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.

Step 1: 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.

Comments

[londobali]

Here are my results with your method, which later on i use a turn-table i manage to put together..
Thanks again!

I've tried with different kinds of bottles, thick, thin, big, small, even the square one..
It works well for me and I'm pretty satisfied with this method..
Check out my pictures, all done with the nick and pen-torch technique.
Notice the four similar ones are local beer bottles, very uneven thickness!
The square bottle works fine, only needs a bit more sanding.
The equil bottle is widening towards the top, although it's not a horizontal cut, it's very straight.
The super thick bottle and tiny-and-thin bottle also works great..
:)

[asegade]

Very cleaver the string turning 8)
I'll test your method.
Thanx

[londobali]

thanks for sharing Jor2daje, the video helps a lot..

There's so many different technique/method on the web, and yours is very simple and i have a pen torch and a glass cutter is very cheap around here.. :)

I'm wondering about the success ratio of your method, and if different bottles have different success.. I have some pretty exotic bottles that i want to cut for a project but i'm really afraid to screw up.. and i cant just try it out on them since i only have a couple..

Did you manage to try Jor2daje's method, asegade?
if yes, would you care to share your experience?

I'm also wondering about the nick vs the scoring all-around..
I think the nick is better, it gives a start point for the crack and then the crack will run straighter and smoother.
The all-around-scoring would be rougher. all of the tiny fractures along the score-line might give way for the crack to jump out of line and create a rough crack..

What do you guys think?
thanks again!

[tacamaral]

Just tried it with my butane pencil torch and it worked just fine. Except I still need to find a way of rotating the bottle a little more accurately... : )

[fretted]

you tube

www.Greenpowerscience.com Water cutting a bottle cleaner and you can reseal the bottles and make vacuum tubes

Pretty cool

Nice Ible

[mwyethsr]

How do you sand the rim ? what do you start with ?

[kabira]

Sanding glass with a wet sandpaper will give fairly finished edges.

[flyingpuppy]

When I made my outdoor chandelier with glass bottles, I sanded the edges with a rough, then a fine sandpaper. The bottom part of the bottle (which I didn't use for the chandelier) only needed a fine-grit sandpaper to take the sharpness off the edge so it wouldn't cut your finger.

[flyingpuppy]

But everyone has a cake pan, so you could "spin" the bottle as shown here:  cut glass bottles in 3 minutes (second video)

[Hawkeye_bkj]

Does this affect the tempering of the glass any?

[pacifcace]

The bottles can't be made of tempered glass, or else they'd burst into a million pieces with the first cut. I wouldn't expect this process to seriously alter the crystalline structure of the bottle though, there isn't enough heat being applied.

[David-Yezbak]

but glass isn't crystal, it's liqud, very dense liquid, but if you leave a window that is perfectly flat, 20 years later the glass is thicker at the bottom.

[illegitimi]

Sadly this is an urban myth. Glass displays some similarities with a liquid, but the thickening of glass in windows is sadly just down to poor workmanship :)

[David-Yezbak]

no you can go to the finest glass crafters buy thier best glass and this will still slowly move with gravity.
i suppose liquid wasn't the best word i could have chossen but i don't know the real SCIENTIFICT term for theis type of matieral. i may be 15 but i know quite abit about science.

[nwlaurie]

The thickening of glass in church windows is often cited as 'evidence' of glass being a liquid. In fact, much of the old glass was made by 'spinning', i.e. blowing a sphere, cutting it open and spinning the resulting disk to produce a large circle of glass with a cheap 'n nasty 'bullseye' in the middle (often used for windows in the poorest of homes).
This disc was inevitably thicker near the centre and once cut down into panes gave sheets of uneven thickness.
Anyone then using this glass would (probably) tend to put the thicker due at the bottom if only because it 'feels right' that way.

[Vengence]

Yep. I saw the debunking of this on some TV show. They measured all of the glass in an old church, and there were nearly as many panes that were thicker at the top as there were panes that were thicker at the bottom; showing that was just the way the panes were made.

[pacifcace]

You're right that glass doesn't have an ordered crystalline structure, but it's not a liquid it's an amorphous solid. I still stands behind my statement, though, that these bottles can't be tempered glass and this process will not cause problems. Temper in glass does not work like temper in metals.

[David-Yezbak]

anamorphus solid that was the word i looking for thank you, and i agree with you tempered glass would shatter but i was just stating that glass isn't 100% crystaline it can shift.

[Hawkeye_bkj]

Ok, I am used to working with steel, so bear with me. Wouldn't adding any heat to it affect the crystalline structure causing stress fractures?

I have seen a method that scores the bottle the whole way around, then uses hot water and cold water that does the same thing but on a smaller scale yet. The result was a bottle that after it was cut, the seam when held together would still hold water

[noexit]

Amorphous solid means that there is not crystalline structure, so no.

[sridhara]

tying up a string around bottle where it is to be split ,wetting the ctton string with kerosene and pulling apart as the bottle cools is a much easier ,faster and simpler method .Best results on your second or subsequent efforts.
u s rao

[JamesMD]

Enjoy? That's Coca Cola!

