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Re: Counterbearing angle
----- Original Message -----=20
From: Overs Pianos=20
To: pianotech@ptg.org=20
Sent: March 27, 2001 1:57 PM
Subject: Re: Counterbearing angle
They are easily
shaped if needed and -- depending on the exact alloy -- can approach =
the
hardness of mild steel while retaining the lubricity of brass.
For pianos in commercial service (and tuned perhaps 4-5 times per =
week), say an auditorium which is used daily for broadcasts or major =
recording projects, the 'easily shaped' part is perhaps a bit of a =
worry. If it is easy for the technician to shape the capo bar, it =
follows that it must also be easy for the piano wire the cut the capo =
bar to shreds, doing its 'cheese cutter' thing.=20
Well, as I said, the stuff is about as hard as mild steel. What I mean =
by "easily shaped" is that if need be you can easily shape it with a die =
grinder and a carbide burr with the thing clamped in a vise. You can =
then dress it up nicely with an abrasive grinding disc. Hardly the kind =
of thing the average technician is going to do just before tuning. Nor =
would it be necessary. In my experience the wires show no propensity to =
cut into bars made of silicon bronze so, no, the capo bars are not cut =
to shreds -- again, as I said earlier, the stuff is about as hard as =
mild steel. It wears about as much as a mild steel rod would, which is =
to say, not much. (I've also used that on occasion; i.e., cut a groove =
in the V of the V-bar and inset a mild steel rod. That also works =
nicely.)
Regarding lubricity, our bar-hardened rebuilt pianos have retained =
their easy rendering abilities, when compared to a standard as cast bar. =
When the wire cuts into a non-hardened bar, the bar tends to 'grab' the =
wire to the detriment of string rendering.
I've not noticed any tendency for the strings to cut into a cast silicon =
bronze V-bar. The stuff is hard enough on its own to resist this.
I have designed these into several new pianos, though I don't know =
of any that are still using them -- the manufacturers seem to prefer =
struggling
with improperly shaped and placed (but traditional) V-bars cast with =
the
plate.
Many manufacturers simply 'don't give a damn'.=20
Well, I did have hopes for the one...
Regards,
Del
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