Cutting glass tubing on the lathe (16/11/10)

The "traditional" way of cutting glass tubing is by scoring and snapping it. This technique works well for small-diameter tubing and long lengths of large-diameter tubing where you have sufficient leverage on the tube to break it. However, it's pretty useless for cutting the likes of test-tubes into short lengths, as was required for the Houskeeper seal. The other way of cutting tubing which is widely described is to make a scratch right round the tube and then heat it using a heated wire. This does work, but it requires a hefty current source to heat the wire quickly enough, and it has problems with uniform heat transfer from the wire to the glass.

A method which overcomes these problems is to make the scratch on the lathe and then use a micro torch flame to sharply heat the scratch as it's rotating. I have used this method to cut lots of 1" test-tube glass into a variety of lengths, some as short as ¼". It works with both soda-lime and borosilicate glass. I made a video showing the process, see below. The torch used is the little micro-torch I made and is using an oxy/propane mixture.

22/11/10: I later discovered a much better way of scoring the glass on the lathe. Instead of using the point of the carbide tool, I used the corner edge of the long 1/8" square carbide blank. This still made a perfect scratch around the tube, in fact probably a better scratch, and the edge of the carbide blank lasts a lot longer than the point. It's really just like a proper carbide knife which is what's properly used for this job!

03/05/11: I recently discovered the company Adams & Chittenden Scientific Glass, from California. They have an absolutely wonderful website at, with loads of information and photos of various glasswork. More relevant to the content on this page, they also have a great video of cutting large-diameter (over 30cm!) glass tubing using the scratch-and-heat method. Check it out here (MOV file):

16/05/11: Here is a better video showing how to use the edge of the carbide blank, as described above: