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Subject:
From:
Phillip Allen <[log in to unmask]>
Reply To:
Harpsichords and Related Topics <[log in to unmask]>
Date:
Mon, 20 Nov 2017 17:31:55 -0700
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The Spiral Pitch: John Larson & Peter Bavington have suggested that it is
the pitch of the spiral causing problems.  I have to admit I wasn't
monitoring the pitch carefully.  I just happy that I could spiral it down
the wire and keep it tight!  I have copied an updated string list including
the original pitch and 4 measurements of my pitch.  Mine were all at least
1/2 of what they should be, too dense/tight.  I have spent this afternoon
making 3 more strings striving to get a 2mm pitch.  The first one I was
able to tune up to pitch (F#) without a hitch and the pitch is 2mm!  The
second, tuned up to almost F# and then broke.  Measuring this bad 2nd
string I noticed that the pitch was closer to 1.5mm.  For the 3rd string I
took the piece of leather that I was pinching the Cu-wire to apply tension
with and made 2mm marks along the edge so I had something to eye-ball up
the 2mm spiral better.  The 3rd string also tune up to F# without a
problem!  So I think my entire problem was too close of spirals.

So how do the professionals manage to spiral exactly 1.5mm, 2.0mm, 2.5mm or
3.0mm pitches?  Is there a trick or just practice like hand-cut dove-tails?
Peter: Do you have a reference that I can look up to perform the tension
calculations myself?  I am a geochemist so the math sounds interesting.

My Two successful splices:  I George Debono & Michael Dunn:  I managed to
make a small hitch-pin loop on the broken end of the old string, to the
right of the bridge and another hitch-pin loop on a short section of 0.018"
wire.  Then I just slipped the loop over the other loop and fed the end
through the other's loop and pulled tight to make a sort of square note.
My proper piano-wire square knot tests didn't really hold up too well.
These splices don't look nice and I am not sure they will last the week but
lets see!  I like your comment about soldering the twisted wire together.
I will give that a try next time after I re-wind some more strings with
broader spirals/pitch.


Tomorrow I will try to make a few more.  If my girl friend is still willing
to turn the crank!

Thanks for the suggestions and I will keep the list informed of my progress
in the following days.

Phil

String #Note #1 Speaking Length_1 Yellow_Brass_Core  Cu_Wrap  Spiral Pitch
Winding Angl     Pitch_MY_WIRE
   1       C           1097             0.016         0.016
0.079”/2.0mm            50     0.041”/1.04mm
   2       C           1097             0.016         0.016
0.079”/2.0mm            50
   3       C#          1082             0.016         0.016
0.091”/2.3mm            46
   4       C#          1082             0.016         0.016
0.091”/2.3mm            46
   5       D           1069             0.016         0.012
0.055”/1.4mm            57     0.033”/0.8382mm
   6       D           1069             0.016         0.012
0.055”/1.4mm            57
   7       Eb          1054             0.016         0.012
0.063”/1.6mm            54
   8       Eb          1054             0.016         0.012
0.063”/1.6mm            54
   9       E           1038             0.016         0.012
0.071”/1.8mm            51
   10      E           1038             0.016         0.012
0.071”/1.8mm            51
   11      F           1022             0.016         0.012
0.083”/2.1mm            47
   12      F           1022             0.016         0.012
0.083”/2.1mm            47
   13      F#          1007             0.016         0.012
0.098”/2.5mm            42
   14      F#          1007             0.016         0.012
0.098”/2.5mm            42     0.024”/0.6096mm
   15      G           986              0.016         0.012
0.118”/3.0mm            36
   16      G           986              0.016         0.012
0.118”/3.0mm            36
   17      G#          968              0.016         0.010
0.051”/1.3mm            56
   18      G#          968              0.016         0.010
0.051”/1.3mm            56
   19      A           948              0.016         0.010
0.063”/1.6mm            51
   20      A           948              0.016         0.010
0.063”/1.6mm            51
   21      Bb          923              0.016         0.010
0.079”/2.0mm            45     0.026”/0.66mm
   22      Bb          923              0.016         0.010
0.079”/2.0mm            45

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