I decided that I should have a rating system for each method of Half Square Triangles….because I’m cool like that. There are advantages and disadvantages to each, but that way you’ll know how I feel about it.
To catch up – visit Part 1: The Traditional Method
Today I’ll show you how to make 4 half square triangles from one square. I don’t know if there is technically a name for this…so I’m going to call it
The Square Stitch Method
I’ve given this 1 out of 5 stars. I do not like this method. There are two primary reasons.
- It leaves you with bias edges. This results in more distortion in piecing and also while pressing (because many of us iron rather than simply press).
- The math is not simple. If you want to get technical it requires the Pythagorean Theorem and you must know whether to take your seam allowances into account before or after using the Pythagorean Theorem.
The sewing is EASY!
PLEASE starch these bad boys! It will help with the bias distortion problem by stabilizing the bias.
You’re going to put your two squares right sides together and simply sew around the entire outside edge of your squares with a quarter inch seam allowance!
Now you’ll make two diagonal cuts, and you’re almost done!
Rotate your mat, or flip your ruler and cut the second diagonal line.
And now you have 4 half square triangles!
Iron the seam to the dark size and trim to size, just like with the Traditional Method.
The math I’ve seen with this method is really poor math (it’s more like a guesstimate) and no one tells you if that results in the the finished size, or unfinished size. In fact, I haven’t personally seen anyone give an equation starting from the finished size that you actually need. And if you’re going to use it to replace HSTs in a pattern, you need to start there. If you’re winging it and making up your own pattern, then you can skip the math all together.
So I a squared plus b squared equals c squared. I figured out seam allowances. I took square roots of numbers. And I tested this on several sized squares to see if my math worked. And all for you. That’s how much I love you. You will get odd numbers, round up. You can always trim down to size later. In fact, I added an extra 1/4 inch already so that if your cutting isn’t perfect, your ruler slips while cutting or your seam allowance is not perfect, you will be safe. (I prefer to trim a little off rather than be too small.)
Ready for some algebra? (Your middle school teacher would be proud.)
Start with the finished size you need and add in your 1/2 inch seam allowance. Multiple this number by 1.414. And lastly add 0.75. This tells you the size squares you need in order to make 4 half square triangles! Whew! And now if our brains have not exploded, we can see how to actually make these. Cut two squares to the correct size.
Be back next Monday with another HST method as part of the
Half Square Triangle Mini Series!
Part 1: The Traditional Method
Part 2: The Square Stitch Method (you’re here!)
Part 3: The Simplified Grid Method
Part 4: The Grid Method
Part 5: Magic Triangles
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