How to Make HST Quilt Blocks using Magic

Have you ever needed to make a lot of identical Half Square Triangle Blocks (HSTs) for a quilt or other quilting project?  It can be daunting, but not if you use Magic!  Here is a way to make 8 at a time, quickly and easily.

[A quick note from Kris: I ended up making a quilt topper called the Midnight Star Table Topper from the blocks I made in this 4 part tutorial series.  If you make one too, please send me a picture so I can brag!]

This is a Four-Part Series of Tutorials. 

How to Make Eight Identical HST Quilt Blocks Using Magic

The trick to this method is to use one seam to sew more than one HST at a time. Like any magic trick, it needs a little bit of prep work. First, you need to cut two oversized squares, the dark and light of your HST block.  To determine the size of the square you will need, you double the size of the finished square and add 1-3/4″.   For example, if you want to end up with 4″ HSTs, you would start with a 9-3/4″ square. (4 times 2 is 8, plus 1-3/4.)

In this example, I am using 10″ squares.  That’s to give you a little bit of room to square up your blocks afterward.  If you are very confident of your seam allowance, reduce these squares to 9-3/4″ square.

Start with:

  • (2) 10″ x 10″ Background Squares
  • (2) 10″ x 10″ Blue Squares

I used the Stripology Ruler to cut my blocks. In the first picture, I am cutting a zero line on the left side of my fabric. To get the straight of grain, place a horizontal line along the edge of the fabric before cutting on the zero line to start your cuts.

After I cut the two blocks, I pressed them in quarters and then on the diagonal.

You can see my Oliso Smart Iron in the picture above.  I love the fact that it raises and lowers automatically.  Just touch the iron handle and it lowers, ready to press.  Take your hand off and it lifts off the board.  And yes, you can turn off that feature on the back of the iron.

But I like not lifting that heavy and HOT iron up on its heel and worrying about tipping.  It’s expensive, but it is worth it for the self lifting feature alone.

Picture of a quilt block being prepared for cutting

On the back of the Background squares, draw 4 lines: one vertically through the center; one horizontally through the center and one on both diagonals.  Use the pressing lines as your guides.  These will be your cutting lines.

Put your Background Square and your Dark Blue square right sides together.  Sew 1/4″ on both sides of the diagonal lines. Since you are making 2 squares, you will probably find it easier to chain stitch these.

Graphic Showing Magic Eight Sewing Lines

Just sew all the centers first, going from one block to the next without snipping the thread in between the blocks.  When that is done, you can do the other side.

I drew lines on one block and just used the fold marks on the other to see which method I liked the best.

Press your sewn block.  Don’t move the iron.  Just press with a hot iron in an up and down motion.  You want it to lay very flat before cutting.  If you cut it apart using a rotary cutter, take care not to move the squares with each cut. A rotating cutting mat will come in very handy.

Picture of a Magic Eight square cut 8 ways
This one had the drawn lines, but you can’t see them as I cut through them.

When you have all 16 blocks cut, you will need to square them up.  If you have a specialty ruler like the Triangle Square Up Ruler by Quilt in a Day that squares up HSTs, you can place the ruler so the line is directly over the seam and just cut one edge.  (see below)

A block being squared up using a quilt-in-a-day-ruler
This is the Quilt In A Day Triangle Square Up Ruler.

If not, you will need to press open the block (pressing to the dark) and square it up to 4-1/2″ x 4-1/2″.  This is the Creative Grid 4-1/2″ Ruler. It has a diagonal line to match up with the seam.

When you are done, you will have 16 identical HST blocks.

I do have a PDF that goes along with this tip.  You can find it here.  Please don’t copy it and share it with your friends. Send them to this page so they can see the pretty pictures. It does make a difference. Thanks!

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