Patterns From 


Tips! Drafting Half Rectangle Triangles
What is the easiest and most
accurate method of drafting pattern piece for a Half Rectangle Triangle? A Half Rectangle Triangle (HRT) is a triangle that is made by bisecting a rectangle from point to point. A Half Square Triangle is the simplest pattern piece to cut. Simply cut a square 7/8" bigger than the desired finished square and cut on the diagonal. There is no EASY formula for determining the size of rectangle to cut to make the correct pattern piece for an HRT. And it isn't obvious how to line up HRT for sewing into a rectangle. See the chart below that shows finished size, size & shape to cut, overlap and lining up triangles for sewing. Again, a Square HRT, better known as a Half Square Triangle or HST, is easy to work with. But see how the seam line for the notsquare HRT goes through the points of the finished rectangle points but not through points of the unfinished rectangle. So the main problem is figuring out how to line up the HRT for sewing (see my opinion at the bottom of the page). BTW... the math in the From Rectangle column came from Coreldraw so I am not sure how accurate it is but it is accurate enough for our purposes. 
My opinion..... it's easiest
to paperpiece these rectangles. An option would be to draft the
finished rectangle on paper, bisect it, add quarter inch seam allowances all
around one triangle, duplicate that triangle, line up the paper triangles as
if they were two patches to sew together  use alignment pins to match
the points of the finished triangle  then trim any paper that hangs over
edge of the other paper triangle and use this paper as a template for
cutting HRT that can be lined up accurately for piecing. Don't forget that cutting HRT patches from folded strips will result in half the sewn rectangles being mirror images. This may or may not be what you want..... 
Contact Information: Quilt Design Northwest 

Last Updated on December 16, 2006 