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12-19-2011, 01:08 PM
#8
MTS
Banned

Join Date: Nov 2010
Posts: 4,134

Originally Posted by LucyInTheSky
I'm confuzzled... wouldn't the distance from the top point to bottom be 6 1/2" (or maybe 6, without the seam allowance?) If I'm doing a big square and adding squares to the sides for the triangles (a la snowball method), wouldn't I need it 6 1/2"? I know the finished sides will be 6 / sqrt (2), but I don't plan to cut it as a diamond.

The square in your diagram is ON POINT - so the DIAGONAL of the square (point to point) is what would be be 6" FINISHED, not the sides of the square - they would need to be smaller.

How much smaller?
The relationship is 1.414.
For example, a 6" FINISHED block ON POINT will measure ~8.5" across FINISHED.
6" x 1.414 = 8.5"

For your block, you need to work backwards:

6" FINISHED block divided by 1.414 = a 4.25" SQUARE plus .5" SEAM ALLOWANCE = 4.75" starting square for the center of the block.

And if each side of the square is 4.25" FINISHED when it's on the DIAGONAL, then you'd need a 3" FINISHED square (3.5" UNFINISHED) square to use as the snowball.

4.25" divided by 1.414 = 3" FINISHED + .5" SEAM ALLOWANCE = 3.5" STARTING SNOWBALL Square.

Since you're going to be sewing ON the diagonal, you don't need the extra 3/8" for the seam allowance like you do for HST blocks (as there aren't 2 equal seam allowances to worry about).

There is a slight bit of rounding in the above calculations.

Too convoluted? Try this other option - no-waste Square-in-a-Square method:
http://www.hgtv.com/video/super-fast...deo/index.html

I'd test one out first, starting with 4.75" squares. If you aren't married to the 6" FINISHED - meaning you're not combining this block with different blocks - then you could start with ANY size you wanted. Charm packs of 5" squares would render a slightly larger FINISHED block, but not much at all. And that method makes the sewing a BREEZE!

Last edited by MTS; 12-19-2011 at 01:11 PM.