"Oval or Round Shanks"

[Delwin D Fandrich]

Delwin D Fandrich wrote:
> 
> Daleboy@aol.com wrote:
> >
> > dear list,
> >              Who here can say with positive proof that thinning the sides of
> > the shanks is the only acceptable mothod of effecting tone in the upper
> > octaves? Might it not be possible that some additional support for left or
> > right flex of the hammer in that area might be lost by thinning the sides
> > only and thereby losing square hammer to strings contact on harder blows??
> >          Isn't side taper a recent trend?
> > Thanks much!
> >
> > Regards,
> > Dale
> 
> The strength of a beam varies with the square of its height. The
> hammershank is a beam.
> 
> Removing material from the sides of a round hammershank (within
> reasonable limits) has little effect on its ability to transfer energy
> from the jack to the hammer. Taking material off of the top and bottom
> will have quite a large effect. There will be quite a lot more bending
> during a hard blow.
> 
> The best hammershank shape would be one that is rectangular--not round
> or oval--right out to the end where it would have to be made round to
> fit the bored hole in the hammershank. The cross-section of this
> rectangular hammershank, i.e., its width, could be varied as required to
> meet the stiffness requirements of transferring the necessary energy to
> the hammer mass of each note.
> 
> --ddf


(continued...)

In a separate post Doug Richards reminded me that beam stiffness is a
function of the cube of the height. He is, of course correct.

The stiffness of a beam is, indeed, a function of the cube of its
height. Its steady state load capacity is a function of the square of
its height. 

Since what I had in mind was the stiffness of the hammershank, it should
have been "the cube of its height." 

Sorry for the confusion.

--ddf