Originally Posted by
Feathers-N-Fur
I would cut the panel to 30.5x40.5, then make the blocks 10.5. This gives you a finished 30x40 in the middle and 10 in blocks. Makes it simple to make the final quilt size whatever you want.
You just created another problem though. Churn dash blocks are a 9 patch block and 10.5 does not divide evenly by 3. I would make the blocks either 6 or 9 inches and then use sashing strips to make the blocks work with the panel.