Quilt 14: Triangles Short-Cut

Quilt 14 will have 15 of these blocks:

As you can see, there are triangles in this one - 8 large ones and 32 little ones. I'm not really wanting to cut out a lot of triangles and then fiddle with them, not when I know there's a shortcut!

A friend of mine (who happens to quilt and blog!) posted a tip on her blog (have a look here) for making triangle blocks. It's brilliant! It basically involves stitching the edges of a square and then cutting diagonally through it twice.

I want to make my triangles using that shortcut. But the smaller triangles in red and dark blue in the diagram above will be striped material. Will the shortcut cause any headaches with that? And have I correctly calculated the size of the starting block so that I end up with a finished patch that is 3.5 inches square?

I've grabbed some scraps just to test it. I've cut 2 squared at 3 1/8, then stitched around the edges with a 1/4 seam allowance, then cut once diagonally:

Then I cut again diagonally, and now fold back to see the result (as you can see below, I deliberately sewed right side facing wrong side so I wouldn't get confused about the directions of the stripes.

Below is the finished square. It is exactly 3.5 inches, just as I wanted it to be. But I can see a slight problem in that the stripes end up in different directions. Yeah - a bit of a headache, but as long as I'm careful about how I match up the triangles as I assemble the blocks, I should be able to complete a harmonious design.

OK. Time to do the math:

32 little triangles
  8 big triangles
  1 center square
----------------------
41 pieces per block

15 blocks in the quilt give me 615 pieces in this quilt - and that's without the borders!