I want to bend some 32mm O/d 1.5mm wall thickness aluminium pipe to make coolant lines for my kit car. I have tried a hydraulic bottle jack type pipe bender but this just flattens out the pipe, so how can I do this?
I did this years ago with steel pipe, same result as you.
I didn't need a passage through the pipe so I made some wooden discs fitted inside the tube to stop . It collapsing. Of course then they wouldn't come out.
I believe another method is to fill the pipe with sand, close off the ends (weld ends on temporarily? ) and then bend. I doubt you'll achieve a tight radius though.