Welcome to the second entry in this series of articles. Here I will discuss how to process a cast ingot of fine silver into a fine silver wire. CLICK HERE to learn how an ingot is cast! The first step in creating your own wire is having the appropriate starting material and the appropriate tool set to process that material into a wire. It may seem like a large list of tools but many of them can be fabricated at a fairly low cost and I will address that in this article as it becomes relevant.
Necessary Materials and Tools:
-A cast metal ingot or thick gauge metal wire/rod (click here to read an article on how to cast an ingot)
-Rolling mill (grooved for wire)
-Measuring tool (caliper or gauge plate)
-Annealing Area (fire proof work area)
-Wire Drawing Bench or some sort of tool that will allow you to “draw” your wire.
-Drawplate/s (round, square, oval it is up to you…)
Depending on your particular tool set you may need to start with a smaller piece of material and not such a large cast ingot. For example, you may not have a rolling mill that will allow you to process down a cast ingot, or a wire drawing bench that will allow you to draw a thick wire but there are many ways to get around this. Using only a draw plate, tongs and a bench vice it is quite easy to produce a range of different wires, but you may need to start with a thick gauge wire and or a small cast ingot; this will become clearer toward the end of the article.
I will be starting with a large cast ingot. After cleaning and drying the ingot, take it over to the rolling mill. If the ingot is too large to pass through the widest opening of the rolling mill it may be necessary to open the rollers to allow the ingot to be worked. Some wire rolling mills do not have this ability and if this is the case you may have to forge the ingot down or start with a thinner material (like a thick wire/ rod). Several ingot molds come in different size and designs that allow you to cast small ingots of wire ready to be rolled through a mill.
In this picture you can see my cast ingot and wire rolling mill. Notice that the rollers of the mill are not pressed together; this is because I have opened the gate of the rollers wide enough for me to pass the widest point of the ingot through the mill. In this position the ingot can pass freely through the largest groove in the mill. Once the rollers are spread far enough apart, we can begin to process the ingot down.
With the ingot out of the mill (never tighten the rollers with material in the mill) begin to tighten the rollers closer together; only by a quarter to a half turn at a time (this will often depend on the malleability of the material you are working with). After every quarter to half turn test to see if the ingot will pass through the widest opening. If the ingot still passes through freely, tighten the rollers by another quarter to half turn, until the ingot will not pass through the opening.
Once the ingot can no longer pass through the rollers, the ingot can make its first real pass through the mill. Place the ingot up to the opening that it was previously able to pass through and turn the rollers with the hand crank to pass the ingot through the opening. When the rollers are correctly positioned the material should be rather easily forced through the rollers and worked on the two sides that where in contact with the rollers. As the ingot exits the other side of the mill it should be retrieved and sent back through the mill with the rollers in the same position but with the ingot rotated ninety degrees (or a quarter turn); so that the two sides that were not in contact with the rollers may now be worked. If we neglected to do this, we would only work two sides of our ingot and it would not turn into a proper wire; as all four sides of our wire need to be worked evenly.
The rollers are slowly working the material and moving closer together one “pass” at a time. Notice how the material appears to bulge out of the sides of the groove it is passing through. This is precisely why we must rotate our material…
Continue to make additional passes through the rolling mill always tightening the rollers by the appropriate amount for the material you are working with after each pass. Remember that every “pass” is made up of two parts. The easiest way to think about it is if you were to always stay on one side of the rollers. A complete pass would consist of (part 1) the material passing through your side of the rollers, coming out the back end, (part 2) the material making a ninety degree rotation and coming back out of the rollers toward your end again. At which point the rollers can be tightened by a quarter to half turn and another pass can be made.
Here you can see the rollers are pressed together and the ingot has been transformed into a square-like octagonal wire.
