Instructables

Where to buy large glass tubes?

I need several glass tubes (10-20) that are around 30-40mm in diameter and 6 feet long. They also can't be rediculously expensive, I've been searching for a while, but all I've been able to find is glass with a length of 4 feet and a diameter of like 10mm. Any help?

Gjdj35 years ago
The real question is, what for?
Gjdj3 Gjdj35 years ago
Scratch that, I found the comment explaining it.
Sandisk1duo5 years ago
you can get a 1inch diameter tube if you empty out florescent lights
This jogged an old memory. Mother's Energy Efficiency Book, 1983, Mother Earth News, has an article about using discarded fluorescent tubes as collector pipes.

The article describes making a "tube cutting tool," wrapping a short length of .034 in. stainless steel wire around the tubes, then energizing with a 12V car battery. When the glass cools, it does so unevenly and breaks cleanly at the heated line...
it would be best to first score the glass, then get the wire cutting tool
I dunno, never tried it. The author probably cut hundreds of tubes to arrive at the technique (his collector panels used 29 tubes each.) Scoring doesn't seem necessary; the wire melts into the surface. Other techniques would work, for sure. He also recommends filling the tubes with sandblasting sand and tip repeatedly to remove the inner coating...
guyfrom7up (author)  gmoon5 years ago
what should I do about the mercury? I need 16 tubes, and one isn't that big of a deal, but 16 seems to be a little dangerous. I don't want any drain bramage xD
just make sure you empty them out carefully, maybe wear a mask
The glass is very thin, it is very likely to be unsuitable for the high-vac work guyfrom7up wants to do.

L
he was going to make "giant nixie bargraph displays"

i'm pretty sure that nixie tubes have some gas inside

however , i could be wrong
guyfrom7up (author)  Sandisk1duo5 years ago
well, yeah, but in the process of making them pressures get down to below 1x10-2 torr, and whenever filled with gas they are around 5-12 torr. The glass does seem really thin for doing something like this, but they have to do this in the process of making them, so I don't know...
I'm not convinced that regular fluorescent tubes are pumped down as far as 10-2 torr.
On another note - do you have any experience blowing glass?

L
guyfrom7up (author)  lemonie5 years ago
i have expierience not blowing glass, if that was another question xD I can't roll by own tubes, if that's the second.
It was the techniques required to seal the tubes I meant, it's a bit tricky. You might be wise to play with cheap glass a bit before buying anything.

L
guyfrom7up (author)  lemonie5 years ago
right, that was the plan. I'm going to try and learn how to using little glass test tubes (for testing xD). And the electrodes don't look to hard to make, after all, I saw a youtube video on it, so I'm pretty much a proffesional xD. do you know if the electrode materials used are important?
For long term use I think the electrode materials may be important, but you'll probably know at least as much as I do on this. L
What does a torr specify?
Yikes. Yeah, it's not 1983 (date the book was published) anymore...

If you do it, do so outdoors. And be very, very careful.
guyfrom7up (author) 5 years ago
Well, my plan is to make giant nixie bargraph displays, and I thought about emptying out flourescent lights, but I think it adds a bit more of unnecessary danger to the project. And yes, it must be glass because of outgassing.
there's no danger if you take the right precautions
Hmm. Our local stained glass supplier has borosilicate tubes, but they're not 6 feet. Try a scientific glassware supplier, or a labware department of a local university. Like guyfrom7up asked, what is your application? Can you scavenge from fluorescent tubes? Does it have to be glass, or could you use clear polyester tubes from a plastic supplier? That would be much safer imho, if it suits your app.
Needless to say, exploding glass can not only be a hazard to you, but also to anyone admiring your invention, not to mention opening fluorescent tubes exposes mercury to you and the enviornment, and should never be attempted by anyone...
You know, that's a question I'd like an answer for aswell, there's a few things I'd like to build...
guyfrom7up (author)  killerjackalope5 years ago
what are you going to build?