Tuesday, March 1, 2011

Charlie Brown Quiltalong Part 3: Making Half Square Triangles

Making a half square triangle (HST for short) is such a useful skill to have.  I've made hundreds in my few short years quilting and I will probably make thousands before it is all said and done.  There are a lot of methods from Thangles to grid paper to accuquilt go cutter HST dies.  My method is low tech and old fashioned. 

For our quiltalong we need 12 9.5" yellow/black HST.  I always add 1" to my desired finished size to see what size I need to start with.  That means we are going to have 6 black 10.5 squares and 6 yellow 10.5" squares.  (If you are using another color, just sub that for yellow/black).

Step 1: draw a diagonal line across your lighter colored squares. Lay your lighter colored square on top of your darker colored square

Step 2: Sew a seam 1/4" away from both sides of the drawn line.

Step 3: Cut along the drawn line.  You can use scissors or a rotary cutter.  I use the rotary cutter to save my hands from cramps.

See how you now a seam 1/4" away from from that center line?

Now I always put my HST LIGHT SIDE DOWN on my ironing board.  This ensures the bulk of my seam will go toward my darker fabric.  Imagine how ugly it would look to see black fabric peeking through the seams behind white fabric.   I then run my iron over the seam.  This is called setting the seams.  I saw this on Missouri Star Quilt Co. videos and it works.  It gives you a very crisp line when you open up your HST.  Once your seams are set, you just flip that dark side over and press again.  I push the fabric with my iron and let the iron do the work.  I don't pull and tug on my HSTs.

 Now take your square ruler.  It doesn't matter what size it is, you just want your ruler to be larger than your finished HST size.  I happen to have a 9.5" square so that's what I used.  You want your center line on your HST to line up with the diagonal center line on your acrylic square.  I go as close to the edge as I can and trim up the top and right side (I am right handed).
After that, I turn my square so that the clean edge is now the left side and bottom side.  Line up the diagonal line on your grid on top of the diagonal line on the HST.  I can just cut off the extra since my square is my desired size of 9.5".  If you wanted a 7.5" square, then just line your clean edges up at the 7.5" mark instead of the 9.5" mark.

Up next, Piecing your zigzag!


  1. You want an easier way for half square triangles? Place a dark square on top of a light square; sew one fourth of an inch all the way around the edge of the squares, then slice diagonal down the middle in both directions.

    Here is a video of it:


  2. Oh, well I guess that would be quarter square triangles. Duh. Never mind. I am going to bed. I'll catch up on the rest soon.

  3. You were right- it's hst. It will produce bias edges so that is why I stick w the old way. I try to avoid bias at all costs!

  4. I got this part done just now! Woo Hoo! May for Me!


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