When it comes to half square triangles there a various ways to make them. The trick is to make them accurate in size. I recently enrolled in a class at my LQS, Stitching on State, in Hampshire, IL. It was going to teach a variety of ways to do half square triangles and applique. Sounded good. Little did I know that the teacher expected us to actually make the complex quilt, Triangle Star, from Laundry Basket Quilts in about 6 weeks. Quilt is below.
Since this would be my first full size quilt, I said I'd try to get half done. So begins the journey. First I needed to do 224 (half of the 448 total needed for the quilt) 2.5" half square triangles. I did try 3 of the 4 ways suggested. Follow below the orange squiggle for how this worked out.
The first way to do accurate half square triangles is to do them 2 X 2. Because of the difficulty in always sewing a 1/4" seam, and always cutting exactly 2 7/8 squares, I cut them at 3". Obviously they could have been 3.5" just as easily and been even safer. At 3", I only had to discard 1 square, and that was because I trimmed it wrong.
Take two 3" squares, for this pattern, one light and one dark, place them right sides together and draw a diagonal line corner to corner. Then 1/4" off that line draw your seam lines. Because the pencil line, I made it more like 3/16".
This picture doesn't show the lines very well, but I put in all three lines, because my 1/4" sewing foot has an outter edge that makes it difficult to do use with internal lines. If you have a 1/4" foot that would work for this, you can just use that to sew off the diagonal line. Then cut on the first long, corner-to-corner diagonal line, open the square, iron the seam towards the dark side, and trim to the exact size (2.5" in this case), and you have it.
If you have to do a total of 448 1/2 triangles (for the whole quilt), this way will take you a very long time.
So, moving on the larger scale production of half square triangles, using larger strips or rectangles to make multiple half square triangles at a time. Below is my first attempt, using a 3" by 9" strip. Most experienced quilters will be able to see the "mistake" immediately. It really isn't a mistake, but a bit of a challenge. By having all the lines going in the same direction, you have to be very careful to stop sewing on the upper line before you sew into the next square.
I was careful and it worked out. I got 6 squares in less time than doing them individually. Referring to the sheet from the class, I remembered to do the angles running opposite.
I did the 6" X 9" rectangle and got the 12 squares. The problem is the you have to trim them to the exact size. For me this took more time than I'd like.
So on to the final way I tried. Thangles.
I had purchased Thangles in the past, but I had never used them. Now, with so many triangles to do, it was time to try them out. I have to say I loved them. I rough cut two strips of fabric somewhat larger then the Thangle rectangle.
Again placed right sides together, pinned the Thangle on top. The directions recommend setting your stitch length to 1.5. My machine, a Babylock Ellura, only does even steps, so I set it at 1.6.
Sew on the dotted line, trim exactly at the edge of the paper, on the black lines in between the squares, and along the diagonal lines between the squares.
Next rip the paper off the 1/2 square triangle. When you rip the paper off, hold the fabric close to the end, so the stitching doesn't distort.
Now, as with all 1/2 sq triangle methods, iron the seam to the dark side. Here instead of trimming to size, you just snip off the one "dog ear".
For me this was a much quicker way of doing 12 half square triangles at a time.
I should add that Laundry Basket Quilts has triangle paper that does 28 half sq triangles per sheet. I did not try that so I can't comment on it.
So for me, the best method of doing half square triangles, meaning for accuracy and speed, was using Thangles.
What quilting project are you working on?