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MMD > Archives > May 2017 > 2017.05.28 > 02Prev  Next

Artrio-Angelus Tracker Bar Dimensions
By Wayne Stahnke

Several MMD subscribers have shown an interest in Artrio-Angelus rolls
and instruments lately, so I thought it might be useful to share some
measurements of Artrio-Angelus tracker bars that I made a while ago.

I started scanning Artrio-Angelus rolls, and reconstructing the punch
matrices for them, in late 1996, shortly after completing my optical
scanner and punch matrix reconstruction program.  The fact that some of
the perforations near the left edge of the roll are not on 9-per-inch
centers caused some difficulty, which I circumvented by examining the
scanned image to estimate the offsets of the unusually-placed ports
from their expected positions.  This is far from ideal, of course; it
was a stopgap measure that allowed me to proceed with the scanning that
I was doing at the time.

In 2003 I decided to determine the spacing more accurately.  To that
end, Dave Krall loaned me three tracker bars.  Two were Artrio-Angelus
tracker bars, one built by Wilcox and White and the other by Simplex.
The third was a Duo-Art tracker bar.  We have Dave to thank for making
it possible to determine the dimensions given below.

I did not have the equipment to measure the dimensions accurately, so
I contracted with a local machine shop to take the measurements in
their inspection department.  I was worried that the tracker bars
might have grown or shrunk over the years, so instead of using the
measurements directly I used the Method of Least Squares to create
a best fit over tracker bar ports known to be on 9-per-inch centers.

With this done, I was able to calculate the offsets of the first four
ports on the left and the Melodant ports (Wilcox and White's name for
the theming ports) from their 9-per-inch positions.  I sent the results
of my investigation to Dave in an email dated October 6, 2003, which
appears below.

I am happy to provide anyone with the original measurements and the
program I wrote to determine the offsets, if someone wants to check my

Wayne Stahnke

 From: Wayne Stahnke <>
 Date: Mon, 6 Oct 2003 13:31:32 -0700 (PDT)
 To: Dave Krall <>
 Subject: Tracker Bar Dimensions

Hello Dave,

I have completed my investigation of the dimensions of your
Artrio-Angelus tracker bars.  As I mentioned in our telephone
conversation, I had the tracker bars measured by the inspection
department of a local machine shop.  I then wrote a computer
program to combine the resulting measurements in an optimal way
using some sophisticated statistical ideas.

In order to present the results of my investigation, we first
need to define some terms:

(a) I call the theming ports the "Melodant" ports, because that
is what Wilcox and White called them.

(b) I number the port positions 0,1,2,...,99 counting from bass
to treble.  Note that the bass Melodant port actually occupies
positions 4 and 5 (approximately), and the treble Melodant port
actually occupies positions 94 and 95 (approximately).

(c) I call the "uniform position" the centerline of a given port
on a 9-per-inch scale.  Note that the uniform positions of the
Melodant ports do not fall on multiples of 9-per-inch but rather
halfway between two of these, because these ports have double

(d) I call an offset toward the treble side a positive offset,
and an offset toward the bass side a negative offset.

With these definitions out of the way, I am prepared to present
my results.  Here they are:

(1) The centerlines of ports 0, 1, 2, and 3 are offset by -0.042
inch from their corresponding uniform positions,

(2) The centerline of the bass Melodant port is offset by -0.015
inch from its corresponding uniform position,

(3) The centerlines of all other ports are identical to their
corresponding uniform positions.

Thank you for loaning me the tracker bars for this measurement.
I enjoyed working on this interesting and important effort.


(Message sent Mon 29 May 2017, 02:03:50 GMT, from time zone GMT-0700.)

Key Words in Subject:  Artrio-Angelus, Bar, Dimensions, Tracker

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