Is it out of the question to modify Gingery's lathe design to make a
glass working lathe?
--
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.

I doubt you need a machine *anywhere* near as stiff as a metalworking lathe.
Just a slow turning, sealed spindle as far as I know. The only forces
present are bearings, the flame and pressure (plus or minus) inside the
glass, no? And the flame needn't be positioned within thousandths of the
glass surface either.

Tim

--
"I have misplaced my pants." - Homer Simpson | Electronics,
- - - - - - - - - - - - - - - - - - - - - - --+ Metalcasting
and Games: http://webpages.charter.net/dawill/tmoranwms

"Allan Adler" wrote in message
...

Is it out of the question to modify Gingery's lathe design to make a
glass working lathe?
--
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.

I also saw your post on rec.crafts.glass.

Bear in mind that when the glass gets hot, unless both ends of the tubing are
being driven at the same speed, the glass will twist (friction on the "free"end).
A year or two ago, I saw a basic plan that used 2 identical servo (or was it
stepper?) motors to drive the tubing - one at each end. Don't remember the web
site, but a Google search should turn it up; try it on the Google Groups search
first.

What do you want to accomplish that requires a lathe? Most glass work can be done
by rotating the piece with your fingers. It probably would take less time to
acquire that skill than to build a lathe. Of course, if I could get a glassworking
lathe, I'd love to have it...

Joe

Allan Adler wrote:

Is it out of the question to modify Gingery's lathe design to make a
glass working lathe?
--
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.

Allan Adler wrote in message ...
Is it out of the question to modify Gingery's lathe design to make a
glass working lathe?

I wouldn't say it was impossible, but the ones I've dealt with were a
good deal larger, like about 2' swing or better. They also had two
headstocks at the opposite ends with matching chucks and the rotation
of each was synchronized with the other end. This last would be the
hard part without using stepping motors or selsyns. Worm drive with
some sort of speed-sensing control electronics, maybe. HP
requirements would be pretty low, all you are doing is turning the
chuck and workpiece, there's no cutting forces involved. It's been
awhile, but IIRC, the through-holes in the spindles were pretty good
sized. One suggestion for the bed would be to use large steel tubing,
ala Shopsmith, and the same sort of locks for the sliding parts that
are used on it. Except for the chucks and drive train, I don't think
it would be too tough to make up a moderately-sized glass-blowing
lathe.

Stan

"Stan Schaefer" wrote in message
om...
Allan Adler wrote in message
...
Is it out of the question to modify Gingery's lathe design to make a
glass working lathe?

I wouldn't say it was impossible, but the ones I've dealt with were a
good deal larger, like about 2' swing or better. They also had two
headstocks at the opposite ends with matching chucks and the rotation
of each was synchronized with the other end. This last would be the
hard part without using stepping motors or selsyns. Worm drive with
some sort of speed-sensing control electronics, maybe.

The one's I've seen, some very old, just have the head stock and tailstock
geared together with a shaft or with pulleys and shaft -- just keep the heat
away from the belt. As said in other posts, there's very little force
involved and speed is generally quite slow. There are lots and lots of
burners, though; and plenty of steady rests and such.


--

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TEL: 215-572-5580
FAX: 215-886-0144
Email bsquare "at" sprintmail.com

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Well I take if from all the comments that everyone is talking about
taking a piece of fairly molten glass and chucking onto a lathe.

Curious question....... Could you put a cold piece of glass on
a lathe and go from there.

Or am I totally reading this wrong.

How can you all tell I'm just an armchair lurker getting a free
education.

I expect you could take the drive from one spindle to a lay shaft which
ran between or behind the ways to the other headstock spindle so no need
for accurate synchronisation of separate drives.

Stan Schaefer wrote:

Allan Adler wrote in message ...

Is it out of the question to modify Gingery's lathe design to make a
glass working lathe?


I wouldn't say it was impossible, but the ones I've dealt with were a
good deal larger, like about 2' swing or better. They also had two
headstocks at the opposite ends with matching chucks and the rotation
of each was synchronized with the other end. This last would be the
hard part without using stepping motors or selsyns. Worm drive with
some sort of speed-sensing control electronics, maybe. HP
requirements would be pretty low, all you are doing is turning the
chuck and workpiece, there's no cutting forces involved. It's been
awhile, but IIRC, the through-holes in the spindles were pretty good
sized. One suggestion for the bed would be to use large steel tubing,
ala Shopsmith, and the same sort of locks for the sliding parts that
are used on it. Except for the chucks and drive train, I don't think
it would be too tough to make up a moderately-sized glass-blowing
lathe.

Stan

In article , Shiver Me Timbers says...

Well I take if from all the comments that everyone is talking about
taking a piece of fairly molten glass and chucking onto a lathe.

Nope. Glass lathes are designed to allow pieces of
glass tubing, etc, to be chucked up - sometimes from
both ends - and worked with flame while they are spinning.

The 'chucks' are metal fingers that ride inwards, and have
insulating fingers to hold the material when hot.

For example, one could chuck up two different size pieces
of tubing, or tubing of two different materials, one in
each chuck, and effectively weld them together with flame
while they are spinning, so as to maintaine alignment.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

You start out with cold glass tubing and heat and modifiy it from there.

check out a home built one here http://www.repairfaq.org/sam/gwl/

Shiver Me Timbers wrote:

Well I take if from all the comments that everyone is talking about
taking a piece of fairly molten glass and chucking onto a lathe.

Curious question....... Could you put a cold piece of glass on
a lathe and go from there.

Or am I totally reading this wrong.

How can you all tell I'm just an armchair lurker getting a free
education.

--
James P Crombie
Slemon Park, PEI
Canada
Machinist - 3D Cad Design - Amateur Astronomer

http://www.jamescrombie.com

Machineman wrote:

You start out with cold glass tubing and heat and modifiy it from there.

check out a home built one here http://www.repairfaq.org/sam/gwl/

Now I get it.

Thanks for clearing it up and making it as clear as glass.

Tim Williams wrote:
I doubt you need a machine *anywhere* near as stiff as a metalworking lathe.
Just a slow turning, sealed spindle as far as I know. The only forces
present are bearings, the flame and pressure (plus or minus) inside the
glass, no? And the flame needn't be positioned within thousandths of the
glass surface either.

Nope.
I've used a couple of stepper motors duct-taped to a plank, for
joining a couple of tubes.
Worked just fine.

Joe wrote in message ...
I also saw your post on rec.crafts.glass.

Bear in mind that when the glass gets hot, unless both ends of the tubing are
being driven at the same speed, the glass will twist (friction on the "free"end).
A year or two ago, I saw a basic plan that used 2 identical servo (or was it
stepper?) motors to drive the tubing - one at each end. Don't remember the web
site, but a Google search should turn it up; try it on the Google Groups search
first.

What do you want to accomplish that requires a lathe? Most glass work can be done
by rotating the piece with your fingers. It probably would take less time to
acquire that skill than to build a lathe. Of course, if I could get a glassworking
lathe, I'd love to have it...

Joe

Joe, the only glass lathes I've seen were at RCA Sarnoff Labs when I
worked there circa 1956. The characteristic that all of these glass
lathes had in common was a headstock and a tailstock that were both
powered an rotated in the same direction at the same speed. No metal
lathe that I am aware of is capable of this trick.

I have no idea who manufactured these unique machines, but the work
that came off them was truly remarkable and included some fantastic
vacuum tubes, chemical apparatus, and even (under the counter)
Christmas Tree decorations.

Now, 50 years later, I would like to learn about these unique
machines, who made them, and maybe even how I could find one at a
reasonable cost to put in my workshop.

Harry C.

In the 1960's and 70's when I worked as a scientific glassblower, we used
glass lathes all of the time to make 3 stage diffusion pumps etc. The two
most common brands were Litton (best) and Bethlehem (light weight and
cheaper). There were a few other brands available - one nice one made in
New Jersey and several from Germany.

The drive system was always variable speed accomplished by a variety of
methods. This is necessary as the speed can be used to control wall
thicknesses when sealing the tubing. The motor drove a splined shaft. The
head and tail stocks were connected to this shaft by a timing chain (slack
could be adjusted out by a snubber bar). There can be no slop (backlash) or
the seal would devitrify or even break on cooling.

The tailstock must move in order to make a seal. There was always a crank
on the tailstock to drive the movement and a gear rack under the bed. The
bed was covered by a heat protective stainless steel sheet which passed
through the bottom of the tailstock. For heat we used movable surface mix
rack burners on the lathe bed, hand torches, or a Carlisle CC mounted on a
movable stand. Fuel was high pressure natural gas, propane, and/or hydrogen
depending upon the job. Oxygen was always used.

Most of the items we made utilized borosilicate glass with a relatively low
coefficient of expansion. Sealed glass must always be annealed to remove
stresses caused by the heating. There is much more to glass working than
merely making the lathe. Larger tubing requires a glass saw for cutting. A
wet belt grinder comes in handy. HF is often used to clean fresh cut tubing
ends before sealing. Various graphite paddles and tapers will be needed.
Heat resistant gloves are a plus!

A large part of glass lathe expense is the various chucks for holding the
tubing. Some were even 6 jaw (2 separately operating 3 jaw chucks in one
chuck) for holding a tubing in position within another piece of tubing. We
used to shim everything with (dare I say it?) asbestos tape. The through
hole was at least 4" on most of the lathes I used.

A good glass lathe is not cheap and would have very limited use without all
of the required associated equipment.
Jim

--
James P. Riser
Http://www.JamesRiser.com

In article et, JAMES RISER
says...

Most of the items we made utilized borosilicate glass with a relatively low
coefficient of expansion. Sealed glass must always be annealed to remove
stresses caused by the heating. ...

The best part is seeing one of those large 'strain-O-scopes'
which are crossed polarizers. The part is placed between the
two sheets, and any areas with strain still in them light up
in all kinds of patterns.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

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.

A glassblowers' swivel is used - usually with plurostoppers (nesting multi
sized rubber stoppers).
Jim

--
James P. Riser
Http://www.JamesRiser.com
"Allan Adler" wrote in message
...

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.