Step 1: Getting the Right Size Rod
Jewelry catalogs sell selections of straight rod mandrels for $50 or more, but my choice is from Harbor Freight. They have a set of 28 sizes, from 3/32 inch to 1/2 inch, for under ten bucks. It's called a Transfer Punch Set. The catalog number is #3577. www.harborfreight.com
Step 2: Winding the Rings
To wind a coil, just bend a right angle on the end of the wire about 3/8 inch long and insert this into the screw gun chuck. Then wind slowly, keeping a tight coil. I like to rest the end of the mandrel on the edge of the table or bench pin.
One note of caution - if you are winding an entire length of wire, be careful as you get near the end of the wire. If the end passes under your thumb, it can cause a nasty scratch or cut.
Step 3: Cutting the Rings From a Coil
I've seen all sorts of suggestions for ways to hold the coil, but the one that works best for me is this little jig made from scrap wood. It's about 2 inches wide and 4-5 inches long with a groove cut down its length to cradle the coil of wire and a thin stop attached to the front end.
To cut the rings, use a fine blade like a 6/0. Thread the saw blade through the coil, hold the coil down in the groove and against the front stop. Tilt the saw at a 40 degree angle as shown. Saw frames and blades can be found at jewelry supply companies like www.riogrande.com
Don't forget to use some wax or oil on the saw blade. It really does make a difference. If you don't believe me, do an experiment while you're cutting some rings. Count how many rings can be cut before breaking a blade, first without lube and then with some every 6-8 rings.
That's all there is to turning out jump rings quickly and easily. More of my jewelry tips can be found in "Bench Tips for Jewelry Making - 101 Tips from Brad Smith" on Amazon.