I've seen people attempt to cut these tubes and fail and so I thought I'd give it a go to see what it was that was stopping them from making the cut. I've worked it out now of course. Given that these things are very difficult to secure, you can only get so far through the target before the imparted energy from the cut starts to move the target and then of course youve lost the majority of the force of your cut as the target moves with the sword. This and the fact that the moving tube changes the angle of the tube and the sword along with it, edge alignment with the moving angle simply stops the cut dead. You'll see ;)
Is this challenging? Abso-bloody-lutely. Will it wreck your sword? There is a possibility of mild edge damage so be careful. If youre using 1045, it will bend. So dont. Use 1060 or some other 'spring' type steel. anyway, enjoy my fails ;)