Saws and Saw BladesPosted Jan 26, 2010
In the early 1980s, I worked as a bench jeweler for an old family business with a customer base that stretched back a couple of generations. Occasionally a remarkable antique ring would come in for repair, always platinum or white gold embellished with a series of tiny sawed out shapes that formed a pattern and intricate linear scrollwork. This pierced work was so intricate and in the best cases, so perfect, it was difficult to imagine someone actually sitting at a bench and doing the sawing.
When I asked how this kind of work was humanly possible, my fellow jewelers laughed. They told me they didn’t think anyone did it, at least not anymore. Why? Because, they said, all the good saw blades from the 1920s, 30s and 40s had disappeared. Before World War Two you could get saw blades from Germany that cut metal so cleanly, so accurately and so easily that complex pierced work was possible. But the formula for those magical blades was a well kept secret. During the war, metal manufacturing was completely given over to weapons. When the war was over many wonderful things had been lost, including this mysterious formula for the perfect saw blade.
Even if no one has reinvented those fabulous and perhaps mythical German saw blades, better blades are available now than those that existed in the 1980s. You can saw if you slow down, keep your saw vertical and follow a few simple rules.
Jeweler’s saw blades are always a compromise between hardness and flexibility. The hardness allows the teeth of the blade to retain their sharpness and cut cleanly with minimal work on the part of your arm. Flexibility keeps the blade from breaking if it happens to move out of a vertical alignment with your work. When you buy more expensive blades you’re paying for an optimum combination of flexibility and hardness, evenly spaced blade teeth and equal length of each tooth. Cheap blades tend to be more brittle and have missing or uneven teeth and therefore break more easily and don’t saw as smoothly. But if you’re a beginner, you’re going to break blades whether they are cheap or pricey, so start with the cheap ones until you get the hang of sawing.
Tips For Easy and Accurate Sawing
- Use the right size blade for the gauge of metal you’re working on. The rule of thumb is two blade teeth per metal thickness. A good jewelry tool catalog will recommend the correct blade for any given metal gauge. A 4/0 is a good all around blade for cutting 20 and 22 gauge sheet metal.
- Keep tension on the blade. Insert the bottom end of the blade into the saw frame and tighten it. Then compress the saw frame between your chest and bench, insert the blade at the top of the frame and tighten it. When you release the saw frame, pluck the blade like a guitar string. It should ‘ping’, indicating the right tension. Lack of blade tension makes it difficult to control the path of a saw cut.
- Saw on a flat surface and use a flat bench block with a slot about three inches long cut into it. The slot can be a ‘V’ or a long open strip with a circle at the end. Work toward the end of the cut so you can support your metal on two sides with your thumb and forefinger. If the metal tips or moves, you risk breaking a blade.
- Keep your saw vertical in relation to the metal you are cutting. That means, keep it straight up and down. As long as the saw remains vertical in every direction, from front to back and side to side and has the correct tension, you won’t break a blade. But remember, everybody ends of with a bone pile of broken blades at the end of a complex sawing project!
- Use a lubricant such as beeswax or a brand name like Burr Life to begin sawing. Start with a down stroke. If you have trouble beginning a cut, you can position your metal so the edge to be cut into lines up with the edge of your bench block. That means you’re sawing wood and metal simultaneously. This tip of sawing wood and metal is also good for ending a cut. This is especially helpful for thin metal, like 26 gauge.
- Move the work into the blade, not the blade into the work. The saw should stay in the same position throughout the cut. Don’t push the saw or tip it forward. Move it up and down and let the saw teeth do the work. Your job is keeping the blade on the line to be cut and in a vertical position.
- Keep in mind that the actual cut happens on the saw’s down stroke. The upstroke simply gets it into position for the next down stroke.
- Despite their best efforts, most people, including me, saw with a blade tilted slightly to one side. If you begin a work sawing counterclockwise (if you’re right handed you probably begin this way) your cut metal edge will have a tilt to it as well. If you go in from the other side and saw part of the piece clockwise, the tilt will be in the opposite direction. If the two meet, there will be a slight discontinuity that must be corrected by filing.
- Turning a corner too fast is an easy way to break a blade. To turn a corner and not break a blade, saw to your corner, then saw in place until you’ve made a sawed out space just big enough to turn your blade in. Make your turn and proceed.
- Pierced work (like that in the old rings I love so much) is done by drilling the smallest hole into the metal that will accommodate your saw blade, inserting one end of the saw blade, then tightening and sawing as usual. Make sure your drill hole is away from the line you’re going to cut. Moving slowly, using the smallest possible blade and keeping your blade vertical will help you make the most accurate piercings, ones that require little or no filing later.
- You can use a saw to clean up a line too thin or a pierced area too small to insert a file. Just insert the blade and very carefully with short up and down strokes, saw repeatedly along the line to be cleaned up until the unwanted metal is gone.
- Always keep your eye on the blade and how it relates to the line you’re cutting!