If I had to choose the most versatile fabric arrangement for a quilt, I’d plump for the half square triangle. The possible arrangements are endless and half square triangles (HSTs) are pretty easy to make. I’m to talk about different ways to make them at my guild this month so I’ve been reviewing the possibilities.
Here is the quilt on which I learned to make HSTs – hundreds of them. It was part of a class through the now defunct Quilt University.
The most basic construction method is to slap two squares together with right sides facing, draw a diagonal line from one upper to the opposite lower corner, and sew a quarter inch away on each side of the line. Then, cut along the line and you have two HSTs. It’s a great way to use up lots of 2.5 3, or 3.5 inch squares. Permutations of this method include the use of a piece of marked plastic to line up your square so you don’t have to draw the line.
If you want to make more than two HSTs at a time you have several choices of method. Which you use depends in part on the shape of the fabrics you have to work with (squares, strips, rectangles) and the number of fabrics you want to use. Here’s one quilter’s comparison of two methods.
If you have 5 inch charm or 10 inch layer cake fabrics, then put your two fabrics with right sides facing each other, sew a very scant quarter inch around the outside perimeter, and cut two diagonal lines from upper to lower corners. You’ll get four HSTs with outside bias edges. It’s up to you whether you’re comfortable working with that.
For long strips, match up the same width strips right sides together and sew a scant quarter inch along the top and bottom edges. Using a ruler with a marked diagonal line, put the ruler on top of your strips so the diagonal line is at the fabric edge, and make two diagonal cuts from top to bottom. Again, the outside edges will be on the bias. I found this technique at Like Flowers and Butterflies.
If you want to work with squares sized to your HST needs, try the Magic 8 method shown on Craftsy.
For rectangles of fabric, put right sides together and draw a grid of squares on the lightest fabric. Then draw diagonal lines through the corners so each drawn square is bisected by a diagonal line – just one line per square. Sew a quarter inch away from the diagonal lines in a continuous seam and cut the HSTs apart on the horizontal and vertical drawn lines. This is the method I use most frequently. You don’t need to cut your rectangles to a particular size, though it helps if they’re the same size.
The most perplexing aspect of all these methods is how big to cut your pieces to make the size HSTs you need. Some online tutorials don’t talk about this. My rule of thumb is to go oversize. For the grid method I draw my squares half an inch larger than the size I want for my HST. In the example above I drew a 3 inch grid to get 2.5 inch HSTs. The layer cake method gave me 6 something inch HSTs, not a useful size for most projects. The strip method gave me HSTs that were an inch larger than the 3 inch strip width, though I think that varies with strip width.
I know some quilters sew accurate HSTs. I don’t, so I go big and trim down. There are many charts that show how big to cut fabric for HSTs. Most feature adding 7/8 of an inch to the desired finished size. Since I know I’ll be trimming anyway, I just add 1 inch and skip finicking with that 7/8.
About that trimming – some quilters trim their blocks before they press open their HSTs. (See #2 in this post for how.) The key is to put the diagonal line of your ruler on your sewing line. You can use a small square ruler or a specialty one. I don’t do this simply because I don’t have those rulers. Here’s a blog post from A Little Biased that shows the method I use.
I haven’t made many HSTs lately, but I have a container full of them that were byproducts of other projects. Once I get them trimmed I’ll be all set. If you really want more on HSTs you can look at my triangles board on Pinterest.