Making Half Square Triangles

I've been a busy bee lately finishing up projects and writing new patterns, so today I thought I would give you a little snippet of one. I made the quilt at right for the Michael Miller challenge to the Modern Quilt Guild. I call it tilt. I'm not quite ready to release the pattern yet, so here is a tutorial from the pattern on making half square triangles

When quilters talk about half square triangles, we are really talking about a square block that is made up of two right triangles. There are several ways to make them, and today's tutorial is about my favorite.

Obviously you could cut two right triangles and just stitch them together. But that is always a little tricky. You have to line them up just right to end up with a truly square block. 

The easiest way for me to make perfectly square units quickly starts with two squares that are larger than the finished half square triangles. In today's example, I cut two 4 inch by 4 inch squares to end up with two 3 ½ inch half square triangles which when sewn into a quilt top will finish at 3 inches square.

Other tutorials will tell you to calculate the size of the square you need to cut by taking the size of your finished square and adding 7/8 of an inch. However, I like to add a full inch as it gives me a bit of fudge room to square up the block after sewing and pressing.

Layer the two squares with right sides together, and with your ruler and a washout marking pen (or any fabric marker you prefer) make a diagonal line on the back of one piece of fabric. Generally choose the fabric where the line is going to show best. Here I have drawn the line on the white fabric.

At the sewing machine sew a scant quarter inch seam on one side of the line, removing pins as you sew.

Flip the piece around and sew another seam on the opposite side of the line. Trim your threads and return to the cutting board.

Use your ruler and rotary cutter and divide the piece along the line you drew (and between the two seams). Now take the two pieces to the ironing board and press each open, pressing seam allowances toward the darker fabric.

If you are anything like me these two half square triangles might be a bit wonky. This generally happens because the steam used in pressing has stretched the fabric just a bit. Never fear! That is why we cut the original squares at 4 inches instead of 3 ⅞ inches. Go back to the cutting board and using a 4 ½ inch ruler (or whatever ruler you have), trim up your square to be exactly 3 ½ inches. The advantage of this specialized ruler is that you can line up the diagonal on the ruler with the diagonal on your square to make sure you take extra fabric from the sides equally.

Voila! Two half square triangles in the time it would have taken you to make one. This is the method I always use if I want to make lots of half square triangles but they need to be from different fabrics.

If you need a big bunch of half square triangles that are all the same, the easiest way is to take two much larger squares, sew around the outside edges and then cut twice diagonally, but that is a story for a different day.