Hello Paul:  You have a lot of questions and I will attempt to answer
them clearly.

> 1)  Can anyone in the MMD enlighten me as to how the reed voicers
> at Wurlitzer managed to work out how much lead loading to attach
> to the reed tongues, and what method of attachment did they use?

1) The Willis weights were determined by empirical methods of the day.
Being that the organs were mass produced, the tongues were cut and
curved by people on the production line.  The weights were precut also
and arranged in order of weigh to be attached to the tongues.

Surprisingly, many ranks of reeds were shipped that never were touched
by a voicer, as the tolerances obtained on the line worked quite well.
Today if a weight is missing the simple formulas used in beginning
physics courses can determine the amount of weight needed.  You have
to know the spring force of the tongue and this can be measured with
a scale.  Then you apply the formula for simple harmonic oscillation:

  fo = (1/2pi) x [square root of (k/m)]

where fo is the frequency of oscillation, pi is 3.1416 as always, k is
the spring constant, and m is the mass.  Mind you, the mass of the
tongue is not the whole tongue but the part that moves below the tuning
wire contact.

> 2)  How did they control the heat so that the tongues didn't warp or
> buckle?  What happened if they put to much on?  Did they just melt
> it off again?

2)  The tongues that had brass weights soldered on did not warp enough
to cause any problems, and upon cooling down from the relatively low
soldering temperatures they returned to their original shape nicely.

Where only lead solder was used, if too much was added, a quick draw
of the knife took off some of the solder blob and the tongue was
tested.  Even the solder amounts were just cut from normal round solder
and simply weighed previously for production.  It was close enough to
be called semi-precise!   ;-)

> 3)  The reason for asking is that I am currently restoring a model
> 260 organ made for the Plazer Piccadilly London, a Paramount flagship
> cinema in 1926.  I believe it was the first Wurlitzer installed in
> this country to rise up on a lift.

3)  The Wurlitzer Style 260 is one of their best models,
congratulations!

> 4)  I'm currently working with a voicing colleague, regulating and
> adjusting the speech of the reeds and flues, and as a matter of course
> raised the above questions.  Here in the UK it's common to find tongue
> loads made of felt or lead, or both, attached with chats (Chattertons
> compound), a kind of tar product that glues felt or lead to brass, and
> I have never encountered blobs of solder direct on the tongues.

4)  The solder was precut and measured then simply melted onto the
tongue.  The tuning wire range left some latitude for error.

> 5)  Incidentally what are the reed tongues made of?  The shallots
> are brass, but the tongues look like phosphor bronze, or was it some
> other grade of brass?

5)  The tongues are made of hardened phosphor bronze which is called
grade A, and are tempered to give a STG rating of about 7.5 to 8.5.

Please note that most Wurlitzer reed problems are the result of the
dimensional instability of the brass shallot and NOT the reed tongue.
Check first the flatness of the face of the shallot and true file it
if necessary.  I use an optical flat.  When not flat, machinists dye
applied to the face of the shallot will tell where the high and low
points are with an initial run on a first rate quality file.

The reed tongue is usually the last thing in a Wurlitzer reed to check,
and when there's a problem most commonly the reed tongue has developed
a flat spot where the tuning wire has been run up and down.  Recurving
the reed tongue in a reed vise will not always help, and sometimes the
reed tongue will need to be cleaned off and reversed with a new curve
in the opposite direction to give another 70 years of service!

I buy reed tongue stock from a local dealer in flat sheets so this is
still available, though the metal specialist wouldn't recognize what
a reed tongue was.  Order "Grade A phosphor bronze RI of 30T", with a
hardness of 78, in sheets by thickness in mils (or thousandths in the
U.S.).  It is not cheap, but it is less expensive than the organ
suppliers charge.

Good luck to you on your restoration.  I was a member of the
installation and restoration of the Publix One in the Berkeley
Community Theatre.  We won an award from the ATOS for our first class
work and I will have to tell you that crew chief Bill Schlotter stopped
counting at 65,000 man-hours of work.  I believe that figure has been
doubled since then.

Best wishes,

Al Sefl