In my experience the best way to bend a tube is this:
Cut the piece you are bending a little bit longer than you need, you
will cut away a little bit of excess after bending as it will kink a
bit. For example, if you want the tube to be 30mm, cut a 40mm piece
to work with.
You will need a bracelet mandrel. I use an oval one, at the largest
You will need needle files (the handle ends) or something else that
fits snuggly inside the ends of the tubes.
Anneal your metal.
Mark the center of the tube so you know where it is with a scribe -
this might come in handy later.
Rest the bracelet mandrel on a stable surface. I put mine in my lap
with the end resting on my bench pan. Put the needle files in just a
bit (a couple mm’s not too far)
Use your thumbs on the needle files to evenly bend the tube around
the mandrel. You may need to practice a few times.
Cut the ends off.
Hope that helps!