A while ago I had to turn a copper disc to fit the end of a hot air engine cylinder and puzzled over how to hold it. My first attempt consisted of sandwiching it with double sided tape between a flat ended mandrel held in the chuck and a thick disc on a live centre in the tailstock - this worked ok until the job warmed up a bit softening the tape. I then replaced the tape with araldite, left to cure overnight and successfully completed the job taking very light cuts.
That was about 2" in diameter and I now have to repeat the process for a 5" disc - is there a better way to securely hold the work?
TIA for any advice.