I have not received the posting from Mark Singleton, and I cannot find
in the Archives yet, so cannot comment on it.

First of all, restorers of musical boxes receive the movements with
combs damaged, rusted, missing teeth, corroded or completely gone
leads, tip wear, or already re-tuned in the past, so not all combs
have a reliable original tuning.

In all the years that have restored musical boxes, I now have two big
folders full of tuning scales in absolute numbers (Hz) which can easily
be re-written in the more usual musical notation if someone wants it.

One folder is for disc boxes but that only grows if a disc box comes in
which is not already on file.  The folder for cylinder music boxes has
now become very large and has scales from the earliest stacked comb
movements from pre-1810 to probably the latest from circa 1910.

I have no idea what will happen with the folders when I am no longer
here; the scales are in my difficult-to-read handwriting and will
probably end up in the old paper bin.

When Kevin McElhone asked me to contribute scales to his book about
disc boxes I suggested to note the scales with the measured stretch
(lower or higher) for that note.  That proved to be too much data to
publish, so it ended up with only mentioning the 'A' for that scale.

But here is data from an original tuning found on 62.5 cm Polyphon;
UC = upper comb, LC = lower comb.

First upright machine.
UC, tooth nr. 30/31 = 440/438 Hz.
LC, tooth nr. 29/30 = 435/435 Hz.

Second upright machine.
No 'A' in upper comb
LC, 'A' = tooth nr. 33 = 441 Hz.

Folding top machine.
UC, tooth nr. 32/33 = 432/435 Hz.
LC, tooth nr. 33 = 440 Hz.

I will not comment on them but most likely if you check more movements
you will find even more differences.

For other size Polyphons I have most A's are somewhere around 435 Hz,
but the lowest on record is 426 Hz and the highest is 450 Hz, and that
last one is of the earliest cardboard disc type.

Combs have a hardness from around 35 Rc.  You can of course make them
harder and get a brighter tone, but apart from the increased risk of
breakage you must keep in mind that the 19th century makers only had
basic tools to work the hardened and tempered comb.  They did not have
diamond tools to bring the tooth to the final dimensions only normal
files, which have a hardness of around 50 Rc and which does not "bite"
on harder material.

Also -- and this is especially for cylinder box combs -- when the steel
is hardened it will distort.  We now have special steel which distorts
very little or not at all, but long ago they had only "simple" carbon
steel and that will go bananas when you harden it!  They had to correct
every tooth placement -- left-right and up-down, within very close
tolerances -- by hammering with the risk of breakage.  The harder you
leave a comb the greater the risk of breakage becomes.

When combs are soldered to their base, which is normally made of brass,
the difference in expansion coefficient will distort the flatness of
the comb so you will have make it flat again using considerable force.
That is why the thickness of the steel plate itself is only around 3 mm;
if you make it thicker you will not easily get it accurate flat again.

Early combs were not soldered together but were riveted or screwed or
whatever other method used, but the comb steel base was much thicker
to make these methods possible and probably also to make sure the sound
transport was the best possible.

Other makers used a steel base to minimise distortion and in later
movements you get those weak white alloy comb bases, which also will
not create very much distortion when you solder the comb steel to it.

Niko Wiegman
The Netherlands
n.wiegman@planet.nl.geentroep [delete ".geentroep" to reply]