Use a disc cutter to create a flat washer, and then turn it into a seamless ring in a few easy steps. I use sterling silver sheet here, but you could substitute it for any metal that is soft enough to form with a mallet, such as copper, brass, or mokume gane. I'm creating a plain ring, but you could also embellish the washer with designs before forming.
The process is simple and involves just a few tools:
1. Swanstrom Disc Cutter Set - Available here at riogrande.com
2. 18-Gauge Sterling Silver Sheet - Available here at riogrande.com
3. Ring Mandrel - Available here at riogrande.com
4. Dead-blow Mallet - Available here at riogrande.com
Step 1: Select the Inside Diameter of the Washer.
Select the inside diameter of your washer. The inside diameter corresponds to the size you want your ring to be. A 1/2" inside diameter will produce a ring that is approximately a size 8.
Slide your piece of sheet between the cutter discs under the hole size you’ve chosen.
Step 2: Cut the Inside Diameter of the Ring.
Be sure to use a shim (or wedge) to ensure a clean cut. Your shim should be the same thickness as the metal you are cutting. Slide the shim between the discs opposite the sheet you will be cutting. Tighten the disc cutter using the handle on the top. With the brass-head mallet, cut the inside diameter using the correctly sized punch. Use one or two firm strikes of the mallet to make the cut. Using more than one or two strikes can cause the sheet to shift in between strikes, resulting in an unclean cut.
Step 3: Cut the Outside Diameter of the Ring.
Determine the outside diameter of your ring. The larger the outside diameter, the wider the ring will be. A 1" outside diameter and 1/2" inside diameter a will produce a ring with an approximate width of 6.2mm. Move the sheet to the corresponding hole size you have selected for your outside diameter.
Step 4: Choose the Die.
Use the appropriate center-positioning die to center the small hole in the larger sized hole and tighten the disc cutter.
Step 5: Cut the Outside Diameter of the Washer
With the brass-head mallet, cut the outside diameter of the washer. Again, make sure to make the cut using one or two firm strikes of the mallet. This will ensure a clean cut and require less finishing work later on.
Step 6: Remove the Washer.
Remove the washer from the disc cutter.
Step 7: Place the Washer on a Ring Mandrel.
Set the washer on your ring mandrel. If you have a design that you want on the outside of the ring, make sure the side of the washer with the design on it is facing toward the tip of the mandrel.
Step 8: Flatten the Washer.
Using the dead-blow mallet, flatten the washer around the mandrel. Work your way around the entire washer, maintaining firm downward pressure on the washer as it stretches and moves down the mandrel.
Step 9: Finish Shaping the Ring.
When the ring is nearly flat, flip it over on the mandrel and finish shaping. Flipping the ring over on the mandrel a couple of times as you form it will prevent one end from tapering. Smooth the edges with a file and polish to your desired finish.