Of course this is just one way to make half square triangles, but my favorite way especially for using scraps. To make two x half square triangles you need a light square and a darker one cut to the same size e.g. 3and 3/8". This will make a 3" block.
Using a Sewline pencil, rule a diagonal line on the light square. I like to use a sandpaper board to keep my fabric stable.
Place the two fabrics right sides together, and using your 1/4" foot, machine sew down each side of the ruled line.
Press to the dark side. Trim dog ears to reduce bulk if desired.
There are many many designs that you can make from these wonderfully versatille "squares".
Some of you will be beyond this information, but I
also have to consider new quilters who may not have had experience with this technique. Many people
say the key to these is to add 7/8” to the measurement, e.g. if you want half
square triangles to match a 5” square, make your squares to do the triangles 5&7/8”.
Mostly I think this is for the folk that like to then cut their triangles down
to size. I have just made many 3” ones, cutting the half square squares to
3&3/8”- worked perfectly and no need to cut down.
My tip for making many of the same type of block is
to trial one, then make sure that is accurate before you cut the quantity
needed for your project.
I have been making lots of half square triangles for a quilt design by Kerry Gillespie (Toy Shelf) -check it out on my blog under Kerry Gillespie.