flame

Thanks for all the helpful suggestions.
--
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.

"glassman" wrote in message
...

"Moonraker" wrote in message
.. .

"glassman" wrote in message
...


and you thought I was testy?


Nah. I just have a low tolerance for ignorance.



Geez then what do you think of stupidity?

You mean Brady and his ilk?

No, Moonraker needs his tubes and fingers tied to prevent procreation and
rudeness. You can block his messages just like e-mail on your brower if you
wish.
The real problems with using an arc for working glass are the very high
temperature in a very small space and the interesting problem that most
glass becomes conductive when melted. (And yes people have thought of using
a carbon arc to melt a pool of glass, but you need a safety cutoff when you
dip the pipe in the glass and because you need to melt the glass with
something else like gas, what is the point of two electrical systems.)
It is possible to work glass with an electric glory hole built like the
bottle melting rig I built
http://users.ticnet.com/mikefirth/bottle.htm#NECKMELT but it doesn't scale
up very well, I am told. People melt glass with electricity all the time,
but it is done with silicon carbide elements in a highly insulated box that
is opened only briefly to get the melted glass out. The actual working of
the glass is done with a gas glory hole.

--
Mike Firth
Furnace Glassblowing Website
http://users.ticnet.com/mikefirth/
"Allan Adler" wrote in message
...
Steve Ackman writes:

In , on 05 Sep 2006 11:05:50 -0400,
Allan Adler wrote:
Is there any kind of glassblowing one can do without using flame?

I've never tried this for glass, so in that context
it's completely theoretical:
Back decades ago when I had an AC buzzbox (arc
welder), I had an accessory known as a carbon arc
torch; basically a hand-held fixture for holding a
copper-covered carbon electrode a fixed distance from
a ground electrode. Pull the handle (squeeze the
trigger) to bring the two together and strike the arc,
then release to create a 3/8" or so gap. You now have
a blue hot arc in front of you.
The amount of heat could be controlled by adjusting
the amperage on the welder. Also, there were 1/4" and
3/8" (and larger?) carbons you could use. The size of
the gap also controlled, to some extent, how focused
the arc would be.

Thanks very much for your comments. One advantage I can see for flame
is that you can easily move it around on the glass to keep one part from
expanding faster than other parts and maybe breaking the glass. That
doesn't
seem to be a feature of the carbon arc apparatus you describe. I was
thinking
in terms of some well insulated container with lots of little heating
elements
all around the glass, elements which can be controlled independently, so
that the glass heats up as a whole in a controlled way but the particular
part you want to soften gets more heat. I have no idea whether something
like that could work or whether it is actually used. If the insulation is
good enough, the amount of heat produced by the heating elements might
not
need to be that great, since the heat insulation would cause the heat to
accumulate. It just might take a long time to get to the right temperature
and a long time to cool.

Is Moonraker the local judgemental heckler for rec.crafts.glass or is he
right about this question being off topic for this group? If so, I
apologize,
since it wasn't intentional on my part.
--
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.

"Mike Firth" wrote in message
m...
No, Moonraker needs his tubes and fingers tied to prevent procreation
and
rudeness. You can block his messages just like e-mail on your brower if
you
wish.

Go **** yourself.

Unless of course you have an electric glory hole such as one of these
http://www.electroglass.com/gloryholespec.html

Mike Firth wrote:

No, Moonraker needs his tubes and fingers tied to prevent procreation and
rudeness. You can block his messages just like e-mail on your brower if you
wish.
The real problems with using an arc for working glass are the very high
temperature in a very small space and the interesting problem that most
glass becomes conductive when melted. (And yes people have thought of using
a carbon arc to melt a pool of glass, but you need a safety cutoff when you
dip the pipe in the glass and because you need to melt the glass with
something else like gas, what is the point of two electrical systems.)
It is possible to work glass with an electric glory hole built like the
bottle melting rig I built
http://users.ticnet.com/mikefirth/bottle.htm#NECKMELT but it doesn't scale
up very well, I am told. People melt glass with electricity all the time,
but it is done with silicon carbide elements in a highly insulated box that
is opened only briefly to get the melted glass out. The actual working of
the glass is done with a gas glory hole.

"David Billington" wrote in message
..
..
Unless of course you have an electric glory hole such as one of these


I once knew a girl..... oh forget it.


--
JK Sinrod
www.SinrodStudios.com
www.MyConeyIslandMemories.com

"glassman" wrote in message
...

