How to make Three-Piece Square Triangles for the Milky Way Quilt

For the Milky Way Quilt, you will need to make four (4) Three-Piece Square Triangles. Don’t worry - they’re much easier to create than you might think! I’ll show you how to make them.

 

Check out the Instagram reel for a quick video. (click HERE)

 

First, follow the instructions in Step 1 to make two (2) Half-Square Triangles (HST).

Trim the HSTs to 4 1/8" squares, if necessary.

 

On the wrong side of Square B, draw a diagonal line from corner to corner.

 

Right Sides Together (RST), layer Square B onto an HST and secure it with pins.

Note: Carefully refer to the photos above and ensure that the marked diagonal line on Square B runs in the opposite direction to the stitched line on the HST.

 

 

 Sew two seams, each 1/4" away from the marked line, cut on the marked line.

  

Flip the Three-Piece Square Triangle and trim to 3 1/2" square. Refer to the trimming tips below.

 

Trimming Tip 1: Use the trimming ruler.

I used the Slotted Trimmer A. This ruler is designed for trimming HSTs, but it works perfectly for this step as well.

 

Be sure to line up the blue and red lines with the stitching. 

  

Trimming Tip 2: Use the quilt ruler and the painter's tape.

You don't actually need to use the special HST ruler for this step. A quilt ruler and painter's tape will work just as well, or you can use any tape - just be sure it's easy to peel off.

 

Place the painter's tape on the wrong side of the quilt ruler to mark the 3 1/2" points and the stitch line. Refer to the photo above.

 

Be sure to line up the blue and red lines with the stitching. 

  

Press it. Repeat the process with other pieces.

Now you have the perfect Tree-Piece Square Triangles!

 

Happy quilting!