Mike: I cut them off using the lathe and a 1/8 inch air micro grinder with a diamond cut off wheel from Harbor Freight.
I spiral wrap masking tape around the tube and chuck it lightly in the lathe. Put the micro grinder in the boring bar holder for my QCTP. Slowly feed the diamond wheel in with continuous lubrication. The length of the shank on the cut off wheel dictates the amount off cut.
Jan Ridders website I believe has plans for a dedicated cut off fixture. For me the need doesn't arise to take the time to build a specific tool.
Hope this helps. If you have any questions don't hesitate to ask.
Roger
