How to Make Half Square Triangles Two at at Time

Making half square triangles 2 at a time can seem like a daunting task, but it’s really not as hard as it seems. In no time, you’ll be a pro at this basic quilting skill and be moving on to bigger and better things! 

You want to start with 2 pieces of fabric. You can use whichever colors you want. It’s traditional to use a dark color with a light color, that way you have some contrast to it. If your fabric is directional with a right side or wrong side, you want to make sure you put your right sides together.

You want to measure your squares out about ¾ in bigger than you need your finished pieces. In my example, I’ve measured mine out at four and a quarter inch square to make these two and they're going to finish at three and a half inches before we put them in our quilt. Once they're all sewn, that half inch is going to shrink to be 3 in. square.  

To get started, you’ll want to draw a diagonal line from corner to corner. Make sure to have your ruler off the corner, just a touch so that your marker is hitting the corner. Otherwise your line will be off centered just a little bit. We're going to sew on either side of this line at a quarter inch.

Let's go to the sewing machine 

Alright, this time I have my quarter inch seam guide foot on here and this bar is a great guide because I can set that bar right on my line and my needle will be a quarter inch away from my line perfectly.

Lift the foot, and place that bar right on the line. Now if you don't have a quarter inch  guide foot, you can use a seam so easy tape and line up your corner with that line at the bottom. Now, we're gonna stitch a quarter inch away from that line all the way down, and sew right off your block. 

So you’ve sewn off your block. You want to lift the foot and leave it attached to the machine. You should still have some thread here. Just pull it out.  And then readjust it so we're going down the other side of your drawn line.  This way we're saving on thread by chain piecing this one block. Now you can chain piece all of your blocks if you're going to make several of these that are two at a time.

You Spin Me Right Round

You'll just sew down one side of all of your blocks and then spin them around and sew down the other side. Up next, you will take your blocks to the ironing board and flatten out those seams. If you want more info on how to do that, check out my detailed instructions in this blog post.  Ironing your seams is going to help all those fibers that might have gotten squinched up with our sewing to lay back flat before we trim it. 

We're gonna cut these apart right on that line that we drew, which will be a quarter inch away from both of our seam lines. And here we have two half square triangles. So let's iron those towards the dark side, or open, whichever you prefer.

I like to use a clapper here, which helps take the heat away from my fabric, and it really helps make them flat. I like working with really flat blocks, but I don't want to necessarily use steam, water, or starch on my fabric unless I have pre-starched or pre-washed my fabric. Otherwise, it may shrink my block. 

Let’s Trim Them Up!

Okay, so now let's trim them up. You want to put the diagonal of your ruler on the diagonal of your block, and make sure that you’re trimming these to three and a half.

Make sure the three and a half line has fabric on the outside of it a little bit so that you can trim all four sides. The diagonal on your ruler should still be on the diagonal of your block.  Remember, use one smooth motion cutting, no pizza cutting. And hold your ruler firmly so that it doesn't slip on you.

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