I've got some 42mm tube with 2.6mm wall. I'm trying to flare one end into an oblong shape. Ive made a die using round bar which is used with a 20t press. The problem I'm having is the tube cracks, even after heating red hot! So the tube needs to be flared to this shape: This is the die And these are the results: Would it be better if I used cds tubing? Also would it work better if I flared it out with a cone shape first to obtain uniform wall thickness, then hit it with the final shape?