I do a (very) little scientific glassblowing, as do a couple of my colleagues. It was suggested that, since the department would never be able to afford a glass lathe, building one (or having one donated to us) would be the only way to get one.
For those who haven't seen 'em, a glass lathe has two spindles with 3- jaw chucks lined with ceramic cloth. The spindles are geared together to turn at the same (slow) rate, so the glass doesn't twist. The setup allows one to heat one part of a glass tube evenly, all around the circumference. Great for sealing large-diameter tubing together and lots of other operations.
The ways, two headstocks, spindles etc. aren't a serious problem---I built a Gingery lathe years ago---but the chucks must have a very large through hole. 3" wouldn't be too large, 2" would be ok.
High precision isn't necessary, so I was wondering whether it would be possible to get a couple of cheap 8" chucks, remove the jaws, and bore out the center to, say, 3" or more. Of course, the center of the scroll would be bored out. Would that affect general operation of the chuck? (I thought that if the gearing was on the outside of the scroll, the thing should still work. I might be full of it. It wouldn't be the first time; just ask my wife.)
Thanks! -- Terry