cutting bottles for glass tubes - best way to do a lot?

So, I've sacrificed a lot to gather many winy bottles over the years (ha!) and have long been thinking about a small building of 'cord-bottle cob' ...  

At some point, I want to cut half the wine bottles so that the neck of one is gone and I can slip the neck of the other inside it, then wrap with aluminium foil for a nice light tube about 18" long.  

I've cut my share of bottles before, but I'm wondering if anyone has an idea on how to do a bunch at once.   I've done pots of boiling water, cooking 8-10 scored bottles at once, then attempted to put them in cold water.  It sort of works.  Maybe I need to get them hotter?  maybe I should bake them in the earth oven??  

If it snowed around here, I'd do it in the winter, but it never really gets that cold here.

thoughts?

Following, because I am cutting bottles for a project here, and your description of the scored-bottles-in-water as "sort of" is my experience as well. I tried the burning-string method and it worked a bit better, but the breaks were irregular enough that I'm not sure I'll be able to use the bottles.

You can buy (or build) glass bottle cutters, see the links below for examples.

A few years ago I built something along this, with a standard glass cutter (the one with the wheel, last link). You find them often in second-hand garage sales, and they work forever. They are also really useful to fix a window by the way.

As soon as the bottle is marked, heat it up on a candle, and put on cold water till the line.

bottle cutter
https://www.walmart.com/c/kp/glass-bottle-cutters
https://www.aliexpress.com/wholesale?ltype=wholesale&d=y&CatId=0&SearchText=glass+bottle+cutter&trafficChannel=main&SortType=default&page=1

Standard glass cutter
https://www.aliexpress.com/item/32969006230.html?spm=a2g0o.productlist.0.0.24816ba1MVXeYI&algo_pvid=affc0b91-3d85-455f-b940-3a8b2a190346&algo_expid=affc0b91-3d85-455f-b940-3a8b2a190346-7&btsid=fdaaee17-a7b7-456e-9aeb-35d4c6726815&ws_ab_test=searchweb0_0,searchweb201602_9,searchweb201603_52

A tile cutting wet saw is often cited as the fastest way of cutting bottles.
Its the method I intend to try when I get around to it.

As to the cob wall itself, if you build the roof of the structure to be supported by posts, you can work on the cob wall infill , at your leisure.,out of the weather

The cutting part is not my problem. I have built jigs for glass cutters before, and I have a tile saw. It’s the heating and cooling on a mass scale that I would like to figure out. A candle and an ice cube seems a little slow.

One bucket of hot water, on a fire.
One bucket of cold water.

Dip the bottle in the hot water, then dip in in the cold one. Cling.

Edit: I think the secret is to dip it in cold water only till the line.

Tys Sniffen wrote:The cutting part is not my problem. I have built jigs for glass cutters before, and I have a tile saw. It’s the heating and cooling on a mass scale that I would like to figure out. A candle and an ice cube seems a little slow.

I believe the tile saw being suggested is an electric "wet saw" type, which does not require any heating or cooling.  Here's a video to remove ambiguity:



I saw a DIY show guy do it on television in decent quantity at fairly high speed.  I think he was probably using a heavy duty model, not the ones that cost less than $100.  Maybe something like this or even this, although I have no idea of the actual brand or model.  All I know is that the guy was zipping through the bottles.

Wet tile saw is the fastest and easiest in my experience! Much better success-rate than scoring (though if you don't need neat lines it will probably matter less).

My much better half is a glassblower who does a serious amount of coldworking. She would tell you to use a wet tile saw, probably with a diamond blade. Plus, the wet saw will obviate the need for respiratory protection from silica dust (though if there's any doubt, don't mess around and get yourselves some proper 3M masks).

The reason the scoring and heat-stressing work is because of the thermal differential, so yeah, if you only dip the warmed, scored bottle into the cold water to the score, or just before, you stand the best chance of replicable success. I wouldn't dip past the score line, though. And do it in a situation where there aren't any random draughts. If the bottle is warmer on one side than the other, it can affect how it breaks.

-CK