Picture of Easiest way to cleanly cut bottles
I know there are already quite a few great bottle cutting instructables but I find this technique to be the fastest, and in my expirience the cleanest and easiest way to cut bottles. My project was to make a set of drinking glasses from old pepsi bottles that I had lying around, but you can use this technique for whatever project you like.
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Step 1: Tools

Picture of tools
All you really need for this is a simple glass cutter you pick up from a hardware store and a propane torch with a relatively fine tip. It may work with something else like a lighter, candle, larger torch etc. but I have yet to try those as my little benzomatic pencil torch has worked so well. My preferred way to do this also involves a lathe with a very slow speed but it can be avoided as I show later in the instructable. All you really need is some way to rotate a bottle at a relatively slow controlled speed, Ive done this on a potters wheel also but you could easily rig something up with a geared motor from a toy car, its only needs low torque.

Step 2: Nick

Picture of Nick
This is what makes this method so much easier, you dont need some jig to cut around the edge of a bottle perfectly all you need is a to make a little (like 1/8") nick with the glass cutter that would follow around the circumference of the bottle. It should be a decent nick with quite a bit of pressure applied to the cutter.
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Rather than sanding the cut edges, could you try putting the bottle back in the lathe and using a larger blowtorch to heat the edges so they melt and round themselves over?

Also, could you use a carbide tool in the lathe to get the nice even score line?
no if you heat glass unevenly it will shatter, so just heating the edge enough to melt the glass will break the bottle.
Yeah... That is dangerous and no good.
gfwhell2 years ago
I once read, cutting bottles can be acheived with a piece of string tied around the line to be cut., the string is then soaked in "fuel" and ignited. pulling the bottle down into cold water untill the level is the same as the string.
This induces the bottle to shear at that point espeially if it has a scratched line in the glass.

Worth a try?

String method works well,used it several times.You can actually fill the bottle to the break line with water and light the string also
Another neat way is fill the bottle with cold water,wrap it with nichrome wire one time(don't let the wrap touch,just close)and hook it up to a 6v lantern battery(or similar).Makes a neat little "pop",and splash,so don't do it inside,unless it's in a bowl,pan,etc.
GLFaria2 years ago
As has been correctly pointed out, glass is an amorphous solid, not a liquid.
A pane of glass placed vertically will not become thicker at the bottom no matter how long you wait for that to happen.
Glass tempering is essentially a physical process, where the "tempered" properties are achieved by inducing compressive stresses on the surface (in return for tensile stresses in the core). You nick the surfece, the stress equilibrium is cancelled, the glass shatters.

By contrast, metal tempering is essentially a chemical process, where the crystalline structure of the material is modified to get the desired properties. It is not stresses you are looking for here - in fact, they are generally undesirable - it is a different chemical and cristalline structure.

Maybe needless to say, I have worked in both fields...
coppeis2 years ago
Where did you get the Pepsi in a glass?
srsantafe2 years ago
Thanks for this method, I´ll try to make it soon,nice idea to do it
Happy2Think2 years ago
Not everybody has a Sherline Lathe, so it is easy with a Jig
Spinning it on a string seems to work as well:
slmayhugh2 years ago
After heating...apply ice. Don't make the glass too hot or it will shatter. The Ice works really well. I was using that method back during the very first Earthday!
maniacse2 years ago
Nice idea! Thanks for that...
valveman2 years ago
Nice instructable. I suppose a variable speed drill could also work instead of a lathe.
ASCAS2 years ago
Great Idea !! I'm going to sell recycled glass cups from now on :)))
It is a fluid amorphous solid. I use a regular propane torch, and a potters wheel to do mine. Then a belt sander with 150 grit sandpaper. Works like a charm. If you want it a little smoother, you can use 320 grit wet dry with a touch of veg oil.
uziXwraith2 years ago
could you use a bottle torch from autozone?
whad do you use for the light sanding? emery cloth(think this is the correct spelling)?
Very nice method! I have not cut glass before, but might have to give it a go using a few Ski bottles.
rimar20002 years ago
Awesome, thanks for sharing.
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