S & S 'A' parts, geometry -- shanks and flanges

[Richard Moody]

List Newton 
	I came up with 1/7 ratio for rise of knuckle to rise of hammer. 
	So.....Increasing the knuckle diameter by .05 " (.1.25mm) will cause an
increase in hammer height of almost .350 " ca 11/64 +.    Or 1 mm increase
results in a 7 mm increase. If the knuckle flattens out by 1mm subrtract
7mm. 

For calculations see below. If there are incorrections or errors please
post and or email. For drawings send sase and $100 per hour for engineer
consulting fee. Since I am not an engineer nor a student make that $10 an
hour.  What a bargain. 

Ric Inthe Bar'gain   


Increasing the diameter of the knuckle by .05"  (five hundreths of an
inch)  (1.27mm)....thats about the equivialnt of the thinnest felt or
thickest cardboard balance punching. (btw 1 mm is close'nuf to .4 in.)  
(1mm = .03937 in)       
	The first effect would be to raise the hammer....... um how long is the
shank from knuckle and how far from the pivot point is the knuckle?
	From actual size drawings from an Asian supplier, (for their Steinway
flange and shank) it looks like 17 mm from center line of knuckle to
center of flange center pin.   The knuckles measure 10 mm. (.393).  From
center line of knuckle to center line of hammer I guess (they don't show a
hammer on the shank) 123 make it 120 to be conservative. So we have a
17/120  ratio.  or 1 to 7 plus a  hair.    So my guess... increasing the
knuckle diameter by 1 mm would raise the hammer 7 mm.  Increasing to 1.25
would give 8.75mm.   Egads, that's a lot. 
	Well the knuckle isn't raised straight up, it is actually going in a
circle. But I will leave that to a college undergrad engineer student to
figure out, and assume it won't matter more than a whopping one mm.   
	I did try to confirm with a hammer shank flange assembly and washer, and
came out close enough to get into the Astro Dome.  rm  

an interpolation reference....

Knuckle 17mm from C pin  hammer center 125 from knuckle = 1/ 7.35  

Knuckle 17   hammer 120 =1/ 7.05

Knuckle 17  hammer  115 =  1/ 6.76
	
Knuckle 17.5  hammer 120 = 1/ 6.86

----------
> From: Newton Hunt <nhunt@jagat.com>
> To: pianotech@ptg.org
> Subject: Re: S & S 'A' parts
> Date: Monday, October 05, 1998 9:39 AM
> 
> OK, just for fun think what would happen, throughout the action, if the
> diameter of the knuckle changed from .360 to .420 or more.
> 
> Then think what would happen, just for the fun of it, if the knuckle,
> engorged, moves toward the center pin 2mm or so.
> 
> The knack serves as the lift point of a lever.
> 
> Let me know when you have some results of your thinking since this is a
> physics examination and you are expected to hand in your drawings and
> calculations.
> 
>         Newton
>