Action Ratio and Dip and Blow and Etc.

[Farrell]

Hi David. Thanks for your input. I have a couple questions about hammer mass with Del-designed bellies. I did some experimenting with note #40. The picture you are referring to was actually note #16, not #20 - but that doesn't really matter. You are suggesting a SW for note 20 of 9g or maybe even a little less. That's a light hammer! But then, your reasoning may be right on, considering the new efficient Del-designed belly in this piano. 

Do you set your hammer weights using Stanwood's Smart Chart SW curves? A 9g SW for note #20 falls about 2/3 of the way up from the extreme light curve to the light-medium curve. Staying on the same curve, note #40 should have a SW of about 8.0g or 8.1g, according to the Stanwood curves. That curve would have and A0 SW of about 9.5g and a C88 SW of about 4.2g. Is that what you are thinking? I realize, of course, these Stanwood curves are nothing set in stone - a particular piano may do better with a curve that crosses into other zones on Stanwood's Smart Chart. What SW curves do you find working best with Del's designs? What kind of hammers are you favoring? Probably a Ronson. With what kind of felt?

Note #40 originally had four 12g leads in it. I put a 17mm knuckle and an 8g SW hammer on - popped out the two leads closest to the key front and measured DW - it is now less than 50g. If a light SW range works well for this piano belly, it would seem my problems are pretty close to over. 

Part of my initial confusion may also be related to info on the Abel shank/knuckle data. They offer two shank/knuckle/flange assemblies for old Knabes - their data indicates that one has an 18mm core-to-center distance, and the other is 17mm. The shank assemblies I received from Brooks have a 16mm distance. I'm not sure why. I'll give Wally a jingle on Friday.

Terry Farrell
  ----- Original Message ----- 
  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. 


  SNIP

  David Love
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