geometry -- knuckle size

[Richard Moody]

Dear Puzzled. 
	Since the knuckle sits on the jack, a decrease of 1 mm in the  diameter
of the knuckle is the same thing as shaving 1mm off the bottom of the
knuckle.  Or how much shorter is a 9 mm knuckle than a 10 mm knuckle? So
taking 1mm off the knuckle would lower the hammer by seven times that
amount, if the ratio of the hammer to knuckle to shank pivot, (flange
center pin) is 7 to 1.

You asked
>	Doesn't increasing the knuckle diameter really only
> increase a given point on the knuckle 1/2 of the diameter increase??  

If you increase the diameter of a knuckle by 1 mm the diameter increases
by 1 mm.  If you increase the RADIUS by 1 mm the diameter increases by TWO
mm.  

Sir Jim Bryant also writeth......
>  As for changing the after touch, by changing knuckle size, >don't most
things
> we do affect the after touch in some manner? 

I don't see the logic of changing knuckles to change after touch, 
Certainly after touch might be affected by a change in size. But the most
striking and first observed change in knuckle size would be hammer
heighth. This is usually adjusted by the capstain. Unless you changed back
rail felt at the same time...... 
	So here is a multiple choice question..... If one screws up the capstan
to raise the hammer by say 2mm what will happen to the after touch?
A.Increase. B. Decrease. C Remain the same.D all of the above.E none of
the above. 
Here is an essay question. "Explain your answer to the above question." 

OK here is another question. 
	Replace a knuckle with one 1mm in dia larger.  What will happen to the
after touch?  A. Increase  B. Decrease. C.Remain the same. D. All of the
above. E. None of the above. 


Ric E. Hintsome
 



----------
> From: JIMRPT@AOL.COM
> To: pianotech@ptg.org
> Subject: Re:  Re: S & S 'A' parts, geometry -- shanks and flanges
> Date: Wednesday, October 07, 1998 7:54 AM
> 
> Et Al, and RicMcEngeneer;
> In a message dated 10/5/98 3:43:49 PM, remoody@easnet.net wrote:
> 
>Or 1 mm increase
> results in a 7 mm increase. If the knuckle flattens out by 1mm subrtract
> 7mm.">>
> 
> Is this really true?? Doesn't increasing the knuckle diameter really
only
> increase a given point on the knuckle 1/2 of the diameter increase??  
> 
>  As for changing the after touch, by changing knuckle size, don't most
things
> we do affect the after touch in some manner?  As all, or almost all
points are
> regulatable on the action I think the only nonregulateable point
affected by
> larger/ smaller knuckles is the window in the balancier rail.
> (I know you can shave jacks and mortise windows but these are
modifications
> and not regulation IMHO)
>   Or am I missing something fundamental here?
> Puzzled.
> JIm Bryant (FL)
>