Draw and Print a Circle

The circumvolve is, in my humble opinion, the Queen of the geometric shapes. Don't get me wrong; I similar all those squares, rectangles, triangles, octagons, and whatnot; but the circle is the coolest of the bunch: polish and pretty and endlessly useful. However, trying to draw a perfect circle without a pattern is a claiming, and figuring out the proper size of an opening into which a circumvolve can be inserted requires working with Pi (or π), which is not the succulent kind you can eat with a scrap of ice cream. We're hither today to help you with the steps you've forgotten since high school geometry class (or maybe never learned because you were too decorated passing notes with Susan Ellery!). We'll prove y'all the parts of a circle, how wide to cut fabric to fit a circle, and how to draw a circumvolve without a design. We've as well included a handy conversion from decimals to inches, which is necessary when working with Pi.

The parts of a circumvolve

Let's commencement with remembering what all the parts of a circumvolve are called and how Pi (π) fits into the mix.

Radius: the altitude from the center of the circle to the outside edge

Diameter: the altitude across a circle through its centre signal

Circumference: the distance around the outer edge of a circle

π or Pi: the proper noun given to the ratio of a circle's circumference to its bore, expressed every bit the decimal iii.fourteen

How broad to cut fabric to fit a circumvolve

If y'all know the diameter of your circumvolve, y'all can use a standard formula to effigy out the width of the fabric cut needed to make a tube. That width is the circumference of the circle that will exist inserted into the tube (we have a cracking pace-past-step tutorial on how to insert a circumvolve into a tube).

The formula: iii.14 (π) x diameter = circumference

Case: You want a finished 12″ diameter base (a 12″ diameter circle) in a duffle bag.

3.14 10 12 inches = 37.68 inches

(This works with the metric system too: 3.fourteen x 30 cm = 94.2 cm)

An important step many people miss at this bespeak is forgetting to add extra (to both pieces) for the seam assart. If you use a standard ½" seam allowance, yous demand to add 1″ to the diameter of your circle ( the diameter increases by double the seam allowance)and 1″ to the width of your fabric (½" for both sides of the seam assart). In our instance, that means:

The circle should start as thirteen″ in diameter.

The textile should be 38.68″ in width

The acme of your fabric cut is variable and dependent on your project. For example, a alpine duffle bag might exist thirty″ in height whereas a shorter saucepan might be only 10″.

Converting a Decimal to a U.s.a. Ruler Measurement

If you are using Pi, recollect it always returns a decimal number. If you lot already deal with the metric system, y'all rock –  no conversion necessary.

For those of us in the world of inches, you need to find a yardage conversion.

In our example we have 38.68 inches. Harumph! The table beneath will give you a close-enough ruler match.

The decimal .68 is closest to .63 or ⅝". We tin utilize 38⅝" as the width of the textile piece y'all are cutting for your tube.

How to Draw a Circle

If yous have a supply of large compasses, yous're in luck, and can easily describe yourself all sizes of circles. But you can also easily brand your own compass to draw a circle.

To showtime, yous need to know how big y'all want your circle (the bore). For our ongoing example, nosotros want a xiii″ diameter circle

To draw a circle you need to know its radius. Every bit you learned to a higher place in the showtime section, the radius is ane half of the diameter. In our instance, ane half of 13″ is vi½".

The full circle method

1. Use a sheet of lightweight paper (graph or pattern paper works well) that is at least 1″ larger all around than the circle you want to depict.
2. Cut a piece of string nearly 4″ – 5″ longer than your radius. Nosotros used a 10″ length of string.
3. Tie 1 end of the string to a brusk pencil.
4. Identify the betoken of the pencil toward the outer border of the paper with enough room from the border to brand a full sweep.
5. Measure from where the point of the pencil touches the newspaper backwards past the length of the radius (in this case 6½").
6. Pin direct through the string into the paper at that exact point.
7. Keeping the string taut, draw a perfect circle using your bootleg compass.

The folded quarters method

1. Once again, offset with a foursquare of lightweight newspaper at least 1″ larger than the circle you desire to draw.
2. Fold the newspaper into quarters. Make sure your original square is even and truthful! Position the newspaper with its folded edges forth the bottom and left side and the open edges along the top and right side.
3. Identify a see-through ruler at the exact center of the bottom left corner of your folded foursquare. Swing the ruler from the height to the bottom of the foursquare, similar a pendulum or compass, measuring and marking a dot at the 6½" point in iii to four spots. Yous are creating a semi-circle arc. Brand sure the end of the ruler at the corner point doesn't shift position.
   
4. Cut along the arc through all the layers and unfold the finished 13″ circle. You can now use this paper pattern to cut your fabric circle.

With your spiffy new circle, you tin can now sew the side seam in the main material cut. Then pivot the base to the resulting tube and sew the tube to the circle using a ½" seam allowance. The result is a 12″ diameter finished base.

As mentioned above, for more on this technique, encounter our tutorial: How to Insert a Flat Circle Into a Tube.

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Source: https://sew4home.com/draw-and-measure-a-circle-without-a-pattern/