Then I choose the size mandrel I need. I use knitting needles for mandrels.
The next thing I do is insert the mandrel and wire in my drill. I make sure they are in the chuck nice and secure and then I ever so gently press the drill trigger while guiding the wire with my left thumb and index finger. I use extreme caution as the wire comes to an end. It is very painful if the end of the wire goes through your fingers. (Yes, I speak from experience).
And this is what I end up with - a coil of wire.
I then saw the coil apart using my trusty jeweler's saw - which has a blade as thin as a hair. It is very important to keep the blade lubricated so that it doesn't break. I use beeswax for this.
TA-DA!! The sawing is done and I end up with a pile of rings. Ready to create.