Cutting math resources

[Melissa T.]

I love my "Patchwork Minus Mathwork" by Linda Causee (which I believe has been revised and re-released by Jeanne Stauffer). It is a collection of charts to help plan a quilt and figure yardage without doing actual math. It includes things like how many 4" finished half square triangles you can get from 1/4, 1/2, 1 yard and so on (16, 48, 112 if you are dying to know). However, it doesn't include how many 60 degree triangles, at X height I can get from Y yardage.

So, 2 questions -
1-What's your favorite reference guide for cutting/yardage math?
2-The book has 60 degree diamond charts, so can I just divide the # of diamonds by 2 to get the number of 60 degree triangles it would make? In other words, if 1 yard makes 120, 2 3/4" finished 60 degree diamonds, does it make 240, 2 3/4" finished 60 degree triangles?

Hope this makes sense and thank you in advance for your thoughts.

[Nancy R.]

Hi Melissa -

I'm a math person so I do all of my calculations myself, so no book recommendations. But I can answer your question about the 60 deg triangles. First, you would multiply rather than divide to go from the number of diamonds to the number of triangles because a diamond is made of two triangles. And you can't just multiply the number of diamonds by two to get the number of triangles because the triangles will have an extra 1/2" of seam allowance missing in the diamonds. It also depends on how you are orienting the diamonds and triangles when doing the cutting. In general, when cutting 60 degree triangles, you cut a strip of fabric the height of the triangles, then cut the triangles along the length of the fabric, flipping the ruler up and down so that the triangles butt up against each other. Diamond, on the other hand, are often cut at an angle. So the diamond numbers might have little relationship to the triangle numbers.

I'm too lazy to do the calculations for you, but maybe someone else will have them.

[Melissa T.]

Oops! I did misspeak/type and meant multiply rather than divide (I did the math right but not the explanation.
Thanks so much for your response.

[Melissa T.]

I am no help; this is one of the biggest reasons I use EQ7, it does all the math for me.

If you aren't familiar, it's Electric Quilt 7, and they now have a sort of "lite" version of it called EQ Stitch; it's computer software and you can choose/create any quilt layout, blocks, etc, and even color it and it will tell you how much fabric is needed for that quilt. So...not specifically "how many triangles per yard of fabric" but will give you how much yardage you need for a given project, if that makes sense.

You could probably get it to do so by creating a One Patch quilt, set to the size of whatever piece of fabric you want to cut (so, for ex, 18" x 22" for a fat quarter) and then make the patches whatever size/shape you're wanting to end up with, and it will fill in. (I guess you'd have to count how many show up...).

Let me play with it a minute and see if I can get it to do what I"m trying to tell you, and if so, I'll come back and post how many 60* triangles of that size for a yard of fabric. Be right back.....

[Melissa T.]

hmm, it's a bit harder than I thought. The setting is based on how tall & wide the triangle is, not the angle of the cut, so I can't get exactly what you want.

Martingale has several cutting charts in their files on their blog; you might find something there (Shop Martingale), or possibly also at Moda Bake Shop. Hope you get it figured out!