elementcollector1
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Cutting a Test Tube / Glass Tubing
This isn't a chemistry-related project, but I thought I might bring it up.
What would be the best way to go about cutting the ends off of a test tube so that it's a fairly long, even tube? Would this be mechanical, or would
dissolving in molten NaOH also work?
If a test tube fails, I might just order some glass tubing. If I do, how could I cut that (assuming it's a significantly longer tube than what I
need)?
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Lambda-Eyde
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http://www.ilpi.com/glassblowing/tutorial_cutting.html
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elementcollector1
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The problem with this is I usually want to cut the ends of a test tube off, so I can't exactly grab on to the end and snap. This will be useful if I
end up ordering or buying glass tubing, though.
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Lambda-Eyde
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Sounds like method #3, #4 or #5 will do the trick, then. A Dremel with a diamond cut-off wheel could do the job.
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watson.fawkes
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For taking off an end like that, you can make a circumferential scratch with a file or glass cutting wheel. You'll need a jig to hold everything in
place, but it's just a V-block to hold the test tube and a holder for the cutter. After you have the scratch, heat up the tube in a flame. The end
will pop right off.
Standard lengths in glass tubing are 4 feet and 1.5 m.
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Endimion17
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Huh, this can be a tough one. Try scoring it like watson.fawkes said, but wet the scored mark with water before applying flame directly up at the
bottom. Water greatly increases the stress and is usually used when wider tubes are being cut.
If that fails, take a piece of resistive wire. Make a setup that will cause it to glow orange rather quickly.
Make a loop where you want to do the cutting (watch out not to create a short circuit), tighten it and then apply the current. It usually works. If it
fails, score it, wet it, then tighten it in the resistive loop at the score mark.
This method works for cutting regular bottles.
If the cut is not even, you can carefully correct it with a sand paper, but then you must polish it with an oxidized flame and anneal in safety flame
until you cover it with soot.
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Sedit
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Shock it.
Fill it with water to where you want to have it cut, freeze the water and drop it into boiling water. You should get a nice clean break right where
the water level was.
You could also do the same with boiling water in the test tube and place it into ice water as well but I can't remember if I have ever cut
borosilicate this way or not so GL.
This method provides a very clean cut BTW.
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elementcollector1
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Quote: Originally posted by Sedit  | Shock it.
Fill it with water to where you want to have it cut, freeze the water and drop it into boiling water. You should get a nice clean break right where
the water level was.
You could also do the same with boiling water in the test tube and place it into ice water as well but I can't remember if I have ever cut
borosilicate this way or not so GL.
This method provides a very clean cut BTW. |
That's an... interesting method! What does the broken-off part do, just sink to the bottom?
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Sedit
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Yeh just fractures at the point where the air and water meet. Its a glass cutting technique an artist friend of mine taught me and I have used it a
few times.
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
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sparkgap
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| Quote: Originally posted by Sedit |
Fill it with water to where you want to have it cut, freeze the water and drop it into boiling water. You should get a nice clean break right where
the water level was. |
Since water expands on freezing, I suppose one should make some allowances if a cut at a precise location is needed...
sparky (~_~)
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Endimion17
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| Quote: Originally posted by Sedit | Shock it.
Fill it with water to where you want to have it cut, freeze the water and drop it into boiling water. You should get a nice clean break right where
the water level was.
You could also do the same with boiling water in the test tube and place it into ice water as well but I can't remember if I have ever cut
borosilicate this way or not so GL.
This method provides a very clean cut BTW. |
Huh, that means your test tubes are quite crappy, probably cheap sodium glass.
Borosilicate test tubes have to endure such shock without snapping.
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Sedit
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I have however done similar with Boro by making a circle score all the way around the tube, hitting it with a torch a the bottom and dipping that in
water.
Just play with it you will see.
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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