Originally Posted by
Neesie
Go back and measure each seam, to see what's causing the problem. If all else fails, I'd just make the pinwheel section a tad bigger, then trim it down to size.
Another reason for the problem, may be your HST seams. Some patterns assume you'll use a
scant 1/4" there. I never did like the scant 1/4" practice, as IMO the bias seams need more stability, not less. However, many people seem to think scant seams are the way to go.

LOL, I have always assumed the "scant" 1/4 inch seams are because they didn't do it right in the first place, not because of me. I have never heard of anything so silly in my life than when I started quilting and learned about "scant".