I am doing a BOM that uses a focus fabric. The Blocks have a square in the center using the focus fabric. As this is a Oriental theme I choose a fabric with a Cranes. In order to best show off the Crane in the center square for the 1st BOM I need to change its size from 4.5 to 5 inches. That means I will have to change all the other measurements! Do I just increase everything by 1/2 inch? In this case the center is surrounded by triangles made from 3 inch squares. Do I just use 3 1/2 inch squares?

Do a trial run with scrap fabric, if your shooting for one size for all blocks, making all parts larger will make the whole block larger, What block on the BOM are you using? May have to reduce other elements to reach the size your looking for.
Call it design choice.:)

You can see the block I mean at www.persimmonquilts.com.Look for the link to the 2010 BOM.( Sorry not sure how to send a link). I've started late as I was looking for the right focus fabric. The block I am working on is the June one. As you can see the center focus one is 4 1/2 where I need to go 5. Then they attach triangles made from cutting a 3 inch square in half.

Beautiful Blocks!!!!
I would make a sample of the inner square by increasing each 1/2", then I would measure that square. According to that measurement, then you will need to calculate the outer pieces, so that the block measures 12 1/2" unfinished.
Looking at the rest of the blocks that they have posted, you will end up having to change each block.
Good Luck!

i would eliminate those four orange triangles immediately surrounding the focus fabric. i would make the focus fabric the size of that complete space, and then go directly into the little 'basket' shapes. your central fabric would have to be on point to end up with the same shape as the one that includes the orange triangles.

if you want to keep orange, or whatever color you're using, in the mix, then cut your focal fabric on point leaving enough space to frame it with a tiny border of
that color. go from there. you'll end up with an on point shape, as shown, with the same color combo rearranged to suit your desired size.

that way you don't have to do the math.

edit: i don't know if i explained that right. picture the orange center as a solid piece. picture your focus fabric the size you want it, but on point. now think of the focus fabric on top of the orange, centered. this way, you're only making 2 changes, both minor, imo. one is twirling the center. the other is changing the size slightly. you still end up with the same size middle with an orange surround. the september block also has an on point center. are you doing all the blocks or is this your chosen one for this challenge?

Thanks Butterflywing
Thanks that would work! I mean about having the focus fabric the whole 6 1/2 on point and the follwing the directions from there on. Yes I am doing them all! On the ones that have the 3 1/2 centers I'll just select a bit of the focus fabric without the crane . I don't need to have a crane in each center but in the ones that do I want to be able to see the entire crane and not have to cut off part of the wings etc. I really have to remind myself that I can do it as I wish and the directions are not written in stone. Thanks again.

Correct, Nothing in Stone!!:)