Chain Maille Jewelry Making: Understanding Aspect Ratio
Ah, chain maille. We meet again. (Can you hear that woo-hoo-woo sound they play in old Westerns, just before two cowboys have a shoot out? No? Just me? Okay. . . . )
I get a little nervous whenever it's time to write about chain maille jewelry. A good lesson I've learned, however, is that you don't have to know everything as long as you know how to find out the things you don't know. I love sharing my jewelry-making experiences with you, but when it comes to chain maille, I enjoy sharing someone else's experiences–someone who has the patience and skill to actually do chain maille! So today we have a lesson in aspect ratio, courtesy of Karen Hung.
A Little Math = A Lot of Success in Chain Maille
Understanding Aspect Ratio
By Karen Hung
Knowing how to weave rings into intricate patterns is only half of the craft of chain maille. To make a great looking chain, you must know the optimal ring size to highlight the pattern. If your rings are too large, your chain maille is floppy, and the pattern is lost. Conversely, if your rings are too small, your chain maille is inflexible or may not be able to be woven at all. Many times you'll see references to ring sizes in books or websites, sometimes referred to as key numbers or more commonly, aspect ratio (AR).
The AR is the relationship between the wire diameter (WD) and inside diameter (ID) of the ring. As important as the AR is for chain making, there usually isn't one AR for any particular chain maille weave. With few exceptions, there is usually an AR range for most chains, and the number you choose is a subjective decision. When you see an AR range in the lower numbers, it indicates a tighter weave. Larger numbers indicate an airy weave. One important thing to remember–the real beauty of AR is that the ratio remains the same regardless of the wire you are using; gold to copper to galvanized steel, AWG or SWG, the AR is always the same.
Finding the Aspect Ratio
To get the AR of a chain you need . . . math. But the formula is very easy, and you will find yourself using it over and over when making chains. Here's the basic formula:
ID / WD = AR
Let's say you want to weave a Byzantine chain that you saw in a magazine, but you prefer to make it with a larger or smaller wire than shown. Looking at the AR formula, you can see there are only three data points needed to make all your chain fantasies come true.
Let's say the magazine chain is 16 AWG copper rings with an ID of 4.25mm, using this information you can do the AR calculation. (See Common Wire Diameters chart)
To find the AR of the magazine chain (16 AWG =1.29mm and 4.25mm ID rings), plug the numbers into the formula:
ID / WD = AR 4.25 –> 1.29 = 3.29
Now you know the AR of the magazine chain is 3.29. To make a larger chain, let's say with 14 AWG wire, you would use the basic formula, rearranged to use the numbers that you know to find the new ring ID for the 14 AWG wire.
From the chart, you know the diameter of 14 AWG is 1.63mm, and from your previous calculation you know that the AR for the magazine Byzantine chain is 3.29. Plugging in the known numbers into the formula, you can get to the new ring ID for a Byzantine chain using 14 AWG wire.
WD x AR = ID –> 1.63mm x 3.29 = 5.36mm
You will need a mandrel that will produce jump rings with as close to a 5.36mm ID as possible. The ring size for a Byzantine chain that looks the best using 14 AWG wire is made with a 7/32 (5.55mm) mandrel. Make a small sample before cutting all your rings.
Let's go down a wire gauge (18 gauge) and determine a new ring ID; the WD for 18 AWG wire is 1.02mm, and the AR for the magazine Byzantine chain is 3.29.
WD x AR= ID –> 1.02mm x 3.29 = 3.36mm
The ring ID for the 18 AWG wire comes out to 3.36mm. You may want to go down to the 3.25mm mandrel or up to 3.5mm mandrel. Your mandrels, your wire, the wire temper, or simply your preference will ultimately determine which size ring you think is perfect. Again, make a small sample, and adjust as necessary.
AR, Wire Mandrels, and Experience
Most of the time the AR you use to determine the ring ID works fine. But sometimes you will find that your chain maille is a bit tighter or a bit looser than expected, despite the fact that you've doublechecked your math. Your unexpected results could have been caused by a number of things including the real gauge of the wire, your mandrels or the wire temper.
You will find that not all wire is created or labeled equally, sometimes your wire measures perfectly when using a standard wire gauge, or sometimes it's a tad bigger or smaller than what it's labeled.
Silver, copper, and Argentium are all measured using the AWG in the United States. In Canada and the U.K., the same wire is measured using the SWG system. Additionally, the same gauge wire in different metals, or wire from different companies, may not always measure out to the same size.
If you use wooden dowels as mandrels for making jump rings, each time you use them they compress and will get a bit smaller, which further complicates the task of determining the ring ID for the chain you're trying to weave. You can buy steel mandrels made specifically for making jump rings, or you can buy a set of transfer punches (available in both metric and imperial sizes), or use aluminum knitting needles to use as your mandrels.
Wire temper is another part of hitting this seemingly moving target of ring ID. Dead-soft wire wraps up nice, but since it's soft it tends to dull your saw blades a bit faster than other wire tempers. Half-hard wire is easier to cut, but springs back a bit when you release the tension from your coil, making your rings a little bigger than rings made from dead-soft wire. Hard wire will spring back even farther than half hard–and spring hard wire is even worse!
Determining ring ID and making rings is time consuming, but making your own rings frees you to create your chain.
The best piece of chain-making advice is to buy some copper wire in a number of gauges and make prototypes of your chains. Document your favorite sizes. The time and wire used for making samples will serve you well. You learn the weave without worrying what your rings will look like after you've opened and closed each ring several times, you will find your optimal ring, and you will have a small piece of chain or tail to use to start, instead of having to start anew. –Karen
Now that you're armed with all the technical knowledge you need to understand jump rings inside and out (literally!), you must be ready for some great chain maille jewelry-making projects using them. Turn to America's favorite jewelry-making show, Beads, Baubles and Jewels, for your chain maille and other wire and metal jewelry projects and inspiration. The Beads, Baubles and Jewels series DVDs are on sale now in the Jewelry Making Daily Shop!
Karen Hung is an independent craftsperson working in Southern California. See more of her work at khmetalwork.com and on Etsy.
Originally published in Step-by-Step Wire Jewelry, Summer 2008
wire diameter source: The Complete Metalsmith by Tim McCreight