Scoring and Bending
Scoring and bending is one of the most important ways of constructing jewellery. Scoring is a method of obtaining very sharply defined bends in metal sheets.
The angle of the bend is determined mainly by the amount of material removed from the groove. It allows rapid and accurate work to specific angles and parts being soldered stay in place during heating without falling apart. The grooved cross section can be arrived at numerous ways, my favorite being separating disc followed by needle files of the appropriate angles. Other methods include photoetching, chasing tools, chisels, gravers and other approaches mentioned later in this section.
No matter how one makes the groove for scoring you get essentially one chance to make the bend which is then flushed with solder. If you score and bend and find that your angle was not correct all is not lost. Flux the clean scored bend. Anneal. Place in hot running water to get rid of the flux (not pickle!). Bend it gently back flat without overbending at all. Complete any additional scoring that has to be done without stressing the bend. Reflux, anneal, remove flux in hot running water again and bend up. You only really get one chance to do this kind of thing.
Note the insistence on hot water instead of pickle. This is because pickled surfaces do not take solder well, do not induce solder to run into seams and do not fill well. Another approach which is fine with small objects but is not wise with scored seams over about 2 cm long is to flux and then heat to anneal. While the metal is hot one bends it up by pinching with tweezers. The metal is very mobile and forgiving in this state and one can sometimes make an almost right angle bend apparently become one by doing this. It takes some heat control however because too hot and it breaks and too cold and it breaks. You don’t ever want to lever back and forth on scored seams hot or cold.
A file tang may be easily converted into a scoring tool. This tool is extensively used in traditional box making and I would recommend it for scored straight lines longer than about 6 cm. The tang is heated and bent over, then air cooled and filed into the desired shape, usually a face like a beveled grave which faces towards the body of the file. The angle chosen represents the angle the bend will be made to. After checking to see that the tool cuts into metal and that the file provides a comfortable pulling angle for the hand it is hardened and tempered. The metal is ruled and the score started gently. It helps if the metal is clamped firmly down with C-clamps and little cardboard pads. I usually begin by drawing the file tang towards me gently against a metal fence clamped to the metal as well. Clamp everything to a disposable board of wood as when the tang point comes off your metal it digs into whatever it is on-better the board than your desk. One turns everything around at least once so that there is an even depth to the cut. One always tends to put more pressure near the end of the pull. It is gone over many times, until the cut is almost through. A raised line will show on the far side when it is about right. I’ve used this to cut large sheets of metal quickly by grooving it using a plank as a fence and then, standing on the plank bent the sheet back and forth several times until it broke off cleanly. It was very fast.
Silicon carbide separating discs are superb for scoring metal for bending, particularly when the metal sheet is less than 4 or 5 cm across. One usually follows up with the appropriate angle of needle file or another scoring tool. While I was originally taught to use discs for catch building which involves only straight lines I discovered that they are superb for curved line scoring. Advantages include no disturbance of a textured sheet metal front surface while gaining enormous changes in plane. This is how many of my own pieces are done. Basic tips for scoring with the disc include: anneal the metal before you begin. Do not press hard; if the disc wears quickly you are pressing too hard. The disc is very hard (nine and a half-it will cut ruby and sapphire) but brittle. Let it cut its own way. Wear safety glasses and breathing protection-the dust is not good for you. Let the disc drift gently away from you (right handers), if you pull it towards you it will tend to sink rapidly through the metal. Go over the same area a number of times. Because the disc wants to leap over the edge away from you and come back on the other side lift the disc off before you arrive at the far edge and turn the metal around so the part near the edge is towards you before continuing. When you see a raised line on the other side it is time to stop. If you go through burnish it closed before soldering.
Separating discs are also great for short run scoring and bending like making bezels for fancy cut stones or angular structures. Assuming a strip of metal up to a centimeter wide and about a millimeter thick one scores most of the way through until the raised line appears on the far side and then folds the metal up. From the cut side one takes a regular sawblade in a sawframe and gently cuts outwards towards the corner. Then the strip can be further bent. This is repeated until the exact angle needed is arrived at. Then one solders the join and proceeds to the next bend. In this way it is a very quick matter to fabricate an accurate angular strip construction. If you have a little experience you can usually do two to three cuts and bends before soldering them at the same time.
One often uses needle file; to widen scored lines to specific angles. Often this is a right angle so one needs a 90 degree angle. However if a square needle file is used one tends to rock it slightly and so the angle obtained is too large. If one were to use a 60 degree triangular needle file then one can work up towards a right angle with far more control. The last few strokes are then done with the square file. It is better not to count on perfection in working.
I have found that if one breaks off the ends of a square or triangular needle file and grinds them to the same angle as a graver they become a file-graver combination;. They can widen a separating disc cut or other scored line to an exact angle. Held at one angle they are a file and at a slightly different one they are a graver which saves having to pick up and put down a tool.
Karen Cantine from Edmonton, Alberta has developed a method of scoring for holloware construction that is called ‘.i.planish scoring;’. She takes a piece of metal and holds it against a right angled edge and then planishes with a slightly crowned planishing hammer against the edge, until the line shows almost all the way through. The metal is then annealed and folded into shape. This gives very quick crisp angled bends similar to construction in outward appearance. One can with judicious use of curved right angled surfaces also produce curving scored and bent surfaces with this approach. I’ve planished onto a chasing tool for a similar effect.
I use soft iron binding wire or hard brass 20 g wire for scoring and bending. I press it most of the way through the metal with the rolling mill, anneal and bend up. It does straight lines and curves. One can also tape the wire on to the metal and then planish it in for scoring, bending and decorative effects.