Any quilter knows how to make half square triangles (HST), and there are several techniques that you can use, depending on the number of units you need and the size of initial squares you have on hand. You can make 2, 4 and even 8 units at once- obviously, for 8 units you need bigger squares than for 2 units.
I needed sets of 4 HSTs made from the same fabrics so I used the technique that makes 4 HSTs at once.
You can use squares in any size, I used charm squares (5″ squares).
Here is what you have to do:
1. Place the squares right sides together.
Stitch at 1/4” from the edges.
Trim the piece on both diagonals. Press the seams and square up the units as needed.
I don’t make often HSTs but when I do, the ruler below is amazing for squaring up- you do it in just one step. It is called SQUARE UP ruler from Quilt in a Day.
You align the line of the ruler with the SEAM of the unit and trim along the edges of the ruler.
It’s a very fast technique, especially if you have many units.
The units have edges cut on bias, so you have to press the seams carefully. If you prefer, you can press the units first and then square up them, with the regular square ruler.
Here is some math, so you will be able to work with squares in any size and create HSTs in any size.
You can use the above formulas in two ways:
– if you know the size of the initial square (X), you calculate the unfinished size of the HST unit (Y); then you square up the HST to the needed size.
– if you know the unfinished size of the HST you need (Y), you calculate the size of the initial squares (X).
Before cutting tons of squares, make a test first!
I used my HST units to make two-color 3D pinwheels. These blocks are even more beautiful when made in Christmas fabrics!
And here is my table runner.