Creative Woodworks & crafts 2004-09, страница 18

Going Around In Circles?

- — by Karen Boelman

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Like driving a car

One of my greatest cha lenges in scroll sawing has been learning how to cut a nice, smooth circle. Tn fact. I would say it's just about impossible to cut a "perfect circle." unless your brain is equipped with laser cutting technology. Mine isn't, but on a good day I can cut a pretty decent circle. So, I'd like to share a few tips that work for me, and suggest a few tilings for you to think about in order to help you improve your circle cutting skills.

To get you thinking in the right direction... 1 compare

cutting a circle to going around a corner in a car. Whether you're driving a car, a semi, a bicycle or a piece of wood, it's all the same skill. You have to learn to co-ordinate your speed and the turn rate of the wheels (or wood) in order to make a smooth turn. Our 16-year-old son, Jamie, has just gotten his driver's license, and the first few weeks of watching him learn how to go around comers was interesting! Sometimes we bounced over the curb and sometimes we were over in the wrong lane of traffic, but eventually he got the hang of it. He learned to match his speed and turn rale so that he could get around the corner smoothly and accurately.

Just like the cornering speed in a car, you can find your own comfortable cornering speed on your saw that allows you to steer smoothly. Hie more times you slow down or speed up or make corrections in your steering, the bumpier your turn and circle may be. So. the goal is to keep everything going at a smooth and steady rate. Also, you need to pay attention to what you're doing while you're sawing a circle. You should try to look at the line ahead of you and anticipate how you will have to maneuver the wood to keep the blade cutting where it's supposed to cut. Pretty soon it becomes second nature, just like driving a car or riding a bike. However, you still want to pay attention to what you're doing; otherwise your car could end up in the ditch or your project could end up in the scrap box!

Tips that work for me

When I cut circles, I usually "steer" the wood with one hand and use one or two fingers from my other hand to hold down the wood and act together as a pivot point (see Fig. 1). I also pay attention to where 1 put my steering hand on the wood. The object is to change the position of my steering hand as little as possible as cut around the circle because each time I slow down or stop lo move my hand, I may leave a blemish on my finished project. Most of the time I don't have to come to a complete stop to change hand positions. I just keep the wood moving slowly with my hold-down hand, and when my steering hand is in place it becomes the dominate moving force again (sec Fig. 2).

There are times, however, when 1 do have to come to a complete stop to change hand positions. When this happens, it can be hard to pick up where 1 left off—that is, to get the feel of the curve back. So, here's what 1 do: 1 back up the blade 2" to 3" into the kerf (the cut line where I've already sawn). Then, as I follow along in the line I've already cut, 1 can get reacquainted with the feel of the curve before my blade actually starts cutting into the wood again.

As you cut circles, there are bound to be instances when things don't go just right, in these cases, you should always try-to figure out why things went wrong and what you could have done differently to make things go better. For example: if you find yourself cutting wide on a curve (cutting to the outside of the pattern line), then your saw may be cutting faster than you arc turning (see Fig. 3). So, you need to either slow down your feed rate (the speed at which you're pushing the wood through the blade) or turn faster. When you cut a corner short (cutting to the inside of the pattern line), you are probably turning faster than your saw is cutting (see Fig. 4). Increasing your feed rate or turning slower should help.

If your finished circle is bumpy, wavy or just not smooth,

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