Couple of interesting bottle cutting methods

[steamingbill]

Was googling how to cut very thin glass cylinders - after destroying my first one.

Found these and thought they were interesting

this method with hot and cold water https://www.youtube.com/watch?v=sFXngPx3w3M

this method with a soldering irons https://www.youtube.com/watch?v=vZEE3tyDdoo

and this one is crazy but it seems to work quite well - could be useful if you want curved wavy cuts

https://www.youtube.com/watch?v=BG-BT6Jspko

Any other methods I could investigate - wanting to cut cylinders for stirling engines and have got some knicks knacks from the op shop but they are made of fairly thin glass and I messed up the first one terribly.

Have got a 10" diameter thin glass vase destined to be an LTD engine and want to be very confident when I do it.

Bill

[Evanism]

easiest way is to put a string around the bottle, put metho on it, light it and let it burn for 5 seconds then dunk it in cold water. Flick it with your finger and the top magically pops off at the sting line.

[AlexS]

easiest way is to put a string around the bottle, put metho on it, light it and let it burn for 5 seconds then dunk it in cold water. Flick it with your finger and the top magically pops off at the sting line.
That's the method used by diggers in WW II to make 'Lady Blameys' - drinking mugs made from MT beer bottles. A handle was made from twisted wire.

[steamingbill]

Here is an elegant solution

https://www.youtube.com/watch?v=xfYj-sq78DU

and it seems that a frequent mistake that many people make is too much temperature differential when using the various thermal shock methods. That is probably where I've been going wrong, nasty jagged edges and secondary cracking rather than clean lines

This bloke explains it very well and gives a good demo

https://www.youtube.com/watch?v=wwwKD1VAQCo

Tried the soldering iron idea - worked fairly well but still looking for the best way to do the 10" cylinder on thin glass. Not confident with burning string method.

Have just got new internet connection and now have fast unfettered access to utube - quite amazing to finally have a good look around without worrying about cost and usage limits.

[rrich]

easiest way is to put a string around the bottle, put metho on it, light it and let it burn for 5 seconds then dunk it in cold water. Flick it with your finger and the top magically pops off at the sting line.

This works very well. If a precise and square cut is needed, make a jig and scratch the bottle at the desired point. Then the string and flammable liquid method works even better.

As for the jig....

Make a box but with only three sides. Take a cheap carbide tip scribe and place it in the desired position from the bottom and through the side of the box. Rotate your bottle against the bottom of the box and the scribe point. The string, flammable liquid and fire will give a really nice clean cut.

[Bob38S]

Making the cut is the first step.

Cleaning up the sharp edge shouldn't be ignored, a small, fine sharpening stone and plenty of water to polish the edge smooth is highly desirable and makes it much safer.

[steamingbill]

Thanks for the various tips.

I tried the string and metho - didnt work very well for me - put the string on the scratch then lit it, dunked in water and end result was a bit jagged.

Am having spectacular success with the soldering iron method and so will stick with that for bottles. After several messes I managed one perfect mirror smooth cut and then a few more with minor imperfections. Cylinders now ready for displacers. Worth persevering with soldering iron if it doesnt work at first.

I also tried using the tile cutting saw (wet diamond blade) - that was very quick but there were quite a few chips knocked out around the edge - marked difference to the very clean end result from the soldering iron method. Maybe a better jig to hold the bottle steadier would help with the chips.

Was wondering if those diamond blade tilesaws might be somehow adapted to sharpen metal scrapers and lathe bits ?

So .............. am now confident with bottles off to have a go with much thinner glass tomorrow.

Broke out the Aldi glass drills, for $5 they were a bargain and worked very well. And the Aldi el cheapo diamond sharpening blocks were great for smoothing the unsuccesful jagged first attempts.

Bill