[sconner1]

Both brands ask you to "enjoy".
Dictionary words can't be trademarked.
That's why everything is spelled wrong in advertising.

[JamesMD]

Hmm. I guess it does. Never noticed that before... but then again, I don't drink Pepsi... and Coke on rare occasions.

[uuglypher]

What goes around comes around. Making glasses from wine bottles was a fad in the mid-60s. Showed my dad who laughed and told me it was a a way to save money back during the early years of the Great Depression - '29, '30. My Grandad chimed in mentioning a childhood friend's father in the 1890s who used to hand-engrave and sell glasses and small vases he cut from bottles. I wonder how far back it really goes?

[glassbreaker]

Glass - any kind of glass - has surface tension. The scoring of the surface breaks that tension. Applying heat will cause an expansion of the glass - even that scored line. That is why glass breaks on score. Fractures occurr when surface tension is not cleanly scored, which is often the result of going back over a score to "be sure".

Internal fractures can occur in any glass. Usually from being improperly cooled. There is a "Wiley Coyote" effect when there are internal fractures. The Krinkle- Krinkle effect!

If the glass does not break cleanly - stop. Look carefully - tap lightly with ball end of the scorer shown in this artical. Turn glass at different angels in light. There is a great possibility that there are fractures you may not see right away. Note the Krinkle effect mentioned above.
I Would Not TrustbA Glass Not Cleanly Broken!

Do not try to polish edges with a torch. Glass "polishes" at 1250 degrees F. There will be too great a difference in temperatures.

Have fun!
Been there, Done that, have the T-shirt and have made living cutting glass

[GLFaria]

May I refine a little? ;=)
Glass having a very low resistance to tensile stresses, it always starts to break from the surface most subject to stresses of this kind, whenever that surface has the slightest imperfection.

If you heat a bottle, or any cylindrical shape for that matter, the external surface, being larger than the internal one, expands more, so becoming subject to a greater tensile stress than the surface on the inside the bottle. If you then score the outside nsurface the bottle will break. This is mainly due to the added tension induced by heating and expanding.

One may "score" a glass bottle on the outside without breaking it - you may, for example, drill a bottle to make way to an electric wire for mounting a lamp - provided it is not subject to the extra tensions induced by heating.

(most of the time glass is not actually cut, but scored whith a small wheel, usually made of tungsten carbide. Then it is slightly bent to the side opposite the scoring and, the scored surface becoming subject to a tensile stress, the glass breaks starting from the score)

It is true all glasses have surface - and internal - stresses, unless perfectly annealed under very controlled conditions.

In the case of bottles and similarly shaped pieces, the tensions arise mostly from the shape itself, which makes for uneven cooling. But in many cases bottles can be cut without shattering.

In flat so called "annealed" glass, a very slight amount of controlled tensions is induced on purpose during the cooling process to ease breakage on cutting.

In the case of tempered glass, strong compressive stresses on the surfaces - balanced by equally strong tensile stresses in the core - are induced on purpose. Glass is highly resistant to compression, and as it always breaks from the surface subject to a tensile stress, this actually makes the piece work as, for example, a pre-stressed concrete beam. At a price - if you nick the surface of a tempered glass, the equilibrium between the compressive and tensile stresses is broken and the glass literally explodes. That is why tempered glass can not be cut in any way.

Sorry, I digress...

[nkhalsa]

When I had to cut a large test tube used in a floral display, I did not know about the heat method. I tried to score it with a glass cutter, didn't really do much. I chucked it in my lathe and tried various ways of scoring it, none of which made much of a dent. Finally, I put a diamond wheel in a dremel and held it to the slowly turning tube. That did the trick, but left an uneven cut when it finally broke away.

[Quizicat]

Are you saying that you only need a single 'nick" in the glass, Not a continuous cut al the way around the bottle? Thanks!

[Alex Mercer]

What I did years ago...............

I pour hot engine oil from the car into the bottle to the level where you wanna cut. Then let it cool down and easily hit it and a perfect one will come out. Oh, by the way, if you like pranks, go to http://www.instructables.com/id/The-Easiest-PC-Prank-anywhere-anytime-if-You-Hav/

[criggie]

Sorry - link doesn't work for me.

[Alex Mercer]

Oh, sorry, I know it, there is an error so I erased it. Here is the new link..........

http://www.instructables.com/id/Easiest-Coolest-Most-Effective-Stealthiest-Fun/

Please, try it and leave a comment...

[criggie]

That's working better, thanks for fixing it.

[Alex Mercer]

Just select it, right click, copy, new tab and paste that on the top bar and enter.

[scarabeetle101]

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?

[sturific]

no if you heat glass unevenly it will shatter, so just heating the edge enough to melt the glass will break the bottle.

[Alex Mercer]

Yeah... That is dangerous and no good.

[gfwhell]

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?

GF

[Bowtie41]

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

[Bowtie41]

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.