After making several passes the rollers will meet and should be pressed firmly together and stay in this position for the remainder of the work. When I am producing wire for my work I will process an ingot of fine silver down to this thickness before annealing. The general rule of thumb I was taught to go by, is to work your material down to half its original thickness; at which point it should be annealed before continuing work. For this reason it may be very useful to keep a measuring device handy to keep track of the thickness of your material as you work. In my case, I know that the point at which my rollers meet is just about half the thickness of my original ingot, so things work out pretty well for me in this case; particularly with fine silver which is so forgiving, if this was sterling or some other material I would have probably annealed the material at least once before reaching this point. Note that we don’t have to anneal our ingot at the beginning of this process because it was recently cast and had not undergone any forceful reorganization of its crystalline structure; until we began to roll it through the mill.
To anneal our metal we want to heat it up and there are a few different ways of doing this… I use my torch, usually with a fairly large bushy flame. Different metals may have different visual indications of when they are annealed. In this case, fine silver usually appears as a very frosty white when annealed. If you notice closely at the picture above you can see the transition beginning to happen as the end closest to the flame is a dull white compared to the end in the foreground of the picture which still has a metallic luster from being “cold worked” through the rolling mill. These color indications show that the metal is at the appropriate temperature and not all metals should be heated to the point that it begins to glow red as this is usually an indication of approaching the melting point of the material.
After your material has been properly annealed you can return to the rolling mill for further processing.
Since my goal is to make a wire fine enough to produce filigree with, I will be taking this wire to the very last (smallest) groove on the rolling mill; I am taking it as far as I can on the mill because it is faster to pull material through the mill than through a draw plate.
Remember which opening / groove you had just come through before annealing and proceed to the next one. In the picture above you can see that my ingot (now my rod/wire) had passed through the tight rollers of the biggest groove before annealing so now we are on to the next groove. Now that the rollers are pressed together there is no need to adjust the height of the rollers, you can simply move on to the next groove after making a complete two part pass through each groove as you go; be sure to anneal your material after it has been reduced to half of its thickness (after annealing) as a general rule of thumb (some materials may require annealing after each groove!). On my rolling mill, I tend to go through three grooves and then re-anneal the material. In the case of fine silver, I could probably get away with more but I don’t want to over-stress the material; particularly when going as thin as filigree wire.
Wire can be rather uncomfortable to work with as it can take up a lot of space at times, make sure you give yourself appropriate room to work with. Eventually after making enough passes through the mill it may become very tricky to pass such a long piece of material through the rollers as the material may want to turn itself while passing through the mill. To avoid problems like these, I will usually try and keep the wire that is going through my mill at a comfortable length. To do this I will cut my wire in half as soon as it becomes too awkward to work with (like the really long wire in the picture above has become).
As you can see in this picture I am cutting the wire in half to fit on my annealing station.
After cutting, annealing and doing more passes through the mill your wire will become so lengthy that you can begin to spool it. There are many ways to easily make spools. The simplest method is to wrap the material as evenly as possible around the palm of your hand and to wrap the ends over the bundles to keep the spool neat. The most important part of making spools is keeping the bundle tight and even so that no separated (larger or smaller loops) pieces of the wire get overheated or melted during annealing.
Once our material is maybe a millimetre or two away from the desired thickness we need to stop using our rolling mill. Remember that the rolling mill only works two sides of our wire at a time and that it produces a funky square-like octagon, not a truly round or square wire… To actually make our wire into a nice clean shape we need to move on to a different tool and we need to allow the wire enough extra material to properly transition into the correct dimension. For example, if you needed to make a 1mm round wire but you already rolled your wire through the mill to 1.1mm square/ octagon, the wire will not have enough excess material to transition into a round wire of the desired diameter.
In order to produce truly round or square or whatever other shape wire you desire, we need to pass our rolled wire through a draw plate. Draw plates come in many shapes and sizes and the one you will use, and at what point you transition from the mill to the draw plate, depends entirely on you and what the final desired wire is. As I mentioned earlier, I want to make filigree wire which is very thin and fine so I will be using a draw plate with very fine round holes.
