The displacer tube on my little Chinese Stirling engine developed a crack that left the displacer tube leaking air and the engine would no longer run.
I order some 12mm borosilicate test tubes from eBay, but these tubes are much to long for the engine and would need cut down to size.
I wrapped a piece of electrical tape around the test tube so the jaws of the lathe could get a grip on the glass with just the slightest of pressure.
To cut the test tube i used a 3 sided diamond coated file with the lathe turned down to a medium speed. the bed of the lathe was covered with kitchen towel to prevent any powdered glass getting on the lathe bed as it is quite abrasive. The diamond file must be used wet and water was also dropped onto the test tube as an extra precaution as the heat from the cut can dry out the file.
The cut was very clean and the small piece I though needed to be cleaned up was actually a piece of aluminium swarf that had stuck to the wet glass. the cut edge only needed a slight touch up with the diamond file.
The new displacer tube was then washed and dried to remove any remaining powdered glass.
The engine was then reassembled and after only about 10 seconds of warm up the engine was ready to run.
Post time: Jan-17-2017