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Ruler Tutorial – The Quilt in a Day Half Square Triangle Ruler ( video tutorial )

Today’s post is part of a series of video tutorials showing you how to use some of my favorite rulers.

Find more ruler tutorials here.



Today I’m showing you how to use the Quilt in a Day half square triangle ruler.

I wish I had my first half square triangle quilt to show you.  What a disaster!  It was one of those chevron quilts, you remember when they were popular, don’t you?  If not, there was a day when chevron was the thing.  I was very new to quilting.  I cut a whole bunch of squares, I cut the squares in half and then sewed the two halves together (insert face palm).  But if I’m being honest even after I realized you could make two at a time and not cut the squares in a half I still STRUGGLED HARD.

They were wonky.  They were janky.  I hadn’t learned my “ritual” yet.

I bought the above ruler on a whim.  It came with instructions!  Then I kept doing it and doing in and doing it and finally I can say that I have no issues with my HSTs.  They are my perfect little babies now.  If there is a mistake in my quilt block, if it doesn’t measure up correctly, if something is a bit off, you can bet your fannie it isn’t because of my HSTs!


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We’ve got a lot to cover today, so I’m diving in and getting to it quickly.  No funny business!

Let’s go over some quick “you should know” things first.

  1. Decide what size your HST should be finished.  Let’s say that I want it to be 4″
  2. I need a trim-to size.  I need seam allowance.  This means my unfinished HST needs to be 4.5″
  3. If I’m trimming this guy to 4.5″, I can’t start with that size, I need seam allowance again.  So you add another .5″ to that and your starting square size is 5″.
  4. This method of making HSTs makes 2 of them at a time.

Back to the math… If I need an unfinished 6.5″ HST, that means I need to start with 7″ squares.  If I need a 2.5″ unfinished HST, that means I need to start with 3″ squares.  You get it!

Finished means it’s sewn all up into a quilt.  Unfinished means we haven’t sewn them together yet, they are a unit or a block.  Still with me?

If you are very lost here and think you might need a more detailed lesson about seam allowance, here’s a class that might help.


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Avoiding that jankiness

Let me just get this out of the way and tell you that obviously my method is NOT the only method.  There are lots of lovely methods and you should find the one that you like the best.

Anytime you cut a fabric into a triangle, you’ve made it stretchy, you’ve made it vulnerable.  Vulnerable to ALL THE THINGS!  I like to call them the precious little babies, because that’s how you are going to have to treat them if you want them to act right and stay in place and stay not-janky.

Here’s a list of things NOT to do:

  1. Don’t stretch them.
  2. Don’t iron them, press instead.  PRESS.
  3. Don’t tug at them.
  4. And for goodness sake, use your starch.  It is your bestest friend when making patchwork.

So as you can see, I’ve got some hard rules set here.  LOL.  I can be quite the school marm about my HSTs.  This is serious business!  In my opinion, taking the time and getting this right will save me so many headaches as my quilt progresses.  HSTs are in SO MANY QUILT PATTERNS.  They can be quite the little you-know-what!  For that reason, I don’t get ahead of myself, I don’t rush and cut corners.  I do the ritual step by step and that’s that.  You can try to save yourself some time by doing the steps in batches and by chain piecing, but don’t skip on the ritual.


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HST step by step (aka My Ritual)

  1. Cut two squares with your starting size as mentioned above.
  2. Draw a diagonal line on one of the squares.
  3. Place squares on top of each other right sides together.
  4. Sew 1/4″ from both sides of the drawn line.
  5. Cut the square in half by cutting directly on the drawn line.
  6. Using the Quilt in a Day HST ruler, trim each unit to the unfinished size needed.
  7. Press to set the seams on each HST, then press seams open.
  8. Spray HST with starch, and press again.



My Quilt Patterns


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I hope you found this post and video tutorial helpful.  I do love a good HST, don’t you?  You can find the Quilt in a Day Half Square Triangle ruler available here for sale.  If you are joining in during the Little Miss Sawtooth quilt along, you’ll see me use this HST method over and over again in my video tutorials.  There’s a lot of HSTs in that quilt!  But you’ll also see me use this same ruler in a whole different way of making HST, but instead of squares, it will be with strips.  Later this year, I’m also sharing a quilt pattern that has another way of making them using the very same ruler.  I can’t wait to show you.

Have a lovely weekend!


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  1. I bought one of these rulers on your recommendation but I couldn’t get it to make the HSTs the right size. I was making 4.5″ squares but they are too small when the dashed line was on the stitch line and when I tried moving the dashed line (above or below the stitch line – I can’t remember which way now), it was still too small. In the end I just used a normal ruler to get the HSTs the right size. I was quite disappointed. Any ideas what went wrong? My fabric was starched before I did any sewing – that’s the only thing I can think of as being different.

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