Jump Ring Forming Device

Intro:

Jump rings are commonly used in jewelry making, metalsmithing and chain maille weaving. The basic process of making jump rings involves creating a coil of wire around a specific diameter mandrel and then separating the coils into individual rings using snips or a jeweler's saw. This device aids in creating the coil wires. Total cost: ~$50 USD depending on scrap wood availability.

Materials:

One 6" to 8" length of 2" x 4" (1 1/2" x 3 1/2") fir (length depends on desired finished height)

One 6" length of 1" x 4" pine (1 1/2" x 3 1/2")

One 1/2"-20 x 3 1/2" cap screw

One 1/2"-20 hex nut

Two 1/2" bore R8-2RS Bearing 1/2 x1-1/8 x5/16 Inch

One Keyless Drill Chuck 1/2-20UNF thread

One 4-inch Diameter Round Handwheel preferably with a 1/2" bore (I had to use a 12mm and bore it out)

One 4" C-clamp

Transfer Punch Set to use as wire forming Mandrels

Steel reinforced epoxy putty

Pocket hole jig and screws

Drill press and clamp for boring handwheel (if necessary)

Benchtop grinder or metal file

1/2" open ended wrench or crescent wrench

Measure down 1/2 the width of your stock from one end. Here, we're using a 2" x 4" so we measure down 1 3/4" from the top end of the main upright. Measure in 1 3/4" from one side to intersect with the first mark, This spot defines the center mark for the bearing races or insets. Make sure this is well marked.

If desired, layout whatever contour or shapes for the top and sides of the upright. Make sure to leave enough room for the 1 1/8" bearing insets and supporting upright material. I chose to round the top using a 1 3/4" radius. A plastic peanut butter jar lid happened to be close enough so I just traced around half of it.

I also chose to mark the spots for each of the four pocket screws used to attach the main upright to the base. Here, I just made marks 3/4" in from each side along the base end of the front and back of the upright. The use of a base is completely optional as the upright can be screwed directly to a benchtop or other work surface. Here, the base provides for a convenient clamping surface and provides portability for the jump ring former.

Drill a 1/8" pilot hole all the way through the upright at the center mark we created in the layout step.

Next, using a 1 1/8" forestner bit, carefully align the bit point with the pilot hole and drill a recess into the first face of the upright. I chose to stop at a depth of about 5/32" or half the thickness of the bearing. Flip the upright over and repeat this with the 1 1/8" forestner bit.

Next, using a 5/8" spade bit, bore out the center pilot hole. I have better luck going halfway through the remaining stock and then flipping it over to keep things centered and concentric.

At this point it is a good idea to do a dry fit. Insert the bearing in each of the two opposing insets and check to make sure the cap screw can be inserted through the bearings and turns freely. Once you are satisfied with the alignment, disassemble the bearings and cap screw.

Shape any desired contours. I chose to round the top and use a 3/8" round over bit in my router to smooth all but the bottom outer edges. Next, attach the upright to the base using appropriately sized pocket screws.

From the pictures you can see that I chose to shape the upright first before drilling. This really isn't optimal since that work could be wasted if the drill step isn't successful in getting concentric insets and bores.

Because I wasn't able to source a handwheel with the proper bore, I needed to drill out the handwheel bore from 12mm to 1/2". This can be tricky and a little dangerous, especially if you don't have access to a drill press, proper clamps and equipment. Without these, it would be more advisable to fashion a hand crank from wood or another material and affix that to the cap screw to complete the axle assembly,

Here, I used a high quality 1/2" metal bit in my drill press to increase the bore to 1/2".

Next, I used my benchtop grinder to create a flat spot on the upper end of the cap screw shaft to align with the key slot on the handwheel crank. The slot and flat spot will create a keyed void which when filled with epoxy should prevent the wheel from spinning on the cap screw. While this is probably the weakest part of the design, this is a low torque application and the connection should survive.

Next, mix a nickel sized slice or two of epoxy putty. Prefill the flat spot on the cap screw and the key slot on the handwheel with the putty. Insert the cap screw into the handwheel bore making sure the slot is aligned with the flat spot and the hex head of the cap screw is on the outside side of the handwheel - the side that the crank handle is attached to. Working quickly, try to compress as much putty as you can stuff into the flat spot and key slot as possible. Once it is cured it can be filed and sanded to clean things up.

Let this cure in a secure place as per the directions for the epoxy putty. Do not rush this step.

Attach the handwheel crank handle to the handwheel. Mine required an allen wrench. Insert a bearing onto the cap screw shaft (axle). Insert the handwheel and cap screw into the side of the upright which has the base extending from it. The wheel should be above the base clamping surface. Insert the other bearing onto the cap screw axle and press it into the bearing race on the other side of the upright.

Next, screw the hex nut on to the threaded end of the cap screw until it isn't quite finger tight against the bearing. Screw the keyless chuck onto the cap screw until it is finger tight against the hex nut. Using a crescent wrench or open ended wrench lock the hex nut against the chuck by rotating the hex nut counter clockwise. DO NOT torque the handwheel to assemble or disassemble any of the components.

With your jump ring former securely clamped to your work surface, chuck your mandrel and wire into the keyless chuck and hand tighten the chuck. Applying some tension to the wire, turn the hand crank to wind the wire around the mandrel. Start slowly until you get the hang of the best tension and wire angle.