cminor

I feel like I should be understanding this more - I have had way too many posts regarding math.

I have the Fons & Porter half and qtr square ruler. I love it and used in in my last quilt - which turned out really well. I am thinking I want to do a Jacob's ladder quilt - but again - just don't get the math. If I want a big block - lets say 18 inches finished - how does my math work out? Or would it make more sense with this ruler that I make it a different size?

Thanks so much - I don't know people quilted before this board?? :)

ontheriver

I'm the same, I don't do math. Maybe because I hate it. I do the least I can and if I have a question, I ask.

MTS

You have to break the block down into a grid pattern, and you have to learn how to recognize it.

The JL block is on a 3x3 grid. Like a 9Patch, but each of the patches is actually a pieced unit.

For a JL, you need five 4-patch blocks and four HST blocks.

Based on a finished 18" block, each grid unit will be 6" finished.

FOUR PATCH Block
So you need to make the 4patch blocks each finish at 6".
How big would each square be in that block?
3" finished.
So the squares (or strips) would be cut 3.5" wide - one light, one dark.
Sew the two strips together, then crosscut into 3.5 subunits, then blah, blah, blah.


HST Block
They also have to finish at 6".
The "exact" method is to add 7/8" to the finished size.
I prefer to add 1.25" and trim down.
So you would need 2 light and 2 dark squares - each 7.25" square.
Draw a diagonal line on the back of the lighter square, right sides together, sew 1/4" on each side of the line, cut, blah, blah, blah.

You either work your way down from the finished size of the whole block, or up from the smallest unit's size.

debcavan

If you have a certain sized block and your patterns has four equal blocks up the side and across, then you would divide 18" by 4 and be sure to add the seam allowances. If it is 5 equal squares up the side and across the block, you would divide by 5 and add the seam allowances. The same way with six equal squares or what ever number

If I have a nine patch and I want a 6 inch finished square, I know I have 3 squares going up and 3 across. So each square is 2" finished and I would have to cute 2 1/2 because of seam allowances. If I want to go up to a 9 inch square. 9 divided by 3 squares is 3 then add the seam allowances. It works the same for any block.

You always design with the finished sizes and add the seam allowances.

If I want to find the size of the half square triangles in a square, I make the finished size of the square out of cardboard. Cut it in half and add seam allowances on all three sides. Then I find the right line to cut on my ruler by putting my cardboard on my ruler, the one that had the seam allowances added on all three sides.

Way back they folded paper to find the correct sizes..

QuiltE

CMinor ... watch when you are in stores for the books that have charts for these things. I have a couple that shows how to do the math, as well as giving you the yardages needed.

eg. one chart is for the HSTs you need for this ... you can look up the size and # needed, and it'll tell you the yardage required. Like MTS, I usually make mine bigger and trim for precision after all the sewing is done, so make sure you calculate accordingly!!

Mine also has charts for the variables of the B .... borders, blocks, binding, backings ... and the yardages required. It;s a great help and I grab it frequently.

Mazda

I need too watch this topic!

cminor

MTS is the best! That was where I got my info on the 2nd part of my pink ribbon quilt. Again - that is why I love love love this board!

I never thought to look for books. That is a great idea.

Thank you for your help!

Ramona Byrd

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Me too. So I always make sure I have enough left over for something or other. You can always make something with scraps, right?