Shanks parallel to strings

[Phillip Ford]

>Hello Phil,
>
>Providing the hammer molding is perpendicular to the
>string plane, the force on the string is F*cos(A). "F"
>is the force which is theoretically available if the
>hammer molding and the shank are perpendicular, and
>"A" is the angle between the shank and the string
>plane.
>
>The formula says that the force is maximized when the
>shank is parallel to the string plane.

How did you come up with that formula?

As I see it, the hammer assembly is given a certain momentum by the 
action.  The string provides a resisting force which decelerates the hammer 
assembly.  I can imagine that that force might be different if the hammer 
wasn't striking square, since the contact area might be different than if 
striking square, the hammer might be slightly softer off the tip than on 
the tip, the hammer molding might be bending slightly more or less from the 
applied resisting force, etc.  But I have trouble seeing how the angle that 
the shank makes to the hammer has any effect on that force.


>In addition, if the shank and hammer, and the hammer
>and string plane are not perpendicular, there is
>actually a wiping motion between the hammer and the
>string.  This motion is always there when the string
>deflects, but it is minimized with the 90 degree
>angles.
>
>Vladan

I would think that there would be a wiping motion in any case.  The tip of 
the hammer is traveling in an arc about the hammer flange center.  At 
impact it is not moving perpendicular to the string, even if the hammer 
molding is perpendicular to the string.  There is a component of the 
displacement along the string.  As long as the strike point is the same I 
don't see that the angle of the hammer molding to the string affects 
this.  What's determining it is the distance of the strike point to the 
hammer center and the angle that this forms to the string, not the angle of 
the hammer molding to the string.  And I can't see that the angle of the 
shank to the molding has any effect on the direction of travel of the tip 
of the hammer.

Phil Ford


>I would like to revisit the idea that shanks should be
>parallel to strings at hammer contact.
>...
>Any thoughts?
>
>Phil
>