Larger jump rings can be spun on a wood dowel mounted in a drill. If
the dowel is larger in diameter than the drill chuck can handle the
end of the dowel can be shaved.
Shaving the ends of much larger dowels will not work. The wood will
break before any coil can be wrapped.
To solve this problem I tightened 4 nuts on a number 8 screw so that
all the flat edges of the nuts matched. Coated the nuts with crazy
glue. Drill a hole slightly smaller in diameter than the screw in one
end of the larger dowel. Make sure the hold is centered on the center
of the dowel. Place some epoxy or gorilla glue in the hole. Place a
flat washer on the screw and screw it into the hole until the washer
bottoms on the dowel. Let cure.
Cut a slot in the end of the dowel that is the width of the wire
diameter that will be used for the jump rings. Cut it about twice
the wire diameters into the end of the dowel.
Bend a 90 degree tab in the wire that will be used for the jump
rings. The tab should be shorter than the diameter of the dowel.
Place the nuts on the screw into the chuck of a variable speed
drill. Slip the wire tab into the slot in the dowel. Put a glove on
the hand that will be used to control the wire on the dowel. Place
your gloved hand on the wire and hold the wire tight against the
dowel. Turn the drill on a very slow speed. The gloved hand will
guide the wire onto the dowel.
Caution: do not wrap the wire to the very end of the wire. The last
part of the wire will not bend down onto the dowel and will remain a
sharp vertical tab that can cut the gloved hand.
I use a jewelers saw to cut the jump rings while they are on the
dowel. The jump rings are cut by the saw which is held at an angle to
the dowel so that the top of one ring is cut at a time. The remaining
portion of the coil can be slid into the saw as rings are cut off.
I will put photos depicting the above on my blog as soon as I have