I have been buying the smaller sizes of tubing from Schaff Piano
Supply. I have not been disappointed.
The tubing is uniform and quite supple. The tracker bar tubing
(9/64") comes in two wall thicknesses, 1/32" and 3/64". The
Expression sized tubing (3/16") is the best I've ever used.
The thinner walled tubing works great for early Aeolian systems
where the tubing has to pass though numerous pre-drilled passages.
I also prefer the thinner walled tubing for Simplex systems and
all transposing tracker bars.
The thicker-walled tubing works great for modern Aeolian products
such as the Sting, Sting II, Cabaret, Duo/Art, Musette, Keepsake
and Pianola. In the above systems, the tubing is forced to make
somewhat sharp turns as it passes through the keybed. The thinner
walled tubing has a tendency to collapse when used in such a
situation, whereas the thicker walled tubing is more resilient
to 'pinching'. At this point in time, I've yet to have to replace
the transposing tracker bar tubing in any of the modern Aeolian
John A. Tuttle