What's the best material for an upper plate bridge bearing rod ?

[pianoguru at cox.net]

---- "Prof. Euphonious Thump" <lclgcnp at yahoo.com> wrote: 
>I presume they used it because it's  a harder
> sort of steel, and they wanted a  definite,
> long-lasting termination point, but it still developed
> little nicks in it from the strings.

The degree of hardness of the termination is a controversial question.  Some like it hard, some like it not so hard.  The hardness of the termination material is not the same as the rigidity of the termination.  One extreme case of hardness of the termination is Baldwin's termination piece in the SD and SF series.  In this case, I do not like what it does to the sound.  For this reason, I tend to go with the more traditions "not so hard" material.  Brass agraffes and non-hardened v-bars have worked well for a century or so, and perform better, IMO, than tungsten termination pieces.

>I want to get a bit more bearing on the
> tenor/treble bridges, by either A) Replacing the rod
> with a  smaller diameter: in which case I'd like some
> advice about the type/hardness of steel/or other
> material I should use.

To alter the thickness at the top termination of the speaking length will gain you a lot at 88(where you probably don't need it), but next to nothing at the bass end of the treble bridge.  If you need more down bearing, it is probably more at the middle of the treble bridge, and this can probably be done more effectively at the bridge termination.

> Which raises question #2: What sort of
> string-to-bridge angles should I want on an unstrung,
> massive ( 57" ) upright, with no soundboard cutoff
> ?????

I am glad to see that you recognize that the important dimension regarding down bearing is the angle of string deflection.  For too long down bearing has been specified in linear dimensions, since angles were too difficult to measure accurately (before the Wixey angle gage came along).  Others will disagree with me, but I prefer to have the total down bearing divided equally between front and back bearing.  For a large upright, I would like the total down bearing angles to be 0.3 degrees at note 1, 0.6 at the last bass note, 0.5 at the lowest treble note, 1.0 at the middle of the treble bridge, and 0.7 at note 88.

Frank Emerson