Hexagon Heartache

Once I got the last border on the triangle quilt, I decided it was time to refocus my attention on it and work on the back.  Except I had no idea what to do on the back, although I really wanted to use fabric out of my stash, since almost none of the front is from my stash!  I've had a really cute fabric bundle from Fabricworm since two Mother's Days ago (when I bought my own gifts, thanks very much).  My original plan for it never really came to fruition, so it just sat around.  

While browsing quilt backs on Pinterest, and saw several that had hexagons and just knew that's what I needed to do!  At that time the quilt front was still laying on the floor so I was able to estimate how many I would need.  Then I got cutting, using my isosceles ruler that I used for the front.

But when I laid them out...

This is not a hexagon!  What madness is this?

Seriously, I couldn't figure it out.  I blame it on my 3 year old "assistant" distracting me. ;-)  I could not figure out how to get these triangles to become a hexagon.  I would have looked at the quilt front, but it was folded up in a safe place.  So I googled it, was not happy with the results, and finally decided to just trim all 36 triangles into equilateral triangles.

Back layout is inspired by this tutorial.

I was happy to see the hexagons come together so easily, but then had to figure out how to make a half triangle template.

I found this awesome tutorial on how to make a half-triangle template with seam allowance!

And then I needed to get out the quilt top again to make sure I had enough hexagons, and suddenly I knew how to make the isosceles triangles into a hexagon!  Major D'oh moment for me:

The key here (compared to the photo at the top of this post) is that the top points of the isosceles triangles alternate up and down.  I had made the mistake of thinking they should all point towards the center!  

 Oh le sigh!  But oh well, at least the quilting won't clash as much on the back.  So here is where I am, though I have started to sew them all together:

Brown on the left and purple on the right.

 So tell me, have you ever made a triangle or triangle-hexagon quilt?  Did you ever run across any of these problems?