Turkey, the Macy's Parade and Setting Triangle Math

My Thanksgiving morning was perfectly nostalgic. Up early to put the turkey on and make a nice breakfast. followed by watching the Macy's Thanksgiving parade on TV . . .  updated a bit because as I watched, I cut setting triangles and assembled a Christmas quilt top from those old swap blocks.

With a large design wall, it was a lot easier to figure out what I meant by my mysteriously coded sketch and lay out the blocks.

It seems I always have to go look up setting triangle math, whenever I put blocks on point.  I know that the magic number is the square root of 2–1.414–but I never remember what to do with it ... so off to the computer I go.

Here's how I will remember NEXT time:

• Since I'll need MORE side triangles, I MULTIPLY the finished block size by 1.414.  Then, because I am going to cut the square into quarters, as for quarter-square-triangle units, add 1 1/4 for the seam allowances.
• For the corners, I do the opposite and DIVIDE the finished size block by 1.414.  Because I am going to cut them diagonally in half, like half-square-triangle unites, add 7/8 inch.   

For both kinds of triangles, round the measurements to the nearest 1/8 inch ... so you can easily cut them.

For the corners, I used the twelve inch star block as the starting point.  12 / 1.414 + 7/8 = 9 3/8 inches.  Because I inserted six inch 4-patches into the side setting triangles, I used 6 in the side triangle math. 6 * 1.414 + 1 1/4 = 9 3/4.