Puzzled about HSTs
 

I understand the rule of thumb if using two squares to make HSTs by sewing 1/4" on either side of a diagonal mark is to cut the squares 7/8" larger than the finished size of the HST block, or, like me, cut it a whole inch larger and then trim the HSTs to size. Can someone please explain how, when sewing two 5" charm squares by this method, I get 4-1/2" HSTs instead of the expected 4". I am truly puzzled! :o

Did you measure the charm squares first? Perhaps they were bigger than 5"?

You sew straight and a nice 1/4 seam. The extra is allowed for those of us who have trouble doing one or the other of those two items. A quilt pattern publisher I have followed only cuts 3/8" larger. Now that is no leeway - I had to scrap a few when I tried it her way.

Your 1/4" seam is removing 1/2" of fabric whether it's a straight or diagonal seam so you 4 1/2" is understandable.

As you said, you start with 7/8" larger than the FINISHED size of the HST. You ended up with 4 1/2" HST which will be 4" when they are FINISHED. So it worked!! :o)

I read your question to mean that your HST's were 4.5" finished, not unfinished. The only way for that to happen is that the fabric was too large to begin with. I hadn't thought about krafty's explanation - was that the problem?

Dunster, as the pattern called for, I started with 5" charms and the HSTs finished at 4-1/2". I sewed with a scant 1/4" seam as directed and the HSTs turned out fine, with just a smidge trimmed off. So now I'm inclined to go with Irishrose's explanation that pattern creators and quilting instructors use the 7/8" addition as a cushion. Now, if I'm in a pinch and need a few extra inches of fabric when making HSTs, I will keep this in mind and cut the pieces with less than the 7/8" allowance asked for -- and making sure I sew the seams extra carefully. :) I love learning something new every day! Thanks.

No, I can assure you that the 7/8" is not padded at all. When you say that they "finished" at 4.5" do you really mean that they measured 4.5" with the raw edges showing? That would mean that they actually FINISHED at 4" (or a shade larger if you didn't trim), as expected.

I learned something about the word 'finished'. I had originally thought that it was the size prior to sewing, with 1/4" all around not taken into the math equation.

Learning a lot of stuff on this board. :)

"Finished" means the size the blocks will be once in a completed quilt. So, if you have a 12.5" block, it will measure 12.5" to start, 12.25" when you have a neighboring block sewn to it, and 12" when all neighboring blocks/borders/sashing is sewn to it. 12" is the "finished" size.

Senior moment? We all have them. Even those who are not yet seniors. I've even had senior weeks. :) Glad it's all straightened out.