I did a glass-working course in my
final undergraduate year (1981-1982); and in the research lab where I
did my final-year project there was a town-gas (mostly methane) and
oxygen burner used for fixing-up vacuum lines, etc.. So, for practice,
I took to raiding lab rubbish bins for broken Quickfit (ground-joint
borosilicate) glassware; and during the long boring periods of waiting
for spectroscopic scans to complete, I salvaged glassware parts and
welded them together to make usable items. These were mostly things
like separating funnels, still-heads and vacuum adapters. Hand
annealing was the only option, and so some of it cracked where I had
welded too close to cones, sockets and stopcocks; but a lot of it was
fine, and I still have some perfectly serviceable pieces.
In 2013 to 2014, I became
interested in vacuum systems again; this time for the purpose of
using the ionisation of low-pressure gas to reveal the standing-wave
patterns on helical transmission lines. That work was self-funded
however, and I somehow seemed to have developed a powerful aversion to
prices that science equipment suppliers ask for vacuum-system
components. The general solution, of course, would have been to revive
the art of the glass
vacuum line, which is cheap and cheerful, and has the advantage that it
doesn't conduct electricity.
There is however more
to making a vacuum line than welding bits of glass tubing together. It
is a collection of components that includes traps, gauges, valves,
stopcocks, ports and receiving chambers. Thus a certain manufacturing
capability is required beyond the possession of an oxy-propane torch,
and this led to an interest in glass lathes. Such machines are
rare, fabulously expensive, and much sought-after; but they are not
particularly complicated, and making one is not beyond the capabilities
of a small workshop equipped with a lathe and a milling machine.
of home-built glass lathes can be found on the web, but most designs
are based on the metal-working lathe. This is a workable but not
approach. About the only thing that a glass lathe has in common with a
metal lathe is that the workpiece is rotated about a horizontal axis.
After that, there is no great similarity. A glass lathe is an
anti-gravity machine, allowing molten glass to be worked without
sagging. Its typical rate of rotation is about 1 revolution per second.
There is no need to apply any torque to the workpiece, which is held
lightly in a soft-jawed chuck. Most versatility is obtained if
large diameter tubes can pass through the chuck, which means a large
The basic operation performed by a
glass lathe is that of
joining co-axial tubes. This requires two chucks rotating in
synchrony; one fixed horizontally (the headstock); and one moveable on
a sliding bed, or on rails (the tailstock). Traditional designs have
the chucks synchronised by means of belts and a drive shaft, with the
ability to disengage the tailstock drive in the event that only one
chuck is needed (see Edwards G3 diagrams below). Separate chucks driven
by stepper motors is a more modern option that sidesteps a great deal
of mechanical complexity.
Dual spindle glass lathe
Lindsay Wilson. Home built glass lathe + collected photographs of other
examples + useful links.
. Rail-based construction for
Tubecrafter. This design recognises the need for a large throat in both
lathe chuck using worm gears
- Dalibor Farny,
Nixie tube maker.
- Dalibor Farny
Glass lathes on Alibaba
Glass lathes on Indiamart
Laboratory Glassworking for Scientists
A J B Robertson, D J Fabian, A J Crocker, J Dewing, Butterworth 1957.
Chapter 6 (p97-101) gives a description of the Edwards G3
. Figs. 34 and 35 from the book are
DWK's ideas on
constructing a glass lathe
while experimenting with
various methods for visualising EM field patterns around solenoids(Jan
In 2014, I bought an Edwards
2-stage rotary vacuum pump, and found that I could get a decent low air
pressure using regular Quickfit held-together with vacuum grease and
pumped via Viton tubing. This opened the way for complete visualisation
of the field around a resonating solenoid, by putting it in an
evacuated bell-jar and ionising the residual air. This largely removed
the need for glassworking on my part, and while I continued to
put-together a glass workshop in a covered outdoor area, this was
perhaps a project that was going nowhere.
For partial field visualisation, I'd
already had some Sign tubes made by Neon Creations, and I discovered
that I could use a Germicidal Hg-Ar tube in a Lee 226 filter sleeve.
Later, I was also given some straight He and Hg-Ar spectrum tubes made
by Peter Jameson, and an electrodeless Hg-Ar tube.
Solenoid Field Visualisation
Germicidal Tubes and the Lee 226
Peter Jameson's Tubes
Making an ornamental vase
Valley Glass Works
2014). The glass billet, heated to
a viscous state, has been attached to the end of a thick-walled steel
The billet is initially rolled on a steel plate to form a
bulb. The bulb can be blown through the tube if a hollow item
required. The tube is then rolled backwards and forwards on a pair of
steel rails, to give a lathe action, occasionally reheating it in a gas
furnace to maintain viscosity, while the item is shaped using a
heat-proof pad and various steel tools. Once finished and
cut from the tube, the item is subjected to a slow annealing process
involving a series of progressively cooler ovens.
2021 June 22nd