Pinwheel Quilt Block Tutorial

Pinwheel Quilt Block Tutorial

Pinwheel blocks are a fun way to add some pizazz to your quilting creations. They can be used as an accent block amid other block types, or they can be used for an entire quilt, as they are in my quilt pattern Pinwheel Parade. This tutorial will walk you through the steps to making a Pinwheel block.

Half Square Triangles

Pinwheel blocks are made up of four half square triangles (HST). There are many methods to make HST's, but for the purposes of this tutorial we will focus on the two-at-a-time method. For a more in depth tutorial on HST's, please see my tutorial How to Easily Make Half Square Triangles - Three Simple Methods.

We will be making an 8" finished Pinwheel block. For this, you will need four 4.5" finished (after trimming) HST's. 

You will need 2 - 5" focus fabric squares and 2 - 5" background fabric squares.

Place a 5" background square on top of a 5" focus fabric square, right sides together. Using a ruler and pencil, draw a diagonal line across the top (background) square. It is helpful to use a dab of fabric glue at the corners or pins to hold the squares together while you mark. 

Half Square Triangles Draw a Diagonal Line

Sew a line ¼" on each side of the drawn center line. Press the blocks flat, this serves to set in the seam lines, helping them to lay flat when you press them open.

Half Square Triangles sew on both sides of the diagonal line

Cut along the center diagonal line, making two triangles. 

Half Square Triangles cut on the diagonal line

Press open the triangles, pressing the seam toward the darker fabric. Use care not to stretch the bias edges. 

Half Square Triangles Pressing Open

Use a square ruler to trim the block to 4½" square.

Trimming half square triangles

Completing the Block

Lay out your block as shown below. 

Lay out the half square triangles for the pinwheel block

Sew the top two blocks together. Then sew the bottom two blocks together. Press the seams in alternating directions. 

Sew the half square triangles together to make the Pinwheel block

Sew the top and bottom sections together to complete the Pinwheel block.

Completed Pinwheel Block


Pressing Pinwheel Blocks

After the top and bottom sections are sewn together, there will be a lot of bulk in the center where all the HST’s meet. This is not ideal for many reasons! This bulk may distort the blocks, altering the appearance of the blocks. It may cause thread breakage when you try to quilt through the block as well. To remedy this, press this last joining seam (where you have sewn the top and bottom sections together) in alternating directions. (On one side of the center, the seam would be pressed up, on the other side of the center, the seam would be pressed down.) As you do this, use a stiletto or your finger to carefully pull the edge of the center joined seams away from each other, like fanning them out. 

Pressing a Pinwheel quilt block

This will create a little mini-pinwheel at the center intersection point as shown below. Press the block well from both sides and your Pinwheel block will lay flat. 

Close up of the back of a Pinwheel quilt block after pressing

Pinwheel blocks lend themselves to scrap fabrics very well, making them an excellent scrap-buster project. They can be elegant or casual, depending on the fabric and block setting used. They are also a good way to use up any left over HST's you have lying around from other projects!

I hope you have found this tutorial helpful!

Happy Quilting!

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