Pinwheel help
 

I need help. My mind just does not operate in mathematical mode. I want a 6 inch pinwheel in my quilt. I want to cut out 2 squares and sew around the perimeter and cut it corner to corner. There's probably a name for this but I don't know what it is. I tried cutting 6 1/2 inch squares but when I put the pinwheel together it was 7 5/8 inches square. It made it beautiful pinwheel but it's too big. How did this happen? What size do I cut my squares to get a 6 inch square? Am I making this too difficult?

I don't think you're making it too difficult but I can't help you with the math part. Sorry :(

i cut mine one inch larger, make them and then trim using the 45 degree line down the seam.
here is a sight.
http://www.quiltchat.com/lessons/halfsqr.html

does the 6" pinwheel mean with or without seam allowance?

Your 6-1/2" squares came out 7-5/8", so 1-1/8" larger than it started. Try cutting your squares 1-1/8" smaller than the size you want it. You can do it with paper and sew it so you don't waste fabric trying it out. If it is only a little big, I'd make them bigger and square the blocks down to the size you want. Be sure to starch your fabric before you cut - you'll have a lot of bias edges.

Eddie used that method a while back. I can't get his pics to open, but if you send him a message thru here or his blog, maybe he can provide more info.

http://www.quiltingboard.com/picture...lt-t27766.html

http://arkansasmanquilter.blogspot.com/search?q=fig

if you are cutting diagonally you need to divide the finished size by 1.414-then round up- so- if you want 6" pinwheel squares you could cut your squares- 4 1/4" (or 4 1/2" & trim to size)
6" divided by 1.414=4.24 this size when cut diagonally will give you 6" bias edges.

I never care if they come out a little bigger as I trim them down to the size needed. They come out perfect every time that way!

i did some+ very happy with them--felt i had more control of the end size------starched ++ made it so they were bigger than needed [i did it by sewing paper!!!!!] then cut them back using diagonal seam to get them square

Why don't you trim what you have down to the size you need and measure then add the seam allowance for cutting. That way no waste!!

I am in agreement on cutting HSTs 1" larger than the finished size I want. In theory, this gives me 1/8" for perfection in trimming. For a 6" (finished size) pinwheel, begin with 2 squares that are 4" for each color.