When it rains it pours.  A week or so ago I took some previously
mentioned [120703 MMDigest] large format drawings of Welte (Licensee)
drawings from an original service manual to my local graphic production
house to have them digitized in anticipation of being able to take
orders for copies at the upcoming AMICA convention.  Imagine my surprise
when I went to pick up the digital files and a few "proof" copies to
discover in with the mix there was an actual blueprint (white on blue)
of a drawing bearing the date 1921 which shows not one, but _two_
"Transforming Bars" of the type being recently discussed.

The original drawing itself, which I had not realized was in the package
containing the other drawings is very faint, fragile, and will probably
have to be entirely re-created, however, here are some initial details.

The drawing title block shows the following information:

  Welte Mignon
  Reproducing Piano
  Outlined by George A. Abeel (or possibly Abgel)
  Drawn and Traced for the
  Danquard Player Action School
  By J.H.G. Miller 1921

Although it is not specifically labeled as a grand or upright
configuration, the placement of the various components suggest an
upright lay-out.  The tracker bar(s) shown are of the type having
a vertically oriented slot below and between the first and second
tracker bar holes which is used to trip the re-play pneumatic.  Also,
the "Pressure Regulating" pneumatics shown (last point of control
before entering the stack) are of the type having a hinged pallet
valve serving as the regulating or "choking" device.

Now it starts to get a little confusing.  Prominent in the center
of the drawing is a depiction of the so-called "transforming bar"
shown schematically as a long rectangle with curved ends, sort of like
a racetrack except the end lines are only about a 90 degree segment of
a circle, not 180 degrees.  Whether this is an accurate representation
of the actual part is unknown.  This feature is clearly captioned as
"(Former Type)".  It is probable that the "1921" date in the title
block refers only to the vintage of the drawing itself and not to the
vintage of the component design or lay-out.

In another part of the drawing, a somewhat simplified alternate
configuration is shown.  It is depicted as having a true rectangular
design with 90 degree corners.  Oddly, its caption labels it as
"Transforming Bar Later Type (1920)"

Pending further analysis, I will associate the "Former Type
transforming bar" with the pallet valve style regulator and the "Later
Type transforming bar" with either late production of the pallet valve
style regulator or early production of the knife valve style regulator.
At some point, the "transforming" function was reduced to the relatively
simple rotating switch shown in the "Auto Pneumatic Action Co."
drawings which also show the knife valve regulator.

This still leaves open to question what style of "transforming bar" would
have been used with the even earlier "tapered plug" style regulators.

I am sending Robbie two files showing the salient sections of the
blueprint.  They are a little difficult to read but should suffice
until some pixel editing can be performed on them.  I will have a
slightly reduced size copy of the entire blueprint, as well as the Auto
Pneumatic Co. drawings (grand and upright) available for inspection,
with me at the AMICA convention in Pittsburgh next week.

John Grant
reddawg@unameit.net.geentroep [delete ".geentroep" to reply]

 [ Thanks, John, I will put the drawings under "Welte-Mignon" at the
 [ MMD Tech site, http://www.mmdigest.com/Gallery/Tech/index.html 
 [ -- Robbie