This article describes some tips on the using methods of closing jump rings as written by Charles Lewton-Brain.
When attaching a jump ring to a chain, hold the chain about 3/4 of an inch from its end and dangle it from your fingers. You can snag it onto the jump ring easier this way than by grasping the last link and trying to hook it onto the jump ring.
To close jump rings, hold chain-nose pliers in your dominant hand and hold flat-nose pliers in your other hand. Use the flat-nose pliers to steady one side of the jump ring and tighten the loose end closed with the chain-nose pliers. This process shouldn’t dent or damage the jump ring wire.
In high volume production operations, many jump rings need to be closed one after another. For such fast paced operations, pliers simply won’t do. Factory workers need efficient tools for closing jump rings. One such tool consists of a ring that has a slot head on it for gripping and steadying a jump ring (see photo). To make it, you will need a brass or silver ring that fits on the index finger or thumb of your non-dominant hand. You also need a rounded, slot head screw. Make sure the gap in the screw head is the same diameter as the jump ring wire you intend to close. If necessary, enlarge the gap by carving it wider with a separating disc, or make it smaller by soldering a thin shim into the slit. Cut the head off the screw with a jeweler’s saw and solder it onto the ring.
The slot head now takes the place of one pair of pliers normally used to open and close a jump ring. Place the jump ring into the slot head and use the pliers to manipulate and close the ring.
Another version of this jump ring closing tool is a ring with a slit in it. You can keep multiple rings with various size slits to fit different jump ring diameters.
Another tool for closing multiple jump rings quickly is a special punch made to fit a specific size jump ring. The punch is made from a round steel rod and it has a concave domed hole in one end, similar to a tube setting bezel rocker. The jump ring of the desired size fits exactly into the dome. When the punch is struck over a jump ring, it automatically closes the jump ring tightly.
To make the punch, anneal a round rod and drill up into the center of it (about 3 to 5 mm) with a small drill bit. Use a large round bur to carve out a concave domed hole in the end of the rod. (The drill hole keeps the bur centered as you carve out the shape.) You can polish the rounded hole with a piece of soft wood; a disposable chop stick works well. Set the wood into a flex-shaft handpiece and press it into the end of the punch. Using a polishing compound together with the wood makes the concave end mirror bright and smooth, preventing damage to the jump rings.
Choose the jump ring size that you plan to close with the punch. Close this jump ring using pliers and set it into the concave end of the rod. File back any metal that protrudes past the ring; the jump ring should be flush with the end surface of the rod.
To close rings in quantity, throw them onto a surface plate, anvil, or pad and tap them closed with the punch. Because they fit flush into the end of the punch, the jump rings are closed neatly, quickly, and securely. I sometimes use a hard rubber pad, such as a urethane pad used for hydraulic die forming. The pad wells up into the end of the punch, forcing the jump ring closed.