Thanks to all for the great ideas. I'll make the most and be thankful it's not my exchange HSTs that are wonky....

Wendy

Wendy, I would size all of them down to 4.25". Use the 2-1/8" mark on the ruler to be at the center point and your corners will then be where they are supposed to be! Or, do log cabin strips (2") around each pinwheel and then cut to uniform size. Looks cute if you cut the outer squares off kilter, then you pinwheels will all be tilted and look like thy are spinning. Play, have fun, enjoy. Some of our "mistakes" come out to be really neat learning experiences and great designs! Bev

Wendy,
Something I learned the hard way in my Apparel Construction Course is that fusible interfacing can shrink. Perhaps the designer of this product had a good idea in the development of their product. Using a fusible keeps the sewing and cutting lines from moving around while you sew the HSTs. Unfortunately the fusible interfacing may not stay the same size as intended onced the heat is applied. If you still want to use the fused HSTs, my best advice is to recut them to be all the same size based on the smallest HST. When all is said and done, the front of the HSTs will be the side you see and no one has to know they started out another size. Enjoy the pretty side.

I have no idea how you would use a fusible for HSTs, but think that you may be able to tell that sewing with foundation papers on the bias of the fabric minimized distortion when you are sewing any triangles. In fact, any time that you can stitch on the bias BEFORE the seam allowance is trimmed, your fabric will be more stable than stitching a bias seam with only 1/4" seam allowance beside the stitching line.

If you are not using foundation papers, I highly recommend starching your fabric before you cut your squares (or triangles) to size. After the fabric is dry and pressed flat, then cut your shapes and stitch.

And it's always important to be aware of exactly where your seam needs to be sewn. If you aren't sure that you are stitching an accurate 1/4" seam allowance you might want to check my tutorial here: http://good-times.webshots.com/album/569415726bHNKHF

You might also be interested in my pinwheel tute from an earlier BOM here: http://entertainment.webshots.com/album/570305305PZwEyD

Or...you can always plan to make your pieces larger than the finished size and trim them down after the seam is sewn

I have never seen the fusible HST so couldn't guess as to what happened. For me I am using Thangles for the friendship exchange and it is sewing acurately. But if it hadn't then I would have sewn just slightly on the seam allowance side of the line and trimmed to the correct size. That being said you have quite a difference of 1/4 inch and I am assuming you are following a line. I'm wondering if the fusible was printed accurately. I wouldn't think that fusible would be as reliable simply because it isn't as stable as paper also paper you tear away and the fusible would have to stay on the HST. That might take away some of your measurement along with the thread. I like to use a thinner thread when piecing. It helps to make things more accurate. Just guessing and thinking out loud. or more to the point typing out loud .

I can't offer tips but sure can use some. Early in the exchange I used a fusible marked with sewing lines to make four sets of HSTs. Since these might have been inconsistent with the paper guides - I kept them for a twin sized quilt.

My results have been "off" even within the fused HSTs. (I suppose I have one tip - paper is better than fusible for HSTs! The fusible is slippery.) I've made them all into pinwheels and plan to use sashing to join them. The challenge is that the pinwheels measure between 4.25 and 4.5 inches in size. (4.5 is the "correct" size.) Of course, some opportunities to correct for this are now gone... Since all of us will be working with HSTs - maybe my troubles can solicit tips that will benefit us newbies.

Obviously, being more precise from the get go is my lesson learned. But - given where I am - any recommendations for dealing with this are welcome.

What are the merits of:
1 - Cutting each square to 4.25" (knowing the outer points won't fall in the corners...)
2 - Trying to press (block) the squares to reach 4.5"
3 - using the seam allowances to adjust
4 - tossing out the smaller squares

Thanks in advance for your help! (For those of you who may be worrying about the quality of my HSTs for the exchange - know that I did a lot better with Edyta's paper and stayed on the line! Just can't stand to toss these wonky babies...)
Wendy