1) So, I want to make the following block for a swap (Sorta, these are NOT the colors I want to use, but easily identifiable colors) - It needs to finish at 12 1/2 inches (so when my partner uses in her quilt it will be 12 inches finished.

How do I cut each of the pieces? (I suck SOOOO bad at math!)

2) IF I were to make an entire quilt of this block, using charm squares, how big would the pinwheel blocks need to be?

Now that I think about, I'm sure theres a pattern for this block already on the internet somewhere...

hmmmmmm

cut the yellow blocks to 6-1/2 inches. the size of the finished triangle blocks, which you will need 8 of for the whole block need to be3-1/2" unfinished. I like to piece my half square triangles larger then trim down, so i would likely cut 4-1/2" squares,mark a line diagonally, sew 1/4" to each side of this line, then press and cut down. is that clear as mud?

6 1/2' to start for the yellow squares and 3 1/2" EACH for the pinwheel block.

When you sew the pinwheel blocks together you have 3.5+3.5 = 7 -.5 (seam allowance) = 6.5 Do that twice for each square.

To assemble: 6.5 (pinwheel block)+ 6.5 (plain block) = 13 - .5 (seam allowance) = 12.5

the plain blocks will be cut 3 1/2 and cut two blue two purple at 3 7/8 draw line diagonal and sew 1/4 inch on each side of line cut on line

When I use that method I add one inch to the finished dimension and cut my HSTs down and square them up. I find it too hard to maintain everything just perfectly when using the 7/8" method. So I would start with a 4" square for the HSTs

I made a "ruler" to help with this sort of block - just use the 3.5" lines to make a square.

http://www.3dquilt.me.uk/homepagefil...gTriangles.htm

Answer to #2. If you use charm squares, the yellow would be 5" cut and 4 1/2" finished. Then the 1/2 square triangles that make up the pinwheel square would finish at 2 1/4" each. You would need to cut the charm square down to 3 1/4 each or just sew the diagonal 1/4 each on each side and trim finished blocks to 2 3/4". You will have a lot of waste if you just use charm squares. If you use the charm squares whole for the pinwheels, measure you finished block and cut the yellow the same size.

Sorry about the puzzled look on my face but how does that add to a 12 1/2" block?

6 1/2 inch for the yellow squares 7inch squares of 2 colors placed right sides together, sew 1/4 inch seam around all 4 sides. Then cut from corner to corner both ways that will make the 4 squares for the pinwheel block, turn them to make the pinwheel block , sew together square up to 6 1/2 inches

Thanks Everyone!!

Here's the finished product:

Edited to add: it won't let me upload a pic right now. I'll try again later...