How to Sew PARTIAL SEAMS

Here is the block I've called the "chained pinwheel."

The "frame" pieces in the Chained Pinwheel enclose the pinwheel in an offset way.  These need to be sewed with what is known as a "partial seam".

First, sew the Center Pinwheel entirely.

Next, sew the "frame strips", you'll need 4 of them.  You will be matching the squares which will form the chain links to the appropriate corner in the above pinwheel picture.

Next will you will sew the first strip to the pinwheel.  The first strip is only "partially sewed", thus the name "partial seam."  Match the colored square to the same colored triangle.  Sew until you are about 1 or 2 inches from the end of the pinwheel.  Backstitch to secure, cut the thread.  There will be a "flap" that you will be able to move out of the way later.

Rotate you block 90 degrees clockwise.  Align your second frame strip, matching the corner colors.  This strip will fit the block, sew the entire length as usual.

Rotate you block 90 degrees clockwise.  Align your third strip, matching the corner colors, sew the entire length.

Rotate you block 90 degrees clockwise.  Fold the "flap" from Frame strip 1 out of the way.  Align your 4th and last strip, matching the corner colors, sew the entire length.

Now you can go back and finish sewing the partial seam from the first strip.  Fold the flap back into place, align the edges.  In the seamline, find your sewing line and your backstitch.  Starting a little before that backstitch, about a half inch or so, do another backstitch to secure this new line of stitching, start sewing again, right over the first backstitch, and sew to the end of the strip. 

Voila!  Your block is complete, and beautiful no doubt!