Using that particular method leaves all the tri's with bias edges that you will be joining together.
Another method that will make 8 HST's is to sew on each diagonal (1/4" on each side of both diagonals, so 4 total sewing lines), then you cut down each diagonal. This way the straight of grain is the unfinished edge of each HST and much easier to sew.
Here's the Tute
http://www.quiltingboard.com/tutorials-f10/fast-way-do-8-time-half-square-triangles-hst-straight-grain-edges-t141047.html
And another with sizes at the bottom ...
http://sewnwildoaks.blogspot.com/201...8-at-time.html