Making Perfect Pinwheels

Would you like to machine stitch some Pinwheel blocks but can’t seem to get all of those triangle points to come together very well?


Since I’m making a dozen of these blocks for the Dinotyke quilt, I thought I’d share some photos and a few tips to help you stitch perfect Pinwheels.

The Pinwheel block like the ones shown above are made from 2 different fabrics, using 4 half-square triangles of each fabric. To make a half-square triangle, cut a square, then bisect-cut from one corner to the opposite corner. I cut my squares on the straight-grain which places the bias on the long side of the triangles.

Sew 4 squares of half-square triangles. Chain sew each pair of triangles together at the longest-side, taking care that you sew slowly and cautiously because you are probably sewing across the bias portion of the triangles and want no distortion.

As you finish stitching your first set of triangles, begin feeding your second set of triangles so that your needle and feed dog on the sewing machine do not garble up the tips of the triangle. I try to raise and lower my presser foot slightly when I begin each new triangle to release a bit of the presser foot’s weight.


Once you have made your four squares from the sets of triangles, it’s time to press the squares with an iron. One square at a time with wrong side up, gently open the seam with your fingertips and press the square with the seam open, just like you see in the photo below. Press all of your squares in this manner:


Return to your sewing station, then arrange the four squares to resemble the Pinwheel block. Such a cute little block, isn’t it???


Working with 2 of the squares in the correct placement like this,

pin5flip one of the squares to the other square so that right sides are facing one another like this:

pin6Now you are ready to align the two squares together!

Before you place your first pin in the blocks, check to see if the seams are aligned properly. The first point-of-concern will be the corner where you have a seam running through it. To piece a perfect Pinwheel, it is critical that your seams line up correctly each time you stitch.

At the corner, turn back the top square and make sure the seams from both of the squares are lining up correctly. If you had pressed the seams to one side, these would lock-in-place, but with open seams, you must match the seam line differently. In my photo, you can see that my hemostat is holding the top square back (that way I can take a photo). See how the seams have aligned on this corner?

pin7Now that the squares are lined up, carefully pin the 2 layers of fabric together in the corner. For the photos, I had to do this on the cutting matt, you will probably do this by holding your squares in your hands.

pin8Now that the corner is pinned, do the same thing in the opposite corner. To make a perfect Pinwheel, you must align the triangular sections very carefully. You need to check alignment of the seam at the opposite corner, so fold back the top square and check your seam to see if both seams are matching. Mine is!

pin9With the seam line running true for both blocks, you can pin the upper left corner now. Disregard any misalignment of the raw fabric edges….that is not as important as the seam lines for this block.

pin10Now it’s time to stitch from the one corner to the other, using a scant 1/4-inch seam allowance.

Repeat the above steps for the other two squares, then you will have 2 pairs like these!

pin11Now that both halves of the Pinwheel are stitched, it’s time to press the center seam of each half open like this:

pin12Now let’s make a perfect Pinwheel!

Double check the block layout before pinning, then flip one half over to the other, right sides together. Since the seams are pressed open, it is not easy to see whether the triangle-points and seams are aligning.


With right sides together you need to check our block-unit alignment before pinning the units together.

Fold back the top block-unit (the one with the wrong side facing up) which is half of the Pinwheel block. This time, check the alignment of the seam AND check to see if the triangle-points meet. Checking the alignment will be similar to before, folding the top portion back:

pin14When you are satisfied with your alignment, pin the blocks together. I pin across the seams and very close to the scant 1/4-inch seam allowance.

Once you have pinned your block at the seam, double-check to make sure that you have aligned your block correctly. The seams should match and the triangle tips should all meet at the intersection. Eight pieces of fabric are coming-together here, so check carefully!

pin15Can you see that the edge on the left side of the block-unit does not line up with the bottom section of the block-unit? No problem….We are more concerned with the triangle-points and the seams aligning, not the raw edges.

Now align the other seam lines for each half. The lines to match-up to make a perfect Pinwheel are the seams for each of the half-square triangle blocks. As before, align the seam for each section, fold back the upper block section and check your placement like this:

pin16When you are satisfied with your alignment, pin that corner where your seam line will be. Repeat for the other side of the block unit. Flip the fully pinned block over to double-check your pinning and stitch your perfect Pinwheel!

pin18Extra tips:

Silk pins are longer and thinner, they produce better results when sewing patchwork by hand or by machine.

Press seams open to reduce the layers of fabric that converge where the triangle-points meet. Press the seams flat, do not “iron” or move the iron.

Trim dog-ears to reduce fabric bulk.

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3 Responses to “Making Perfect Pinwheels”

  1. Violette Says:

    I always press the seams to one side. Do you think that reduces the chance that the seams will align properly when sewing the rows together?

  2. Gene Says:

    Thanks, I used this info to match a project I am working on. I guess that I will have to start pinning things. I dislike having to pin, but it does make it work out better.

  3. Gayle Says:

    Thank you for a great tutorial. :-)

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