http://www.allthingsfrugal.com/pinwheel.htm

This site really helped me get my pinwheels to look much better. Not perfect, but usable.

Thank-you so much for the sample pic and for not being afraid to ask about your mistakes...I learned a couple things from all the wonderful responses.
yep still learning.

I think you do need to pin.

If the last seam you sewed was the up-down one in the picture, then just sewing over this seam taking up more seam allowance should fix this problem. When you are making a seam deeper, you can just sew again -- no need to rip out the first one.

If the last seam you sewed was the left-right one, then it looks to me as if your seam allowance was too small when you sewed the two half-square triangle blocks together. You would have to rip out the last seam, then re-sew the remaining two seams with a wider seam allowance.

Also, it looks as if these blocks got a lot of handling. Starching before cutting and/or starching when ironing seams should help prevent the pieces from being stretched out of shape.

Over the weekend I picked up a little magnet gadget that sits right next to your machines needle after you measure from the needle what size seam you want, I am hoping this helps w/ my scant 1/4 seams. I have a older kenmore so its not computerized, I would be leery to to use any magnet on a computerized machine, I have heard both ok to use & not ok to use...not sure.

it looks like the fabric wasn't cut on grain and the edges got a little stretched out.
then where the hst came together to make points, that 1/4" went missing because of the stretching.

i always get into trouble if i do not square up each square before sewing it into a block. Try this. If i square up to 3 or 3 1/2 inch, or whatever to make them all even, they will be matching up.

I do the same thing Prism.

Hello What is a scant 1/4 inch?

Go to the tutorial section of this board - there is a tutorial or 2 about how to make these.