Coincidentally, I was just looking for the Maths for this. Thanks for taking the time and the photos (most of us have to have pics too).
Annie

This is wonderful, I wish I remembered how to bookmark it for later.

Wow great help.

Murphy1, go to 'thread tools' and 'subscribe to thread' then it will show up in the quick links under subscribed threads.

I am new to quilting and this is so helpful. Thank you!!!

Is there no end to the genius of the QB group! Thank you, thank you.....I have a pile of HST to do and I was dreading it.

Thank you Lucy. I'd never seen this method but I like it. So neat.

Thank you, how timely! I was just going to make something that requires these. And I am also doing 4 inch square! Perfect. I will let you know if I run into problems. Thank you :)

Hi LucyInTheSky, I got a different result by chance. I wasn't reading carefully, and accidentally cut them diagnolly (instead of cutting across like you did), I ended up with 8 "hour glass" blocks; using the same measurements you gave. For 4.5 inch squares (before piecing), I started with 10 1/4 inches, sewed diagnolly & then made 4 cuts, I think.
So, I am happy for the simple method & the formula you gave.
Thank you so much.

http://media-cache-ec5.pinterest.com...iJfGZXo6_c.jpg
Found this online if you need the math done for you.