8 1/2" Nine Patch Block
 

Hi,

Can anyone tell me what size blocks I would need to make a finished 8 1/2" nine patch block. If possible I will try to use strips, but I can't figure out what the width of the strips need to be to get a finished 8 1/2" block after sewn together.

The closest I came up with was 3 inch strips, three sewn together would give me a finished 8" block, I am not sure that is correct.

I think 3-3' would give you a 71/2 "....3- 3 1/2" would give you 9"...3 - 3 1/4 would give you 8 1/4. Soooo ....maybe 3 3/8????


I might do the 3 1/2 and trim????

3 5/16 is what EQ7 says. Make a test one first to be sure.

Each strip would need to be 3.3333 inch. If I calculated correctly. 8.5 plus .25 time 2 for each block equals 10 inches.
10 divided by 3 equals 3.33333333333333333333333333

Just do 3.33333333 and sew a scant bigger seam

Trimming would make only the outside squares smaller

3 1/3 is correct, but are you sure you want the block to be 8.5" finished? You mentioned that you thought three 3" strips would give you 8" finished, but that's incorrect; each 3" strip would be 2.5" finished, so you would get a 7.5" finished block, 8" unfinished.

For any FINISHED block size, if you want a 9-patch you need to divide the FINISHED block size by 3, then add 1/2 to get the strip size. Conversely, for any strip size, subtract 1/2 and then multiply by 3 to get the FINISHED 9-patch block size. For instance, for an 9" FINISHED block you need to divide 9 by 3 (giving 3) and add 1/2 (giving 3 1/2).

8.5 is a very unusual size for a finished block. Nothing really goes into 8.5 very nicely. If you look at Marcia Hohn's Quilter's Cache site, you won't see any blocks that are 8.5".

Don't sew a bigger seam, because you really do want the strips to be exactly 3 1/3 inches, using 1/4" seams, to get a block that is 8.5" finished.

This was IMMENSLY helpful and timely for me! Thank you all, especially dunster! The reason I require the oddball 8.5" finished nine-patch block, is that I'm cutting multiple fat quarters into four 9" square blocks which will be alternated with nine-patch blocks to make a patchwork-looking picnic blanket. Thanks to you all...

Dunster - thank you so much. I am a little rusty in my 'quilter's math' and that last block I made, I had to draw it out to make sure that I had the correct block size for a donation block. I was thinking of making some 9 patches next and your directions were very timely :)

Sylvia

3.333333333333333333333333333333333333333" which includes you seams. Why not go to 9"

8.5 divided by 3 equals 2.83333333333333333333333 plus a half inch for two seam allowances makes 3.3333333333333. Which requires a 1/4" seam allowance all around. Any more or less and you won't get near 8.5"

You can't divide 8.5 by 3 and get any number that is a 16th of anything..5/16 is close to .333333333333 but it's not--it's 3.125

If you are making a picnic blanket I am wondering why you need the 8.5" block. It appears to me that you would be easier to alter the large block cut from the fat quarter rather than all those very odd size smaller squares for your 9 patch. For me it would be too much aggrivation to deal with an odd size smaller square and more precision to get it exact. More flexibility in the larger squares and considering all fat quarter are not the same size.

Good point. What I've seen, FQ's are in the neighborhood of 18". Generally a bit less. I'd be tempted to cut 6 7" squares, add a bit of a sash and then make the 9 patch 9". Or even go to 6"

Or cut 3" strips to end up with 7.5 finished and then cut the FQ's to 8".

I would cut a piece of paper to 8.5" square, and fold it into thirds. Then mark that fold, and put it under my ruler, to get an idea where it would fall . . ..

The math way is the way to go, for sure. but I would need a way to visualize that perfect cut.

good luck!!

Formula: finished block size divided by 3 and add 1/2" for seam allowances = 8 1/2" nine patch blocks