Cutting a glass bottle

I’m wanting to cut the bottom off a glass bottle to make a candle holder. Initially I thought I could do this by cutting very slowly with a water-cooled abrasive cut-off wheel. Turns out I can’t.

Baden-Powell’s Scouting for Boys indicates that you can cut bottles by filling them with water to the desired level and placing them in the ashes of a bonfire, whereupon they crack at the waterline as a result of thermal stresses. Not having a bonfire handy, I tried filling the bottle with cold water and immersing it in boiling water. Didn’t work. I tried again, chilling the water and the bottle in the refrigerator. Didn’t work. Tried a third time, this time placing the bottle of chilled water in a pre-heated oven. Bottle sat there uncracked, water inside boiling happily, mocking me.

An appendix of a US Army manual states that you can cut the neck off a bottle as follows. Wrap a fuel-soaked string around it, ignite the string, and holding the bottle horizontal, rotate it to create a ring of hot glass. Then plunge the bottle in cold water and knock off the neck on a hard object. Before I start playing with burning string and buckets of water, does anyone know an easier way to do this?

There are special tools for cutting glass. The scoring devices used for glass plates aren’t much good, but for drilling holes you can use bits masde for ceramics (I think they have diamond bits in them), and for cutting straigt across there are diamond saws. That’s what we’ve used in the past, and it works pretty well. Not as quick or as flashy as the methods you suggest, but they do work.
Make sure you’ve got the bottle held down securely and are using a mounted saw or drill.

You can get a blade for a standard hacksaw that consists of a wire coated with granules of tungsten carbide; I’ve cut bottles with these before - works best on thick-walled ones - if they’re polygonal in section, even better, because you can use the blade to cut a ‘trough’ in each face before cutting all the way through. You have to take steps to dampen any vibration and movement (i.e. clamp down the bottle, padding the table and clamp with heavy rags), you have to take care not to let the saw blade yaw and it helps if you lubricate the cut with a little WD40 or something, just so it doesn’t stick and shatter.

Oh, and definitely wear good eye protection and a good dust mask.

I’ve heard a wrinkle on the method you describe – you fill the bottle with cold water to the desired level, tie a string around the bottle at the water line, soak it in something combustible (wood alcohol, maybe), and set the string on fire.

Don’t know if it works, but I’ve always wanted to try it.

Bottle cutting Kit

If you don’t want to pay that much for a kit, back in hippie days…
Uou can use an ordinary glass scorer. (A few bucks at any hardware store.) Improvise a way to hold it firmly upright (Got a vise?) and rotate the bottle against it, ONCE, pressing firmly. The guy I knew who was really into this built a sort of rig: two boards forming an ‘L’ shaped trough and the cutter projecting through a whole in one of the boards, and a moveable block of wood he could set to keep the distance from bottom of bottle to cut line steady at whatever desired height.

Anyway, once the bottle is scored, you need a ‘tapper’, something long enough to reach down into the bottle to the score line, thin enough to go through the neck (duh) with a bit of weightiness at the end. His was made from a chunk of wire coat hanger (not the flimsy white ones that dry cleaners put shirts on, the stiff kind) cut and straightened out, with a lead ‘sinker’ secured firmly onto the end.

You stick the weighted end of the tapper inside the bottle and start tapping - gently, mind you – along the scored line on the inside of the bottle. Tap tap tap. Gentle little taps, turning the bottle slightly each time. Generally the bottle split apart very neatly sometime during the 2nd to 3rd pass around.

Then you need really fine sandpaper.

BTW, heavier glass, like wine bottles, were easier to do neatly than thin glass such as pickles come in.

You can stand a bottle on a hotplate, then, using a glove or something, dunk it into cold water - the glass should crack horizontally at the water level. I’ve seen it done, but when I’ve tried it I must confess it just broke all jaggedly… :frowning:

I’ve had modest luck with the approach of scoring the bottle at the desired cut point, heating it with a torch and then plunging it in water. It wasn’t a particularly clean break, though.

One possibility is using a tile saw. If it cuts through granite, it should work for glass as well. Only problem would be making a jig to keep the bottle from spinning dangerously.

The cut-off wheel I tried was much the same sort of thing. It cut the glass okay, the problem was the localised heating from the abrasive wheel which made the thing crack. First time I was really careful, second time I was unbelievably careful, but I still cracked it.

I thing I’ll try a combination of all the cheap options -score a line with a regular glass cutter, then heat the line and dunk to pop the crack open. (The commercial glass cutter kit suggests popping the score line by heating with a candle and chilling with an ice cube.) I’ll smooth the edges off with 1200 grit SiC paper. Incidentally, it’s a Tabasco Sauce bottle I’m wanting to cut.

Probably not the same thing, then. A tile saw uses a diamond blade with water cooling. I admit, though, that I haven’t tried my tile saw on glass.

I would be inclined to find a tool or kit (like the kind picunurse linked to).

My wifebunnie and I were married at a winery; we conscripted her sister and her sister’s husband to cut the bottoms off a few dozen glass bottles to make the centerpieces for the reception. They used a kit specifically designed for cutting glass bottles and despite their reputation for coming late or not at all, they had produced a truly astounding number of centerpiece bottles by the time the wedding was to take place.

While it may not be evident from this picture, the bottles’ bottoms had been cut off, they had been raised up by the addition of washers, and (at the moment the picture was taken) each contained an unlight tea light.

Now back when I was in Elementary school we had a err fair or festival day. There was a guy who would cut the glass soda bottles for the kids.

From what I remember from such a time ago. He had a red hot wire he used to “cut” it. How he made it I do not know. It was a facinating thing.

Back in the late 60s or early 70s we bought Dad a bottle cutter kit.
It consisted IIRC of a flammable liquid some string and some fine sandpaper.I think he plunged the empty bottle into ice water after burning the string which was tied around the bottle at the strategic separation point…
He used liquor bottles for his projects and cut quite a few bottles but he probably had more fun emptying the bottles.:slight_smile:
Bottles nowadays have plastic in them so they don’t cut as easily as in the old days.
We tried a glass cutter back then but didn’t have any luck so we purchased the glass cutter kit.
Dad had a lot of fun with those projects.