Water level sight glass

Does anybody have a tip for cutting / breaking the glass tube to length.

I seem to recall that there is a knack to it but A-level chemistry was a very long time ago and I expect that tube was weaker anyway.

Thanks in anticipation


Reply to
Classic Sales
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Just file a nick in it, then snap. I use a triangular diamond needle file, but an ordinary one will do as well. If it doesn't break square or cleanly, you can trim up the end by touching it against a green wheel. (Carefully!)


Reply to
Phil Ashman

If you want to smooth the cut end, heat it slowly to nearly red hot in a flame. The glass will soften slightly and the sharp edge will round over. Cool slowly afterwards.


Reply to
Cliff Coggin

A small diamond cutter mounted sideways in a rod with an adjustable stop. Rotate dianond on the inside of the tube to score an internal line and if it doesn't break immediately use a little gentle heat.

I doubt that the tube was weaker then.

Reply to
Neil Ellwood

Thanks Chaps

I hope this stuff is stronger than we used in chemistry!

Reply to
Classic Sales

Another method for larger-bore tube & bottles: rotate tube slowly about it's axis, heating evenly where the crack should run with a fine gas torch. Touch a wire with a drop of water on onto the heated ring, and the glass breaks cleanly around it. This might not work for model-sized sight glasses, though ;)


Reply to
Guy Griffin

Or you can do basically the same trick by tying a loop of string soaked in lighter fluid around the tube, set it on fire, and put it out with water after a few seconds. Works on bottles and suchlike.

-- Aamund Breivik

Reply to
Åmund Breivik

I seem to recollect whilst I was an apprentice the lab used high resistance wire looped across + - terminals on a 6 volt transformer. Obviously the length of wire would need to be calculated. Formula no idea. End result is the wire glows at red heat and cuts/melts its way through the tube leaving a nice edge requiring no smoothing to use. I hope some bright sparky can help with the formula. Cheers Dave

Reply to
Dave Jones

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