with new and sensitive soundboard and you could probably go even lighter. Moving the knuckle (better to have bought the shank with the correct knuckle to begin with) to 17 mm and taking 1 gram off the hammer you will achieve approximately the same goal as moving the knuckle to 18 mm (maybe a little better in fact). You won't have to compromise jack angle either. To figure out how much lead you can remove it is 1:1 inverse ratio FW: BW. So if you want to add 6 grams of balance weight you subtract 6 grams of FW. (Makes sense, right? You take lead out of the key and the touchweight gets heavier.) That's a 12 gram lead located in the middle of the keystick (between front and balance rail). Don't get too hung up on 3-2-1-0 configuration. You're slightly better off with a 4-3-2-1 set up with the leads moved closer to the balance rail. As far as determining hammer weights with existing configurations you can always set up your key samples at 80%- 85% of FW max then sample various hammer weights (cut and weigh lengths of solder and then wrap them around the end of the shank) and experiment with different weights until you get the BW that you want (my preference is 37 grams). When you find the hammer weights for your samples that work, plug them into a spread sheet and make a curve using those as guides or just do it manually. Make sure your hammer set can achieve your targeted weights +/- .5 grams. That will put you right on target. You can also go the other way, take your hammer samples from a set and figure out about what the minimum reasonable weight is for those particular hammers with full tapering and go from there with the lead solder to check. Remember that the lower the action ratio the greater the key dip or shorter the hammer blow will need to be. There is a point of diminishing returns. BTW, knowing how much lead is in the keys is easy when you compare front weight maximums to measured FW. David Love davidlovepianos at comcast.net www.davidlovepianos.com -----Original Message----- From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of Farrell Sent: Tuesday, July 03, 2007 1:50 PM To: Pianotech List Subject: Re: Action Ratio and Dip and Blow and Etc. Yes, there is room in the rep lever window to move rearward up to even three millimeters. Take a look at the following photo: You can see that the jack long axis and the knuckle core axis are pretty close to parallel with one another. As you can see, I increased the wippen heel height quite a bit to get the heel/capstan interface on the magic line at half blow - that modification has decreased friction a fair bit. Take a look at the lead in the keys in the photo below: That's where my concern about lead stems from. All front weights are 0.96666 of Stanwood's maximum front weights. All strike weights have been modified to follow the line between the heavy SWs and the medium SWs on the Stanwood SW curves Are you thinking that the slight loss of efficiency at not having the jack perpendicular to the shank at rest will be more than offset by the action ratio becoming more efficient by moving the knuckle out? I've never moved a knuckle before. I've moved capstan lines, but not knuckles. It is difficult for me to understand how moving the knuckle out would increase action efficiency and increase dip for a given blow. I see opposing effects - less efficiency on the shank lever, but increased efficiency on the wippen lever. How does that work? Thanks. Terry Farrell > ----- Original Message ----- >> What is the knuckle radius? >> If you can bump it out to 17 or 18mm >> you can increase the dip and get rid of some lead. > > So you are of the opinion that my dip is undesirably small? How can you be > so smart to know that this action had lots of lead in the keys? ;-) > > 16mm. I'll look to see if there is room in the rep lever window. Getting rid > of lead would be good, I think. I have reduced the lead from six in the bass > to 4-1/2, but that is still a fair bit of lead compared to the ideal of > three in the bass to none in the treble. > >> Maintain about a 90 degree angle between the jack and shank at rest. > > I think it's close to 90 degrees now - I'll look to see how moving the > knuckle out further will affect things. > >> Is the wippen flange centers at a good height? Usually 2 1/2" below the >> HCH. > > I'm trying to imagine what HCH could be - and am failing. What is HCH? > >> Jon > > -------------- next part -------------- An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/20070703/943741ec/attachment-0001.html -------------- next part -------------- A non-text attachment was scrubbed... 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