Windmill – Pinwheel tutorial -Post 2

Pinwheel Block

In  a previous post gave the fabric requirements for my block.

So you have all your fabric together. Cut out and stacked. Now we see how to sew the basic units for the block.

How to put the block together will be in Post 3!

Step 1 The Double Coloured Half Square Triangle

Construction of the secondary Blade –

  • With a pencil mark a diagonal line on the wrong side of each of the white squares.

Tips – Put a fine emery sheet / sand paper below the fabric when drawing the line

  • Take each white square and layer it on top of a red square, right sides facing.
  • Sew each pair together with two seams, stitching ¼” on either side of the drawn diagonal line. I find it is better to be just a thread or two less than ¼”!

  • Cut across the diagonal line in the centre to make 8 units.

  • Press the seam (of the unopened unit ) to set it. A trick I have learnt is to keep the dark side on top when pressing the unit. Then when you flip it open, the seam is on the dark side!

  • Press the seam (to the dark side) – you have 8 (diagonally) red and white `triangle squares’


  •  Now comes a very important step – squaring the unit. Place the 45 degree angle on the diagonal, and trim down the square to 5″.

(Theoretically, you could have started with a square about 5.25″ but I have learnt it is better to stitch a bigger unit, and trim it down to size)

At the end of Step One, you shall have two sets of 5″inch squares, red and white.

Step 2 The Basic Unit

  • I marked a diagonal on each of the eight blue squares by lightly finger pressing it, as a pencil mark would not show in it. I needed to be very careful not to stretch the fabric across the bias while doing this!

  • The next step was to pair the eight 5″ blue squares with the red and white triangle squares. One needs to be very careful that the diagonal on the blue square is perpendicular to the seam of the red and white TS

  • Sew each pair together with two seams (slightly less than) ¼” from the diagonal.
  • Before cutting across the diagonal, check your triangle square below again!
  • Once satisfied, cut to get 16 squares. Set seam with blue side on top and press open, seam on blue side!
  • Our basic unit is ready , except for the tedious part – trimming it down to 4″. So go get yourself a cup of coffee or check your facebook page before you settle down to the next step, where it really is very important to be accurate!

End of Step Two you have – 16 units:

  • Again… back to your ruler, the 45 degree line …this time, you have an additional 45deg line to crosscheck L …Now you will understand why I suggested you begin at 5″ and trim down to 4″!
  • You need another break after your 4″ units are ready to your satisfaction all angles 45 and 90 degrees and all corners perfect!

In the next post, we shall be putting together these units into pinwheel blocks.

Author: Mads

In alphabetical order: daughter, mother, painter, philosopher, poet, quilter, seeker, wife...

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