Originally Posted by
bearisgray
even though I think I cut "exactly" - when I measure my 2-1/2 inch strip - it is actually about 2-9/32 inches wide - about a rotary blade's thickness wider than the template.
the fabric has to turn and accommodate the thread - and the result would be less than 4.5 inches
I think the place to start is to measure the size of one's cut pieces. A couple of threads here and there can make a difference in the finished size of the unit.
2 9/32 inch is actually closer to 2 1/4 inch. If you are working with 2 1/2 inches, that is 2 16/32 inches. So a 32nd inch larger is 2 17/32.
You would think thread doesn't take up any space, but look how it piles up on a spool. And folding takes a little space, too. I aim for pieces a little larger and trim segments of the block as they are made. If I'm making a 12 1/2 in. pin wheel, I need 4 HSTs. After they are sewn, I trim them to exactly 4 1/2 inches. Then one more seam each way, and I have a 12 1/2 inch block.
Trimming smaller segments of the block makes things come together accurately.
I know some of you can do your seams perfectly the first time, but not this chick.