Glass cutting

I am restoring a very old miners oil lamp and I need to cut a glass bottle to make the shield that protects the flame and stops it from igniting any gasses down the pit . How do I cut a bottle ?, I seem to remember reading that you can wrap a piece of string that has been soaked in some flammable liquid and set fire to it and this will do the job, any tips .

Thanks , Ken.

I seem to remember as a child reading that you wrap string around and then twist it thereby creating heat and friction and it will split. As a young boy I tried it but didn't have the continuous strength to be successful. Trying to make a lamp shade or light. Best wishes.

I seem to remember as a child reading that you wrap string around and then twist it thereby creating heat and friction and it will split. As a young boy I tried it but didn't have the continuous strength to be successful. Trying to make a lamp shade or light. Best wishes.

Decades ago a bottle-cutting gadget was marketed. It was simply constructed from strips of flat stock. One end had a lump that was able to rotate in/on the bottle's neck, the other held a glazier's wheel. The bottle was scored, then the score line tapped until the thing broke into - hopefully - two pieces. Presumably any other means of guiding a wheel would be as effective.

I think I read about another technique in which the bottle was filled with oil (of some sort) to the level required, then a red-hot poker was plunged into the oil. The bottle was supposed to fracture at the oil-level. Sounds like Health & Safety might not approve...

No experience of either. Good luck.

Demonstration of the technique here.

.

Looks like they do it lying-down now: **LINK**

https://www.amazon.co.uk/SODIAL-Adjustable-Strength-Hardness-Cutters/dp/B07F66LMYV/ref=asc_df_B07F66LMYV

Should be easy to make something inspired by that.

MichaelG.

I would try using the type of tile cutter that uses a diamond cutting disk that is kept wet in a tray of water. It will be quite slow but I think it would be more reliable than the scoring methods.

Les.

Hi Ken,

I'm not sure using a cut down bottle is such a good idea. Bottles are usually made from soda lime glass which doesn't handle thermal shock well. The glass will get hot from the lamp flame and if a bit of water gets onto it it will likely shatter.

You would be better off getting in touch with a scientific glassblower who should be able to supply you with a length of borosilicate (pyrex) glass of the right diameter and with the ends flame polished to take away the sharp corners.

Mind you, I thought miners lamps had copper or brass gauze around them to prevent methane in the mine atmosphere from igniting.

Rehards,

Alan C.

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I would just like to thank all of you for your very prompt replies to my request for bottle cutting, I was pleased to see that I had not imagined the string cutting technique

Thanks, Ken..

Very true, but Ken is restoring an old lamp and I doubt he intends risking his life with it by digging coal from a gassy mine!

Davy's original lamp - the first practical design - relied only on metal gauze. It was dim and could cause an explosion if a draught of air pushed the flame into the gauze or if the lamp was knocked over. George Stephenson's second attempt at a safety lamp seems to be the first to add a glass shield and being brighter and relatively safe was widely used in Britain. My book doesn't say what sort of glass was used but in the early 19th Century I bet George didn't have borosilicate!

The Geordie Lamp was still imperfect and development carried on in the UK and abroad for another 50 years. A later lamp by Upton and Roberts offers more protection than the Geordie: the design calls for a 'thick glass cylinder'. The glass cylinder on Dumesnil's Lamp was 'carefully annealed' and protected by curved iron bars. Quite a few lamps were made with mica rather than glass.

The urge to smoke tobacco is so strong chaps risked killing themselves and all their mates by lighting up underground - even in modern times cigarettes have been found at the ignition point. Once reasonably bright and safe lamps were available, later improvements concentrated on ways of stopping miners from opening the lamp whilst it was lit. This may be a way of dating the lamp because later lamps have locks, say after about 1860.

For an ornamental restoration, I'd have thought ordinary glass would be fine, and doubly satisfying it can be made at home.

Dave

You can form a ring with some thick wire into 3/4 of a circle a bit larger than the jar.

Heat wire to red then touch the jar with it where you want the cut.

The crack will form under the wire so get the ring square.

If you have one, I would go for the diamond wheel tile cutter, to cut the bottle. On this relatively new miners lamp the wall thickness of the glass is just under 5mm.

Being a Miner's lamp, the 4.8 mm was probably 3/16 inch!

I have heard of the fill with very hot water and then plunge into cold, technique, to get a level split.

Since the ends will not be exposed, polishing will probably not be needed.

Howard

Protector Lamp Company are still in business, and still sell spares for safety lamps. I dealt with them many moons ago getting them to make gauze components for a nuclear job, talk about alpha to omega

Edited By duncan webster on 28/08/2019 17:26:15