"David Billington" wrote in message
..
.
Unless of course you have an electric glory hole such as one of these


I once knew a girl..... oh forget it.

That's "shocking".

But look at the specs for those things and you will see why they are not
used very much.
$9,996 for a 12" opening glory hole which is not large using 21.6 KW power
at 240 volts which is 90 amps, which requires a really, really serious
wiring job or go to 3 phase, which is also a serious wiring job, not
something you plug in. Silicon carbide heater bars are brittle, so don't
tap them with the glass. Building one would be tricky as it requires
special transformers and controllers (see CraftWeb Glass Forum for lengthy
discussion of Electric Furnaces using SiC bars and other methods.)
In comparison, building a gas gloryhole about the same size is relatively
uncomplicated and costs about $700 with simple controls, $2000 with a more
extensive safety gas train (often not used on glory holes because they are
usually attended when on.)
Their operating figure of $65 a month at 7 cents a KWH calculates out to
43 hours a month (43 hours x $0.07 /kwh x 21.6 kw = $65.016) which is about
a fourth of what would be expected in even a modest shop since it is just
over 10 hours a week. Even with the fast heat up given (15 minutes), you
would be using up 1.25 to 1.5 hours a week if it is just turned on once a
day (no shut down for lunch or no lunch.)
And it doesn't help that here in Texas, my last electric bill was based on
$0.148/kwh.without all those funny little charges added in.

--
Mike Firth
Furnace Glassblowing Website
http://users.ticnet.com/mikefirth/
"David Billington" wrote in message
...
Unless of course you have an electric glory hole such as one of these
http://www.electroglass.com/gloryholespec.html

Of course, what is missing (he realized after sending the long message) is
the duty cycle of the glory hole. If the hole somehow manages to stay hot
and have the elements on only 25% of the time, which seems low, you get up
to 40 hours a week.

--
Mike Firth
Furnace Glassblowing Website
http://users.ticnet.com/mikefirth/
"Mike Firth" wrote in message
et...
But look at the specs for those things and you will see why they are not
used very much.
[snip]
over 10 hours a week. Even with the fast heat up given (15 minutes), you
would be using up 1.25 to 1.5 hours a week if it is just turned on once a
day (no shut down for lunch or no lunch.)
And it doesn't help that here in Texas, my last electric bill was based
on $0.148/kwh.without all those funny little charges added in.

--

In , on Tue, 5 Sep 2006 11:34:28
-0400, Steve Ackman wrote:
In , on 05 Sep 2006 11:05:50 -0400,
Allan Adler wrote:

Is there any kind of glassblowing one can do without using flame?

I've never tried this for glass, so in that context
it's completely theoretical:

Back decades ago when I had an AC buzzbox (arc
welder), I had an accessory known as a carbon arc
torch; basically a hand-held fixture for holding a
copper-covered carbon electrode a fixed distance from
a ground electrode. Pull the handle (squeeze the
trigger) to bring the two together and strike the arc,
then release to create a 3/8" or so gap. You now have
a blue hot arc in front of you.

The amount of heat could be controlled by adjusting
the amperage on the welder. Also, there were 1/4" and
3/8" (and larger?) carbons you could use. The size of
the gap also controlled, to some extent, how focused
the arc would be.

I may actually still have this piece of hardware
hidden away in a box somewhere, and if I run across it,
I'll see how well it works on my current DC ARC / TIG /
Plasma unit.

I ran across it today. Main problem is that it really
is designed for AC, and the arc tends to walk around
the gap more with DC. IOW, even if the carbons are
stationary, the "flame" isn't. I surmise it may due
to the copper migrating too much with DC.

That said, I did manage to melt some glass with it.
1/4" electrodes; machine set at 30 amps. In order to
get a stable arc, I had to go with something less than
1/4" gap. It was really too much of a pinpoint heat
source at that setting, so the glass bubbled/boiled.
All other considerations aside, you'd need more current
across a wider gap to get a "softer" arc with more heat
so you could work the glass farther out.

What amazed me was that the rod (standard COE 104)
didn't crackle and spit as it tends to do when you heat
it too aggressively.
Since I don't have an AC welder any more, that's as
far as I took the experiment.

From what I saw today, I'd have to say that with the
right setup and a little while dialing in, it certainly
would be possible to do some beadmaking and light
glassblowing with a carbon arc.

I would hastily add that I wouldn't personally go
to the bother of figuring it all out since oxy-propane
is a tried and true method, and I already have that
setup... albeit not set up at the moment.