How to Make Half-Square Triangles

Making HSTs is really quite easy. I can’t begin to count how many I’ve made over the years, and I always use this process. It’s just too simple to consider changing. These directions will give you one HST block. I wrote this tutorial in 2012 when I made this quilt for a student who was getting chemo treatment. That’s quite a long time, so I decided it’s time to update it.

Please try to ignore that little white tail.

To begin, you’ll need to cut square patches. As long as the pieces are square, any size will work. If you want a specific size HST, add 7/8″ to the size of the unfinished block. I think of it as starting with what I know, the size of the unfinished block, then add the 7/8″.

But you may not think like I do. So, let’s say you want a block that finishes at three inches, cut your squares 4 3/8″. Why, you ask? Let’s do the quilt math! 3″ finish + 7/8″ HST seam allowance + 1/2″ block seam allowance. 3 + 7/8 + 1/2 = 4 3/8″.

Now that you have the math down, cut your pieces. Generally, you’ll have an equal number of darks and lights. If you’ve chosen medium fabrics, determine whether your fabric pencil will show. If not, add those pieces to the dark pile. Now draw a diagonal line on each of the light squares using a ruler and fabric pencil.  

Placing a light piece on a dark one, chain stitch precisely 1/4th inch from one side of the drawn line. After all of the pieces are sewn, turn the entire chain around and sew the other side, again 1/4th inch from the line.

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Now snip the chain stitching thread. The use your rotary cutter and ruler to cut the square in half exactly on the line.

Press the block toward the dark side.  In these photos, I used a dark thread so that the seams would show, but in reality I used a grayish blue in a medium tone.  It’s time to snip all those little corners off. Extra tip: put some wide tape (sticky side up) on your work surface. It will catch the snips as you go.

I played with the HSTs just to give you an idea of some of your options.

Straight lines
Straight setting
Chevron or zigzag

Hope you enjoyed my tutorial on half square triangles.  I had fun making the quilt and playing with the blocks.  

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