Determine fabric for each block. Again, I can see from the picture that I have 4 squares of focus fabric and 1 square of light background fabric, each will be cut to 4 1/2" square.
For the four corner half-square triangles, I cut two focus fabrics and two light background fabric 1" larger than my required block size....in this case 5 1/2". That's my 4 1/2" block plus the 1". Lay the light background on top of the focus fabric and draw a diagonal line from corner to corner. I use a light pencil. Sew 1/4" on either side of the line. Cut on the drawn line and press toward the dark. The beauty of over-sizing this block is that you have fudge room to square it up to perfection. Every one of your half-square triangles will be the same size with no wonkyness about it at all.
You can see here the four corner blocks are needing a trim down to 4 1/2". After I do this, I will line the rows up and sew each block to completion.
One block down, 30 more to go to make my 60" x 72" shoo-fly quilt.
Oh, well! Might as well use them. I took some of the left over fabric and pieced it together for the backing. Added one of the left over shoo-fly blocks off-centered in the top corner to satisfy my need to add a taste of modern to this traditional quilt. It was a beautiful spring day when I got these pictures in my back yard.
Shoo-fly No. 2 used up four more of my left over blocks and more of my fabric left overs. I'm determined to get this out of the house! Adding three borders gave me a 42" square quilt for a table topper or child's floor quilt.
And, finally, more left overs and the final shoo-fly block for the back of the table topper.
Shoo-fly blocks are so fun when super-sized. I made two super-sized quilts a couple of years ago. Here's one pictured. Again, I first made the decision that I wanted my quilt to be approximately 72" square. Okay, that must mean that each block is 36" square. Which means that the four square focus fabrics and one background apple green fabric in each block must be cut @ 12 1/2" to get my finished 36" square shoo-fly block.
Taking it through the final math step, the two focus fabrics and the two apple green background fabrics would need to be cut 13 1/2" to get the perfectly trimmed half-square triangle blocks. I added an apple green border all around to float the shoo-fly blocks in the quilt top. It's washed and dried and smelling fresh as sunshine.