Lesson # 3 - Triangles
Triangles are a shape that is used over and
over in quilting designs to make a multitude of blocks and designs.
This exercise is only going to deal
with one kind of triangle- the half square triangle.
As you look at the picture above,
you can see that this triangle has 2 short sides, and 1 longer side.
The longer side is called the hypotenuse.
Diagonal seams are very fragile as
far as being prone to stretching and distorting your quilt. You
have to be very careful with them.
When you want the short sides of
the triangle to run parallel to the grain of the fabric, the hypotenuse
will be one the bias.
Other times you will want the
hypothesis to run parallel to the grain. One example of this is
when quilt blocks are diagonally set- and triangles are used to fill in
the sides of each row.
Cutting a Triangle
One of the easiest ways to cut a
triangle is to just make a square and cut it in half on the diagonal.
If you are planning on making squares by sewing the two triangles
together, you will have to add 7/8 of an inch to the width of the square
for the square to come out your desired size when sewn.
Important- the 7/8 of an inch is for the FINISHED SIZE OF THE TRIANGLE,
which includes the seam allowance, no matter what the size of the
If you want to
make a "raw block", just add 3/8 of an inch to the square size.
You can either cut it in half to sew to another piece of fabric, or you
can put two squares together, draw a diagonal line from one corner to
the opposite corner, and then sew 1/4 inch on both sides of it.
You would then cut on the drawn line and have two half square triangles.
(See "another option" below)
Practice cutting some of your
quilt squares in half, and then sewing them together again.
You may have a problem with
starting the points under the presser foot. See
If you are using 4-inch
squares, they should measure 3 5/8 inches if you have cut and sewn
two 4-inch squares right sides together. Draw a diagonal line
from corner to corner.
Sew 1/4 inch on each side of
the line, and the cut down the middle.
You will have 2 identical half
square triangles. They should measure 3 5/8 inches. The
seam allowance takes up 3/8 of an inch. Bear in mind, when these
triangles are sewn into a project, you lose the seam allowance, so
they will finish at 3 1/4 inches.
Note: Another important triangle is
the quarter square triangle. It differs from the half square in
that the bias is on the short sides. You use these on the edge of
a quilt for a diagonal set.
You will learn
a quick way to make 8 triangles with two squares of fabric in the
Pinwheel Challenge Block.
You will learn to make quarter inch triangles in the Quarter Square
Triangle Challenge Block.
Here are just a few blocks that make
use of the three shapes you've learned so far: