Get a tube-cutting jig.
This simple (though finicky-looking) device holds rod and small tubing* in a v-channel, so it won't roll out of place. It includes a pressure clamp to assist work holding and a positive stop - just set the stop, and when you bump your material to the stop you're prepared to cut multiples of the same length. Think about this tool for making rivets and eyelets (and tube-settings for round gemstones, if you're ready for the next level.)
*The jeweler's term for small tubing, usually in a semi-precious or precious metal: chenier
In this case I'm helping my friend Kyle make 30 or so blanks for eyelets. We were working on this project.
Guess where I did all of this? Techshop Detroit! www.techshop.ws
Step 1: Tools and materials
Bottom: Tube-cutting jig (bought from a jewelery supply - do a search and you'll find one)
Not Pictured (incredibly enough): Tube material