Sunday, March 27, 2011

The Basics of Pinwheels...

...or, Two Ways to Piece HSTs


For two more ways to piece HSTs, check out Piecemeal Quilts.


My first (and honestly, long abandoned) method for HSTs is about as traditional one can get, short of fashioning templates out of cardboard and drawing the shapes out onto the fabric back.  Thankfully, due to rulers and rotary cutters, we don't have to go quite as traditional as we could:


First of all, some basic math - or the 'magic number' for Half Square Triangles:


7/8"


That's it.  Add 7/8" of an inch to the desired FINISHED size of your HSTs.  In today's case, that means that our starting squares should be cut at 3 7/8" by 3 7/8".  Notice the words 'should be'.  I'm not, nor will I ever claim to be, a perfect cutter.  Mistakes happen.  I personally add at least the 1/8" needed to bring it to an even number, and trim down.  I add more leeway if I know I've got the extra fabric.  So, go ahead and cut two squares each of your light and dark at 4" by 4".  In my case, I cut one square each of the two prints, and two squares of the dark brown solid:
Now, go ahead and cut these on the diagonal.  Yup, just slice those babies in half.
Pair up your light and dark halves and sew them together.  Be careful!  You are now sewing on the bias edge - this means that the fabric can stretch, so do your best to not pull the fabric.  Just let the feed dogs take the fabric as naturally as possible.
Snip your pinwheel quarters apart and iron as desired.  I'm a seams open kind of gal, but don't feel like you have to do the same.
 
Lay out your sub-units, ensuring that the pinwheel is spinning correctly, with the print fabric leading the whirl around:
Stitch together - I chain piece.  Sandi offered an excellent piece of advice, about leaving the two halves of the pinwheel together, to ensure that they continue to face the correct directions.  I'd never thought of that.  Sew your two halves together.  If you've ironed your seams to one side, I suggest referred to Sandi's tutorial.  She offers some excellent advice about nesting your seams and how to not cut off the points of your triangles.  Since I press open, I have to trust that my 1/4" seam is accurate.  Anyway...

VoilĂ !  Pinwheel!
Now, onto the second method, which I prefer by far:

Cut a 4" X 16" strip each of your light and dark.  In my case, I cut two strips of each of my prints at 4" X 8", and two strips of my solid at the same size.
On the back of your lighter fabric, draw lines at each 4" mark.  Then draw in the diagonal lines from corner to corner in a zig-zag.  For the moment, these are your guidelines, but they will be your cutting lines later.  You can opt to draw in the sewing lines, 1/4" away from your cutting lines.  If you do, you'll notice that this looks an awful lot like Sandi's Triangle Paper.
Stitch 1/4" on either side of the lines that you just marked, following the zig-zag pattern:
Slice along the 4" markings:
Then cut along the diagonals:
From here, continue on with the finishing steps from the first tutorial above...  Press your new squares open, and stitch your pinwheels together.  Having done both methods here, I think you'll see, easily, why I prefer to stitch my HSTs in strips.  I'm not piecing on the bias, so there's less distortion.  I'm not chain piecing so much, and seams are far more accurate this way.


If you've followed Sandi's tutorial, here, then you'll have four 3.5" pinwheels that you can make into a 12.5" block. My block:
Have fun with this! And if there are other topics you'd like to see covered very soon, leave a comment!

3 comments:

Needled Mom said...

Great tutorial! Thanks.

piecemealquilts said...

How is it that you can cover exactly as much info as I did and keep it so concise?! I need to learn to edit - I talk way too much. Also, I love that we chose such completely different fabrics, but both chose to incorporate solids and larger scale prints.

Sharon said...

Great tutorial and you spent a lot of time too.

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