How to Sew Half Square Triangle (HST) Quilt Blocks

February Craftsy Block of Month Balkan PuzzleI’ve now made February’s blocks for the Craftsy 2012 Block-of-the-Month. Both blocks use all half square triangles (HST), but use different methods to make the HSTs, which I will explain below. For a video demonstration of the methods, register for the Craftsy class – it’s free! This is the Balkan Puzzle Block. I think this is a fun block and it’s fun to know that it was popular in the 1930’s.

February Craftsy Block of Month chevronThis block is called a Chunky Chevron block. It’s more modern. Picture it in bright solids across an entire bedspread? You can see one of my triangles ended up a little bunchy. I’m going to rip it out, trim that bunchy edge, and sew it back in.

Having sewn four blocks for this block-of-the-month quilt, I’m already regretting my decision of fabrics. I like my olive background. However, the homespun (i.e. loose-weave) plaids are driving me nuts. I hate that the plaids never line up. Much of this is due to the way the blocks are constructed. Many of the plaids I picked are not square so it would take cutting every piece individually to make the plaids line up, not something I’m going to do while I’m learning to quilt.  The other part of the problem is the loose weave of the fabric that makes it very very difficult to cut the fabric exactly on grain as it slips around and stretches out of shape. But, this is a learning experience and I am certainly learning, so onward ho!

HST method 1The class introduces two different ways to sew half-square triangles (HST), a very common unit of construction in quilts. This first method is a modern trick. You place two squares right sides together and then sew your 1/4″ seam all along the edge of the square. Then, you cut it open across both diagonals. When you press the squares apart you have 4 HST. The catch is that the edge of the squares are all on the bias while the grainline runs along the diagonal seam, making these more challenging to piece together as bias edges stretch.

HST method 2The more traditional method to make HST is to place two squares, right sides together, draw a line along one diagonal and then stitch 1/4″ away from the line on either side. Then you cut along the drawn line. When you press the squares open you get 2 HST with the bias on the diagonal and the edges on the grain. For perfectly sized squares, you can pick larger starting squares than necessary and trim you HST down to size.

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