Friday, February 24, 2012

Quarter square triangle method

What follows are the directions for quick piecing this quilt top, which measures approximately 41 x 50 inches. Our church, together with a local quilt guild, makes about 200 quilts of this size every year for cancer patients and others who are going through hard times and who may be comforted by a handmade quilt.

This quilt top was made by creating half-square triangle blocks with edges along the bias, forming these squares into pinwheels, turning the pinwheels on point so that the grain of the fabric is horizontal and vertical, and filling in the edges with half pinwheels (and the corners with quarter pinwheels).

Note: these directions are for creating a scrappy looking quilt. It could easily be made with pinwheels that are each made from two fabrics. Then the pinwheels would stand out on their own and be noticeable as pinwheels.

Step 1: Fabric selection

Choose 24 dark and 24 light six inch fabric squares. I had 24 deep red, magenta, reddish brown and multicolored six inch blocks on hand. I decided to use up some of my pale orange fabric for the light squares. The more different fabrics you have, the scrappier the quilt will be.
Set aside four each of the light and dark squares. They will be used to fill in the edges. I set aside fabrics that didn't stand out as much because I didn't want the design to be more interesting along the edges than on the inside.

If you are making two-colored pinwheels, two of the fabrics that are set aside should match two of the 20 fabrics that are used in the next step.
Pair up the remaining 20 squares, avoiding duplicate pairs as much as possible for the scrappy look.

Step 2: Create the pinwheel blocks.

In this step you can optionally align the fabric so that the patterns have a consistent orientation throughout the quilt. This is not really a crucial step, but in this example, one of the patterns had an obvious orientation that I wanted to preserve. The way I do this is by lining up the six inch squares so that they have the same direction relative to the fabric on the bolt. This direction is easily determined by stretching the fabric slightly. In the direction that the fabric is wound around the bolt, the fabric doesn't stretch at all. In the direction across the fabric, from selvedge to selvedge, it stretches slightly. So I made sure each square stretched from left to right and sewed them together that way.

For this quilt it is not actually necessary to use a 1/4 inch presser foot. However the same seam allowance must be used throughout, otherwise the quilt will be skewed.

Sew the squares together all around the side edges. I found it easiest to turn the corner with the needle raised on the sewing machine. Notice that the squares have the corners trimmed. This too is optional, but it will remove the points that occur when the resulting squares are pressed open.
If you don't mind protruding points at the ends of the seams (as shown in this picture), you can skip trimming the corners. I prefer to trim the corners as soon as possible at the sewing machine rather than waiting to trim them on the ironing board before pressing them open.
Cut each square through both diagonals, using a transparent flat plastic ruler and a rotary cutter. Be EXTREMELY careful and cut precisely. If you're not used to using a rotary cutter, take your time. Close the rotary cutter immediately after making the second cut.
Optional: keep the triangles in separate piles according to their original configuration. This makes it easier to achieve an even scrappy look and makes the pinwheel assembly more efficient.
Press the squares open, keeping them in their own piles if opting to preserve the orientation. Press all seams towards the dark fabric. When we join these squares, we will align them by interlocking the seams. This is very important for achieving a smooth, flat quilt with seams and points that line up precisely.
Arrange 18 pinwheels on your design wall, or if you don't have one, use your design floor like I do, or a table. If using the optional orientation method, each pinwheel quarter will come from a separate pile of half-square triangles. There will be eight squares left over. These will be used to fill in the edges.
If you are making uniform pinwheels with two colors each, these eight squares should match two of the squares that were set aside at the beginning.

Sew the left and right squares of the top and bottom of each pinwheel together. I sewed these squares all at once, making a long chain of half pinwheels. If you use this technique, take care to keep the top and bottom of each pinwheel together. Press all seams towards the dark fabric.

Next sew the top and bottom halves of the pinwheels together. Press the seam loosely in any direction, or not at all. During the assembly of the top, these seams will lie in alternate directions, and it's not possible to predict at this step which way they will eventually go.

Step 3: Arrange the pinwheels and fill in the edges with squares and triangles.

Arrange the pinwheels on point in alternating rows of three and two. Take care to have them all point in the same direction. In this picture the pinwheels are rotated 1/8 turn clockwise so that the left top square is pointing up and the right top square is pointing to the right side. This means the seam joining the top and bottom of each pinwheel is on the downward diagonal. We are going to sew the rows together in this direction, so that we can orient the center seam of each pinwheel in either direction as necessary.


In the picture on the left, I placed the pinwheels from left to right without worrying how they looked together. In the second picture, I have rearranged them so that the different patterns of fabric are more evenly distributed throughout the quilt. This step is much easier if the original six inch squares are all different.

Next fill in the side gaps with the eight remaining squares. There will be two empty gaps that we will fill in the next step. If we had made an extra set of half square triangles, there would be two that we could not use unless we picked them apart.
Cut the eight reserved six inch squares along each diagonal, creating 32 small triangles. Fill in the two gaps with two triangles each, and sew them together. Finally fill in all of the edges and the four corners with the rest of the triangles. At this point it's not so important to maintain the orientation of the fabric, but I do anyway in order to keep the different patterns distributed evenly. In this picture I have rearranged the pinwheels so that every row and column contains a bit of the green and orange print.

If you are creating uniform pinwheels with two colors each, assign the matching triangles to the side squares of the same colors. Fill in the side gaps with a third light and dark color, and fill in the corners with the remaining light and dark color.

Next sew the corner triangles together and sew the small triangles to either side of the gap-filling squares. I tried to continue to press the seam towards the dark fabric, but if the last triangle added is a light color, it makes more sense to press the triangle away from the square, which has the seam going towards the light color.
Step 4: Assemble the top

We are going to sew diagonal rows of pinwheel blocks and then sew the rows together. With some care we can make sure that all the matching seams interlock as we join the edges. In order to do this as painlessly as possible, we will attach one block per row starting with the right side half pinwheel blocks, the lower right corner, and the lower half pinwheel blocks. Each of these will be attached to the adjacent block, and all the seams will be pressed in the same direction (in this case, to the right). These seams will eventually be matched with the seams created in the next step, which will all be pressed in the other direction.

The seam along the center of the whole pinwheel block must be adjusted to go in the opposite direction as the matching seam on the half pinwheel block. This may cause the seam on the whole pinwheel block to not lie flat.
Before the seam is pressed open, press this wavy seam to the side. Then flatten the block after pressing the joining seam open.

Keeping careful track of the order of the rows, add the next pinwheel block to each diagonal row. Press all the seams the other way. In this picture I have pressed the second seam to the left. By doing this, the seams will be facing opposite directions when the rows are joined.

Continue until all blocks are joined into rows. Press seams in alternating directions throughout each row.

Join the rows and press the seams in either direction. Take care to use the exact same seam allowance as in the previous steps. Otherwise the top will be skewed.

Cut four six and a half inch wide border panels from selvedge to selvedge of border fabric. Sew the side panels first, then sew the top and bottom.

1 comment:

  1. Cool way to make these! Thanks for the tutorial,

    ReplyDelete