How to Draft a Quilt Block
Drafting Supply Checklist
- 1⁄8"-grid graph paper (8 squares to the inch allows the greatest flexibility.)
- Plain paper
- Ruler
- Pencil (mechanical pencils help maintain uniform line width)
- Colored pencils
Reproducing a Block Design
If you're trying to re-create a block from an antique or heirloom quilt, identifying the block and grid can sometimes be difficult, especially with complex quilt tops. It is common for block designers to start with a base grid, such as the Nine-Patch, and further divide the patches into grids (see more detailed information about the Grid Method below). For instance, the Double Nine-Patch block is based on the 3×3 Nine-Patch grid, but some of the squares have been divided into even smaller Nine-Patch units.
To determine the units necessary to reproduce a favorite quilt block, follow these steps:
1. Isolate the block on the quilt.
2. Visualize a grid superimposed over the block. Look for a repeating pattern across the block and count the number of times the pattern repeats.
3. Measure the block to determine the finished size.
4. Using graph paper, a ruler, and a pencil, draw out the block. Remember that the pieces you are drawing are finished size. Once the drafted block is complete, you need to add a 1⁄4" seam allowance to all the edges of each individual piece before cutting.
Original block design: Use the grid system to organize an original block design and to make it easier to figure out cutting and piecing. To practice, draw several miniature grids on graph paper and photocopy them. Draw lines throughout the grid to experiment with new block designs. Think about some of the basic units (triangle-squares, four-patch units, Flying Geese units) and draw them in the grid squares. Keep doodle pads of grids available so you can design when inspiration strikes.
TIP: What size should my finished block be? The finished size of a block is likely determined by the pattern being used. When designing an original quilt or modifying an existing pattern, you can adjust the blocks to a specific finished size. Do keep in mind the grid for the block you've chosen when deciding on a finished size. For example, it is easier to cut the pieces for a 9" Nine-Patch block than it is to cut pieces for a 10" Nine-Patch block.
Computer programs: A variety of computer programs are available for designing blocks and quilt tops. On a computer you can explore multiple block options quickly and without drafting-a timesaver if you're doing a great deal of original design work. The programs allow flexibility in creating thousands of designs, adding color, and seeing how blocks will work together.
Advanced block design: Blocks designed with tight curves and unusual shapes may not work on the grid system. These designs can be executed with different techniques, such as appliqué or foundation piecing. Some blocks require multiple methods.
Test fabric choices: Finalize block design and fabric selections by mocking up a block. Cut the fabric pieces to the finished size (leave off the seam allowances for this test only; these pieces will not be used in the finished project) and sketch the grid and block design on paper. Glue the fabric pieces in position on the paper to create a mock block. Place the mock block several feet away to view the design and color combination. If desired, make additional blocks to test alternate fabric choices. To further test the color and layout, make color photocopies of the mock block. Use the copies to begin planning the quilt top, watching for secondary patterns to emerge and checking color placement in adjacent blocks.
TROUBLESHOOTING TIP: Are photocopies of block patterns accurate for piecing? Photocopiers can distort images. Before using any photocopies as templates for piecing, make a test copy of the block at 100%. Measure the original and photocopy to ensure they're exactly the same size. To ensure consistent reproduction quality, use the same copier when making additional photocopies. See below for the specific enlargement and reduction percentages.
Understanding the Grid Method
Many blocks are based on a grid or can be broken down into one. Working with a grid organizes a design and makes cutting and piecing sequences easier to determine. Some grids commonly used for quiltmaking follow.
TIP: How many grids should I have in my block design? Each division within a grid square means additional piecing. As the number of squares increases, consider the overall size of the block to avoid piecing tiny bits of fabric. For example, a 12" block with 64 squares (8x8 grid) would have 1-1⁄2" squares.
2×2 Grid: A grid of four undivided or divided squares-a Four-Patch or 2×2 squares-offers multiple design options.
Example (see picture): Four three-triangle units on a grid of 2×2 squares form a Windmill block. Triangle-square units placed on a subdivided grid form a Broken Dishes block. Squares and triangle-square units on a subdivided grid form a block called Northumberland Star.
3×3 Grid: A common block/unit in quiltmaking is the Nine-Patch. The Nine-Patch grid, like the Four-Patch, can vary in the number of squares it uses. In the case of a Nine-Patch, the number needs to be divisible by three.
