A friend wants me to make a quilt for her dd 16th birthday. We picked the block and the colors. She saw an on point layout and liked it.

My problem is how do I figure what size block to cut to make the corner and side blocks. the finished blocks are 12"

I made the first block last night.

Just so you know I did see the blocks that were on wrong and fixed them just didn't take a new pick.

Hope I don't mess this up never did an on point before

I have just been through the same scenario...eventally the penny dropped you use the same size square as your block BUT add additional seam allowances for the diagonal..now ask yourself how I know this....well after cutting ALL my setting triangles...I found out they were all too small as I forgot to ADD the seam allowance for the diagonal cut!! :cry:

Pretty block, its gonna be gorgeous!!

If the finished size of your block is 12", multiply 12 x 1.414. It's the square root of 2 and a geometry thing. That equals 16.968. Round up. I like to go up and make them oversized and trim later, so I would cut squares about 18". Obviously, you will get 4 triangles per square, so if you need 30 triangle for your quilt, you would cut 8 - 18" squares

Cut each square in quarters diagonally. That gives you a straight-of-the-grain hypotenuse for the edge of your quilt - VERY important for a non-wavy border.

For the corners, I usually just cut two squares in half diagonally - for this quilt, a 10" square would work fine.

After you sew your quilt together (you will do it in diagonal rows), you will use a long ruler and rotary cutter to trim off the excess triangle fabric. I actually like to leave a little more of the triangle fabric so I don't have to make my border meet the points perfectly, so I might trim at 1/2" or more instead of measuring and cutting 1/4" from the block points. That causes the blocks to "float" in the body of the quilt and prevents their points being cut off.

Hope that helps! :mrgreen:

Connie I'm sure glad you said you noticed the wrong spots cause I was just gonna rain on your parade! LOL. It amazes me that we can look and look and LOOK at a block and it seems right but as soon as you go to show it off, the mistake just jumps right out at you (and everybody else of course) :oops: good luck with your on point, that makes some blocks look more elegant to me and I think it's a good choice for your embroidered blocks. BTW how can you see thru the smoke? I know that machine must be glad to see you go to bed at night! Now if only the one that does the piecing and the one that does the quilting would work on their own all you'd have to do is choose fabric and cut!
You make me jealous, you turn them out so fast!
Keep 'em coming!

For the setting triangles, take the finished size of the block x 1.414, round to the nearest 1/8 and add 1.25. Cut your square that size and cut on the diagonal both directions giving you four quarter square triangles

Your example:
12 x 1.414 = 16.968, round to 17 + 1.25. cut your square 18.25 and cut on the diagonal both directions.

For the corner triangle:
take the finished size x 1.414 /2 + 7/8 cut in half on the diagonal

I printed this off from quiltville.com and have it hanging above my cutting table:

http://quiltville.com/onpointmathpf.html

Very, very useful. I printed it out also.

I thought you did those blocks that way on purpose. I was waiting to see it finished to see the overall design.

No matter what size block you use, you will cut your filler triangle that measurement plus 1/2"......you can trim down later. Make sure that the long side of the triangle is on the lengthwise grain to avoid stretching.

Oh, and make sure you iron your blocks after each and every seam.

Another point.....your left hand side in on sidewise.