If your doing anything complex, consider a copy of the Bend tech software. The cheapest version is something like 60.00 bucks.
Check out:
http://www.2020softwaresolutions.com/index.htm
I have no affiliation, just a happy customer. I used it to nail a bunch of tricky bends for a tube frame car I built a while back. Takes all of the guesswork out of things.
Vin