Making Right Triangles and Fabric Grainlines
Play Well Together
With just a little practice, you can train yourself to use fabric grainline advantageously and improve your patchwork blocks amazingly! It is especially important to learn and practice cutting right triangles appropriately, as they are the pieces most likely to sabotage your blocks! With careful cutting and awareness of grainline, you can eliminate rippled or stretched edges and sew flat, square, blocks that will make straight rows at quilt assembly time.
Anatomy of a Right Angle TriangleA right angle triangle is a three-sided figure having one 90-degree or square corner. The most common right angle triangle used in patchwork has two equal length legs and is called a "half-square triangle" by quilters and an acute isosceles triangle by mathematicians.
x = Vertical leg
y = Horizontal leg
z = Hypotenuse (longest side of a triangle)
In quilting, right triangles are often made by cutting a square in half diagonally to make 2 right triangles, resulting in having the straight grain on the legs (indicated by arrows).
When squares are cut diagonally twice, you still get right triangles, but the straight grain is on the hypotenuse.
There will be appropriate times for both cuts; it depends on the position of the triangle in the patchwork design. The sooner you learn which grainline is the appropriate grainline for the design you are making, the happier you will be with your finished blocks. Also, we don't recommend cutting squares in halves or into quarters to make triangles, because we have a more grainline friendly way to do it (described in later paragraphs).
Definitions of GrainlineLengthwise grain of fabric identifies the threads that run parallel to the selvage. They are very firm with virtually no stretch or give.
Crosswise grain identifies the threads that go from one selvage to the other. They are quite stretchy and tend to create a small ripple when seamed.
Bias runs diagonally across perpendicular threads and is very stretchy.
True bias runs at a perfect 45-degree angle across perpendicular crosswise and lengthwise threads and is verrry stretchy.
Whenever possible, you want straight grain (either lengthwise or crosswise, but when there is a choice, lengthwise grain) of the fabric on the outside edges of a piece, on the outside edges of a sub-unit, on the outside edges of a block, and if there is a border, on the outside edges of the border.
Having said all of that, design overrides grainline. Showcasing stripes or fussy cutting directional prints overrides grainline preferences. In those cases, cut the pieces as needed and press carefully so the edge won't grow bigger.
Cutting PiecesSquares are fairly easy -- as long as you cut strips on either the crosswise or lengthwise grain, a square cut from that strip will have 2 opposite sides on crosswise grain and the other 2 opposite sides on lengthwise grain.
Rectangles add another dimension. Whenever possible, you want the lengthwise grain of the fabric to be the longest vertical or horizontal dimension of a piece. Cut strips the narrow dimension of the rectangle on the lengthwise grain and then cut pieces as long as the long dimension of the rectangle.
But when you see right triangles, turn on your thought processor! They are frequently the shapes that are cut wrong and will create major problems in the block.
Look at the From Marti Michell templates and you will see that they include grainline arrows. Typically, when that arrow is placed on lengthwise grain of the fabric, it is the ideal cutting position. (This is not true on squares A-3 or B-10, but that is too long a story for right now!) At the top of every Farmer's Wife conversion chart, we identify any piece where the appropriate grainline for the block overrides the silk screened arrow on the template.
Playing Well With NancyNancy is a perfect block for analyzing triangles, because for best results some of the A-6 triangles in this block should be cut with the legs on straight grain and some with the hypotenuse on straight grain. (NOTE: Specific cutting instructions for this block are on the PDF Template Conversion Chart, and the block also includes rectangles and a square.)
To follow the guideline that you want straight grain on the outside edges of the block, the triangles for the corners of the block should be cut with legs on straight grain from strips cut on the lengthwise grain.
Yet in the Flying Geese sub-unit, to follow the guideline that you want straight grain on the outside of the sub-unit, the small triangles should be cut with the legs on straight grain (as shown above), and the large triangle should be cut with the hypotenuse on straight grain.
If you cut a square into quarters to yield 4 triangles with straight grain on the hypotenuse, 2 of the triangles will have the hypotenuse on the taut lengthwise straight grain and the other 2 will have the hypotenuse on the stretchier crosswise grain. Your blocks will be more accurate and square when all 4 triangles are cut so the hypotenuse is on the lengthwise grain. (Cutting template 6 with the hypotenuse on the straight grain is an example of a grainline override.)
To follow the guideline that the outside edges of the block should be on the straight grain, the largest triangles in the Nancy block should also be cut with the straight grain on the hypotenuse. (NOTE: Only one section of Nancy is shown below.)
Carefully follow the PDF instructions for cutting the pieces from strips and, like the Rambler block diagram shown earlier, Nancy will have straight grain on all edges -- lengthwise grain on 8 of the 12 edges and crosswise grain on the other 4.
My Nancy BlockClick on the photo to see a larger image.
Click the link to download the Template Conversion Chart for this block:
for Block #76 Nancy
Visit these other Farmer's Wife Sew Along blogs, too, for sewing tutorials and other info about the these blocks:
8-1/2 inch Nancy for the Mystery SamplerThis is going to be an absolutely wonderful block for the 8-1/2 inch Blocks Mystery Sampler. I haven't decided on the fabrics for my 8-1/2 inch blocks, so while I ponder my fabric choice, I am trying to provide a little research on the blocks we will be using in the mystery sampler.
Block #2900 in Barbara Brackman's Encyclopedia of Pieced Quilts, credited to "Hearth and Home", is called Aunt Nancy's Favorite. It is the same as Nancy in the Farmer's Wife 1930s Sampler Quilt, Nancy. Observe grainline overrides with both A-2 on the main fabric and A-4 on the accent fabric.
To benefit future historians, we try to identify public domain blocks by known names when we use them in our books and patterns, but when we modify a traditional block and give it a new name, which we have done with some blocks in our Encyclopedia of Patchwork Blocks Volumes 1-4, we put the new name in italics to identify that this is our name and, in fact, we think it to be a unique block pattern.
Cutting the 8-1/2 inch Nancy Block
Main Fabric1. From strips as wide as A-5 (2 inches cut) and approximately 13 inches long, cut 8 A-6 triangles for small triangles in Flying Geese units.
2. Cut 2 strips as wide as A-3 and approximately 13" long, and cut 4 each A-4 and A-2, as shown:
3.Cut one A-1 square.
Accent Fabric1. Cut 2 strips as wide as A-5 (2 inches) and approximately 14 inches long.
2. Stack and cut 4 modified #1 rectangles and 4 #4 triangles.
Assemble the block as shown in the Farmer's Wife 1930s Sampler book.