Important: Whenever you transition from the rolling mill to a draw plate make sure your material is annealed as it will undergo an extreme amount of stress and needs to be as malleable as possible for this transition to occur.
In order to get your wire into the draw plate you will have to file a taper onto one of the ends of the wire. Alternatively, if your wire is still on the thick side you could simply pass one of the ends through a smaller groove in the mill to step/taper the end a bit. In my case I need to file as my wire has already gone through the smallest groove of my mill. Once you have a good taper on the end of your wire you can begin to figure out which hole in the draw plate to pull through. In order to do this, use the same method you used with the rolling mill; find which hole the wire slides through easily and pass the wire through the hole just smaller than it can fit through. To pull the wire through the draw plate, insert it through the back side of the draw plate (the back side has the conical openings and usually lacks numbers) via the tapered end and pull it through using tongs or pliers via the front side (this side usually has numbers on it).
This is where you can cheat the system a bit, if you don’t have a rolling mill or wire drawing bench but still want to draw your own wire, this is how… Once you have a thin enough wire particularly of soft materials like pure gold, fine silver and copper, the extra force of the rolling mill and wire drawing bench are no longer necessary as the wire can be manually pulled with a pair of tongs through a draw plate placed in a bench vise. Since the length of wire I can make on my wire drawing bench is limited, and I want to make as much filigree wire as possible at one time, I will be pulling the rest of my wire this way; even though I do have a wire drawing bench. The mill and bench are really only necessary to process harder materials and thick stock material. If buying a thicker gauge wire from your supplier is cheaper than paying for more length of a thinner gauge, then being able to process the wire down to different sizes using what you have, could make drawing your own wire very useful. In my case, there are not many places in Costa Rica where one can purchase already made wire (especially of trust worthy, quality material) so fabricating my own wire is not only a good idea but a necessity.
Once your wire is in the correct hole of your draw plate, grab the end with your tongs and begin to pull it through. Note that if I were pulling this wire on my drawing bench this would probably be the maximum length I could achieve.
Although they do have a limit on length, wire drawing benches are extremely useful tools for creating thicker wire gauges that one cannot pull by hand. Another good way to cheat the system is to fabricate your own bench as I did. It is a very simple machine and can be made quite easily and inexpensively out of almost any material; although metal is almost always preferred due to its weight and strength, as a wire drawing bench needs to be very sturdy and heavy. They usually operate by means of a hand crank which pulls a pair of tongs across a surface thus multiplying the amount of force you exert on the pull and thereby allowing you to create thicker wire than you could pull by yourself. My bench utilizes a very basic winch as a crank which tightens a steal cable that has a pair of tongs attached to it (for a closer look at it and its construction please CLICK HERE).
Back to the actual wire… Keep going through the different openings of your draw plate as we did with the rolling mill and don’t forget to anneal after every few passes. Fortunately unlike the rolling mill the draw plate works our wire evenly on all sides so we only need to pass through each hole once. If the wire is difficult to grasp with the tongs, try giving it a tug to help it along with a pair of simple pliers.
Continue this process at least until the wire has transitioned into a proper shape; but of course you may want to continue until you have reached whatever specific dimensions you desire, whether that be length, shape, diameter or what have you.
Once your wire has reached its desired dimension/s it is almost ready for use. There are only a few more last minute details that I would like to include. If you would like your wire to remain firm and rigid (say for a pin back mechanism) don’t anneal it, but if you are going to be manipulating your wire a lot and need it to be flexible be sure to anneal it before working with it. You may also want to briefly pickle your wire to clean it of any oil or other unwanted residues, besides pickle you could also wash the wire using soap and water; you could also brush the wire with a scotch bright pad although this may leave a very subtle texture on your wire.
And that pretty much sums up how wire is made. I hope you found this entry to be useful and informative and I hope you return for the next entry. Third Entry: How to Roll Sheet Metal (Making Gold Foil/Leaf) CLICK HERE! If you have any questions please feel free to contact me or leave a comment.
Daniel Icaza 3/20/11