AngelinaMaria

I've been searching to find this out and can't find a reference anywhere. Anyway, I need to end up with a block 8.5 inches in size. I will be making an hourglass out of 2 fabrics and will place the fabrics together correct sides together and sew diagonally on each side of the diagonal line then cut and match the opposite pieces together to form the hourglass. What size do I need to cut my 2 squares to arrive at a 8.5 hourglass--I always like to have about 1/4 inch to trim to make a perfectly sized block.

Krisb

When you say finished block, are you including the seam allowance? So the ending size of the block is 8"? If yes, the technically "correct" starting measurement for the squares is 9 1/4". To leave some extra to square up the blocks , start with 9 1/2. In other words, start with squares 1 1/2" larger than the finished size of your block, finished size excluding seam allowances to sew the blocks to each other.


Here's a link to a calculator

http://www.patchwork-and-quilting.co...triangles.html

Jan in VA

Cut your plain squares at 9.5"
You will trim the block segment after you have completely sewn it into an hourglass so that it is 8.5".

Jan in VA

deemail

according to the 'magic number theory... the 8.5 (fin size...you said, so we're working with that.. after this, state 8" finished or 8.5 cut or 9 cut...whatever 'ending up with a block' still doesn't tell us if that is cut or finished)...anyway... you said 8.5 ...so add 1.25 and that gives you 9.75... which is a pain to cut...cut them 10, do your sewing and then you will have a tiny bit to trim when you square up and they will all be perfect...i NEVER mess with the weird little numbers.... tons of stuff want you to add 7/8 of an inch.... good grief! add an inch...who has time to add in units of 7/8s? Remember, when you square up hourglasses, you place the correct spot on your ruler on the middle intersection not on any corner references...otherwise your hourglass may be the correct size but it will be off center....