Ho - Early in my day, but let me weigh in on plastic jacis an the
Z-sort in particular.  We're probably said all this before.

Last Friday I went to a college homecoming, to look at the new lab
building being dedicated, and ran into a new visiting prof who, after
showimg me his optical fringe setup, mentioned that he'd once made
a hapchd, a Burton, which since it was his only contact he considered
to be the Definitive Object.  But he did report the usual troubles with
the jacks, which led into an on-the-fly reflection on What Works.

The gist of which was that plastic's a great material; 'tis just not 
the one for which the instrument system was designed.  One could, in 
principle, make a plastic jack _exactly_ like, in mass and dimension, 
a wood one, which  fitted with raven and boar would be indistinguishable
from the "real thing."  One might even be able to enginner and fabricate
a plectrum material of the same fibre-in-a-stroma character as raven, and 
suppress the thermoplastic tendency to change stiffness with temperature.

But the very versatility of plastics makes it near inevitable that the
jack design will get re-engineered, either for convenience of manufacture
or to avoid certain "problems" with plain wood and quill.  Everything 
has tradeoffs.  Thus the modern designs drift away from the character, 
seen as virtues and faults, of the originals.  Quite possibly one might
not so admire the excellences of boar bristle had our times not traveled
thru this territory, from Sperrrrhakkkke and their bone and cast-in 
Burton plectra to the Axleless Z-jack and the convenient snap-in.

I unequivocally like the tapered Z-jacks for most uses.  I can say with
some pride that I've had a Boston player yank off a jack rail to see
how I'd put quill in them, only to find that it was just the usual
Delrin cut with care.  I've had few problems; I recall only two clients
who have played _so_ much that the tongue heads start poppin' off. The
second of those has just called up two ranks of wood from Mr.Purdy, and
one way or another they're about to find their way into use.

The brown tapered plastic, zB, can indeed be induced to warp by wrappin'
hanks of them with elastic bands, or by jammin' the terminal one up 
against a transposed key.  But they're also flexible enough that when
they snag against a slidin' keyboard (and they will) they neither tear
the cloth off the key end, dislodge a lower guide, or just break.  The
floating tongue does indeed waste a little energy, a problem when one
wants to give a bass string a real Whack; but the same loss can be an
advantage in a 4' or a tight-spaced spinet where the lost energy is an
aid to graceful voicing. And - computer folk - the tongues are pretty
much backward compatible, even at $.90 the each.  (I have a bucket
of 'em.)  Their low mass is especially good in the three-register
singles like Herb's;  I just suggested I swap him new jacks for his
old long-tails, which in turn are back-compatible with those awful
early axleless jobbies with the trangle tongue mortices and top screws, 
of which there are a-plenty awaiting replacing.  

Certainly nothing will beat good traditional wood.  My process for
redoing the upcoming big double would not be _en bloc,_ but to redo
the ones which have broken one by each, taking some care to fit the
pluck and balance of the new among the old.  I suspect there will be
a lesson or three to be learnt.  And there was some talk of goose for
them; but my reading is that this player, like most, would really 
prefer not to cope with that added detail; she'd rather play than trim.
I could be wrong.  But I have no special skill with birdies, other than
to approach the effect with Delrin.

And then one recalls last winter's adventure with the Very Fine wood
jacks whose axles had so corroded that the tongues were held rigid
in the grip of a tightly fitted mortice.  Closer examination revealed
that _those_ jacks had originally held quill, which had been replaced
in an unsuccessful effort at rejuvenation by the builder.  Each tongue
bore the stain of applied oil, and his accompanying material suggested
olive, which I think may be rather acid;  the oil, soaking down the
length of the tongue, may well have reached the axle and helped 
catalyze the production of verdigris.  

Everything has its issues.  Jack's complaint that he had to file down
the bulge on the Z jacks at the tongue base suggests to me that another
fault of mass-production is that it promotes the mindset that the 
object will then automatically and mindlessly work.  'Tis seldom so.
A little care is always in order.  I won't be surprised to find that
Mr.Purdy's jacks also require individual attention to details that I'd
have taken care of myself had I been making the things at home.  Plastic's
not the problem so much as lack of care, and inattention to the objective.

There - 12 cents worth of words.

						calhoun


Heisenberg might have tuned here ...