One of the things one sometimes has to do when glassblowing by hand is
to force air into the tube. In my extremely limited experience, this was
done with a cigar holder attached to one end of a rubber tube and the other
end of the tube attached to the glass, with corks used to stop up other
openings in the glass. You can use the air pressure to keep the glass
from collapsing or to force it to expand outwards, depending on one's
need. I think that arrangement would be a little awkward with a glass
working lathe. Does the lathe chuck have a feature that allows air to
be forced into the rotating glass tube?
--
Ignorantly,
Allan Adler
* Disclaimer: I am a guest and *not* a member of the MIT CSAIL. My actions and
* comments do not reflect in any way on MIT. Also, I am nowhere near Boston.