Frequently you need WAY more than a single triangle square (also known as a half square triangle) or two for your patchwork project.
This method gets them done FAST.
By stitching eight at a time.
For 2" finished half square triangles, the calculations are...
2" + 7/8" = 2-7/8"
2-7/8" is our center or midpoint measurement; you'll need it in Step 4.
Multiply the sum by 2...
2-7/8" x 2 = 5-3/4"
Cut one 5-3/4" square from each of two contrasting fabrics.
Mark the two diagonal lines from corner to corner as shown below. I particularly like to use a mechanical pencil to draw these lines because the point of the lead doesn't dull and make a larger, more inaccurate line.
With your favorite quarter inch foot installed on your sewing machine, stitch an accurate 1/4" away from both sides of each line.
If you are more comfortable, go ahead and mark the stitching lines, too.
The Quick Quarter ruler is a good tool for this job—you can also use it to mark the center line especially when you've got a lot of lines to draw.
Press the whole thing flat now to set the seams for all 8 half square triangle units at once.
If you have a small or rotating cutting mat, this is the perfect time to use it.
Cut the unit in half through the 'center or midpoint' measurement computed in Step 1. In this example, the squares are cut in half along the 2-7/8" line.
Turn the mat a quarter turn. And again cut in half along the 'midpoint' measurement. Be careful not to disturb the alignment of the pieces. A small or rotating mat makes this so much easier.
And this is what you have. If you've made triangle squares with Technique #1 this should look very familiar now.
Now cut once on each diagonal line to separate. You can use either scissors or a rotary cutter.
Now press the seam allowance to the dark side (traditional), or to the light side (to reduce bulk or aid construction), or open (to reduce bulk, aid construction or avoid shadowing).
After the dog ears are trimmed (like the upper left block above) you've got 8 perfect little triangle square units ready for piecing into your block or quilt.
To download and print our free cutting chart for this technique in a variety of sizes, click the 'Stamp Out Math' button to the right.
The link will open in a new window. Click the print icon to print a copy to keep by your sewing machine.
The chart contains cutting sizes with exact dimensions, as well as those with some 'fudge factor' built in. I've also included the midpoint measurement for trimming oversized units.
You need Adobe installed on your computer to complete the download.