Sawing Essentials

Sawing Essentials
by Helen I. Driggs, Senior Editor, Lapidary Journal Jewelry Artist magazine


 

Don't Leave Good Blade Karma to Chance

The saw frame is typically the first purchase made by the aspiring jewelry maker. It is the most important tool to acquire and master because sawing and piercing are basic operations for all metalwork. It is important to practice sawing without a thought of a finished piece until you're confident you can follow a line, turn both inside and outside corners, cut along complex curves, and cut all thicknesses of sheet in all metals.

The best way to start is to choose a saw frame, get a few dozen blades in a range of sizes, and buy five or six small sheets of metal. I suggest aluminum, copper, brass, and bronze because they all saw differently. Start with 20-gauge and work down to 18. Then try 24 or 28-gauge. And trust me--save the silver for later, when you know what you're doing.

I'm including practice patterns and instructions for cutting them out. Follow the photos for learning to thread, hold, and use your saw. Don't freak if you break a blade--everybody does. You may find you love to saw or you may find you hate it. If you hate it, get over it--unless you really want every piece of jewelry you make from now on to be standard, mill-cut rectangular or square!
Don

Purchasing a Frame

There are two types of frame: adjustable and stationary. Most makers prefer the adjustable frame because short lengths of broken blade can be strung and used until completely worn out. This is a good feature when you're new to the saw because you'll probably break many blades when learning. A stationary saw frame will only accept full length blades, so these are best purchased by an experienced maker. Once you get the knack of sawing, you'll only break a blade occasionally--unless it's a dreaded, bad-blade-karma (BBK) day, in which case you should go do something else in the shop for a while. Recognizing and accepting that you're having a BBK day is humbling but also one of the most important things to learn about sawing. Everyone has them once in a while, so don't think it's just you.

Some frames allow the blade to be rotated in an arc away from the cutting line. This allows you to relocate the back bar of the frame away from the kerf (the cut, more on that later) and to use a larger piece of sheet. This kind of frame is handy if you cut strips or lots of cuff bracelet blanks.

Saws come in several standard throat depths ranging between about 3'' and 11'' in depth. A 4'' frame is a good starter size and will allow you to cut typical sheet sizes available from most suppliers. If you've never sawn before, look at this graphic and familiarize yourself with the parts and mechanisms of your frame.

Know Your Saw

Practice Pattern

Practice Pattern Photocopy this pattern at 100 percent. If you're right-handed, saw in the direction of the RIGHT arrow. If you're left-handed, saw in the direction of the LEFT arrow.

How Blades Work

Sawblades don't really cut. They actually weaken and then chip small particles of metal away. Take a close look at a blade directly at the teeth (use a magnifier if you need to) and you'll see they alternate left and right in a predictable pattern called a set. This arrangement allows the chips of metal to fall away on both sides of the blade. The distance from the outer point of the right teeth and the outer point of the left teeth is the blade thickness, and will determine the width of the kerf--or ''cut'' opening you make with the blade. Finer blades make a narrower kerf. How Blades Work

What You'll Spend

  • 3'' sawframes run between $10 and $35 depending on where they're manufactured and who you buy them from. Try to buy a quality, hardened tool steel frame with a contoured wood handle.
  • Blades average between $1 and $6 a dozen--again, you get what you pay for. When you're learning to saw, start with good blades even though you'll destroy them. Good ones usually break only because of bad technique. You can learn to correct your technique, but you can't correct poor materials, so why struggle with something you can't fix?

Threading the Saw

Sawframes are engineered to hold the blade under tension. To create tension, a series of thumbscrews, pads, and washers allow minute adjustments to the frame depth, length, and the amount of pull on the blade. Here is how to thread the blade properly into your frame.

Threading the Saw Image 1 Pick up a blade. Look at the teeth. Make sure they face you and angle down, like a children's drawing of a Christmas tree.

Threading the Saw Image 2 Hold the blade next to the frame for a visual comparison. The frame should be roughly set so it's slightly taller--about 3/4''--than the total length of the blade.

Threading the Saw Image 3 Insert the top of the blade between the frame and the pad with the teeth facing out and down. Ensure the blade spine is parallel to the back bar of the saw frame, and the very top of the blade is touching the top of the opening at the set screw. Tighten the top set screw to hold the blade firmly. The bottom of the blade should float freely just above the bottom set screw and pad.

Threading the Saw Image 4 Insert the top of the saw frame, with the blade facing up, into the mandrel hole of your bench. Alternatively, position the top bar of the frame against the lip of the bench.

Threading the Saw Image 5 Push slightly against the bottom of the frame handle with your hip, shoulder, or sternum. You will see the bottom bar of the frame move closer to the bottom of the blade. Keep pushing gently until you can capture and insert the blade between the pad and the frame.

Threading the Saw Image 6 Tighten the bottom set screw securely while maintaining pressure on the frame.

Threading the Saw Image 7 Release pressure on the frame slowly.

Threading the Saw Image 8 Verify the blade is tight by ''pinging'' it with your fingertip. It should make a clear, musical sound. If it doesn't, you'll have to adjust the frame to increase pressure on the blade.

Threading the Saw Image 9 With the blade still in position, loosen the frame set screw. Hold the frame in your hand with the back of the frame against the heel of your hand. Pull down on the bottom bar with your fingers to increase tension on the blade. Tighten the frame set screw and test the ping of the blade again. It should be high and clear.

Choosing a Blade

  • The more intricate or curvey the cut, the finer the blade--unless your sheet is very thick.
  • The blade should have a minimum of three teeth contacting the metal when sawing. Too few teeth contacting the metal will result in choppy, jumpy motion. Too many teeth may result in broken blades. To compare, hold the blade spine against the sheet and look at them both from the side to see if the metal is three teeth deep.
  • When you drill a pilot hole for inside piercings, ensure the blade has enough clearance to move freely in the hole.

Practice Makes Perfect

You will cut the entire square of aluminum into tiny shapes and strips by following the pattern in sequence. If you're right-handed, the waste side of the sheet should be to the left, and vice versa. By the time you saw all the lines of the pattern, you'll have learned all of the essential sawing maneuvers. Try to stay on the lines, not to one side or the other. After you've cut the entire square, move on to the next metal square using the same pattern.

Try the 18-gauge copper with the same pattern and a 1/0 blade. After that, try 20-gauge bronze with the 2/0 blade, and finally 24-gauge brass with a 6/0 blade. Note the increase in hardness as you cut the different metals--hopefully, your skills will advance at the same rate of difficulty you'll have sawing them. If not, practice until they do.

Attaching the Pattern to Metal

There are many ways to transfer a design to metal, but I find this method the easiest:

Attaching the Pattern to Metal Image 10 Photocopy the drawing, trim the excess paper, and coat the back of the paper with a thin coat of rubber cement. Let the cement dry.

Attaching the Pattern to Metal Image 11 Brush a thin coat of rubber cement on clean, dry metal and let the cement dry.

Attaching the Pattern to Metal Image 12 Carefully roll the paper onto the metal, pressing the dried cement together so it bonds. Start at one edge and continue across. Be careful not to wrinkle the paper as you roll it onto the sheet.

Making Your First Cut

Thread a 2/0 blade into your frame. Attach the pattern to the 20-gauge aluminum. Position the metal on the bench pin according to whatever your dominant hand is. Take a deep breath and relax your hands and arms. Exhale.

Making Your First Cut Image 13 Hold the saw in your dominant hand. Position the frame at a 45° angle to the sheet, next to line number one. Put your nondominant thumb over the spine of the blade and gently stroke upward to create a score where you intend to cut. Repeat two or three times.

Making Your First Cut Image 14 Position the saw vertically. Hold the frame loosely--you don't need a death grip--lock the wrist and begin to move the saw up and down a small amount until the kerf has been started.

Making Your First Cut Image 15 When you have a good start, begin to saw using the entire length of the blade. Go slowly; do not push forward or down; and do not twist the blade. The saw blade should move freely--like a sewing machine needle.

Making Your First Cut Image 16 Guide the metal by holding it on either side of the blade using the first and middle fingers of your nondominant hand. Steer the metal, not the saw. Slow down when you get to the edge of the sheet, and let the cut metal fall away from the blade.

Making Your First Cut Image 17 Cut the entire length of line number one. Check your work. Continue sawing all of the practice lines in order. Read the special scenarios for inside and outside corners, and save cutting out the hole for last.

If You Break a Blade

Go ahead and get the swearing out of the way. Pick up the broken blade sections to see if any are long enough to reuse. Save what you can, and dispose of the rest--you don't want steel mixed in with your scrap. I keep an envelope in my bench pan just for useable, broken blade sections.

If the blade has snarled in the metal, unscrew one of the frame set screws and try to work the blade loose. If it is hopelessly snarled (extremely rare) and you can't budge it, unscrew all of the set screws, remove the saw frame, and pull the blade out of the kerf with toothed pliers. Throw it out; it will probably be bent or twisted beyond repair.

Thread a new blade and try again, but make sure the sheet hasn't warped, bent, or twisted, and that the kerf is clear and open--or you'll end up killing another blade.

Special Scenarios

Once you've sawn the straight, gently curved and tightly curved lines without breaking a blade, don't get cocky--you'll need to saw the inside and outside corners next. These are the hardest cuts to master, especially in thicker gauges or harder metals. The most important tip for these sawing scenarios is to pivot the metal in place around the blade at the same time you're moving the saw. Remember, the blade does not cut, it chips, so move the saw up and down in short strokes and pivot the corner point of the cutting line around the blade until the teeth are facing the direction you want to saw next. Sharp direction changes are very difficult for everyone, so don't get discouraged.

Cutting Out a Hole

Cutting a hole is easy once you figure out which direction to saw in. You'll want to drill the pilot hole near the cutting line in a position that allows you to transition efficiently and directly into the cutting outline without a sharp change of direction.

If you're sawing a complex pierced or fretwork design, saw the innermost holes first, and then work out toward the exterior of the design--that way, the intact, exterior metal supports the fretwork.

Cutting Out a Hole Image 18 Because I'm right-handed, I want the ''hole'' I'm sawing to be to the left of the blade. If you're left-handed, do the opposite. Make a dot with a marker near the cutting line.

Cutting Out a Hole Image 19 Centerpunch the dot on a steel block, and drill it with a number 54 bit (a good, all-purpose size for most blades).

Cutting Out a Hole Image 20 Unscrew the bottom set screw and string the metal onto the blade with the pattern facing away from you (toward the top of the frame). Slide it all the way up the blade.

Cutting Out a Hole Image 21 Thread the bottom of the blade as usual. Make sure the blade is under tension. Slide the metal down to the bench pin and start sawing toward the cutting line in a gentle curve. Once there, continue to follow the outline. Remove the completed piece from the saw by releasing the bottom set screw and sliding the metal off.


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