Example (see picture): Squares and triangle-square units compose a Friendship Star block on a grid of 3×3 squares. Jacob's Ladder blocks can form many different patterns when placed together in subdivided squares. (Though based on the Nine-Patch grid, this block incorporates Four-Patch units.)
5×5 Grid: Five squares along each edge give this block design versatility and a center point.
Example (see picture): Triangle-squares and squares form a basket shape to make a Cake Stand block. The same pieces in a different layout create a Checkered Star block. The New Mexico block, a variation on the Checkered Star, is formed with four Nine-Patch units and four three-bar units replacing the squares in the center.
7×7 Grid: With 49 separate patches in this grid, intricate designs are possible.
Example (see picture): Sashing separates the four Bear's Paw units in this Bear's Paw block. Triangle-squares and squares combine to form a Tree of Paradise block. The design of a question block radiates from the center.
Center Points
When selecting a grid for a block design, consider this. Even-numbered grids allow for symmetrical designs. Odd-numbered grids can be oriented around a center unit.
Example (see picture): In a Four-Patch grid, the corners of the units meet at the block center. Four pieced units combine to make a sawtooth and star block.
Example (see picture): A Nine-Patch grid has a unit as its center point. The Ohio Star block is based on a Nine-Patch grid with the center of the star as its focal point.
Adjusting Block Size
You can see how a block you wish to enlarge or reduce will look by using a photocopier. The equations for determining the percentages shown below. You need to know the original block size and the new block size before using the copier. Note: Only adjustments with whole number percentages have been listed.
Enlarge: (New Block Size ÷ Original Block Size) × 100 = Percent Enlargement
Reduce: (New Block Size ÷ Original Block Size) × 100 = Percent Reduction
Original Size Block (finished): 2"
- 150% enlargement = 3" finished block
- 200% enlargement = 4" finished block
- 250% enlargement = 5" finished block
- 300% enlargement = 6" finished block
- 350% enlargement = 7" finished block
- 400% enlargement = 8" finished block
- 450% enlargement = 9" finished block
- 500% enlargement = 10" finished block
Original Size Block (finished): 3"
- 200% enlargement = 6" finished block
- 300% enlargement = 9" finished block
Original Size Block (finished): 4"
- 50% enlargement = 2" finished block
- 75% enlargement = 3" finished block
- 125% enlargement = 5" finished block
- 150% enlargement = 6" finished block
- 175% enlargement = 7" finished block
- 200% enlargement = 8" finished block
- 225% enlargement = 9" finished block
- 250% enlargement = 10" finished block
Original Size Block (finished): 5"
- 40% enlargement = 2" finished block
- 60% enlargement = 3" finished block
- 80% enlargement = 4" finished block
- 120% enlargement = 6" finished block
- 140% enlargement = 7" finished block
- 160% enlargement = 8" finished block
- 180% enlargement = 9" finished block
- 200% enlargement = 10" finished block
Original Size Block (finished): 6"
- 50% enlargement = 3" finished block
- 150% enlargement = 9" finished block
Original Size Block (finished): 8"
- 25% enlargement = 2" finished block
- 50% enlargement = 4" finished block
- 75% enlargement = 6" finished block
- 125% enlargement = 10" finished block
Original Size Block (finished): 10"
- 20% enlargement = 2" finished block
- 30% enlargement = 3" finished block
- 40% enlargement = 4" finished block
- 50% enlargement = 5" finished block
- 60% enlargement = 6" finished block
- 70% enlargement = 7" finished block
- 80% enlargement = 8" finished block
- 90% enlargement = 9" finished block
Figuring Proportion for Blocks That Are Not Square
To figure dimensions on blocks that are not square, use these formulas.
Height Formula
If the desired width is known, use this formula to determine the block height:
- Desired Width ÷ Original Width = A (proportion factor)
- Original Height × A (proportion factor) = New Height
Example: If the original block is 5" high by 6" wide and you want it to be 12" wide, divide 12 by 6 to get 2 (proportion factor). Multiply the original height of 5" by 2 (proportion factor) to determine that the new finished height of the block is 10".
Width Formula
If the desired height is known, use this formula to determine the block width:
- Desired Height ÷ Original Height = B (proportion factor)
- Original Width × B (proportion factor) = New Width
Example: If the original block is 3" high by 7" wide and you want it to be 4-1⁄2" high, divide 4-1⁄2 by 3 to get 1-1⁄2 (proportion factor). Multiply the original width of 7" by 1-1⁄2 (proportion factor) to determine that the new finished width of the block is 10-1⁄2".