One question that seems to constantly come up with quilters is how do I know what size square of fabric to start with to end with a certain size square when I sew the triangles back together. Basically they want to take a beginning square - divide it in half diagonally - then sew it back together to come up with another sewn square, smaller in size than the beginning square. The problem comes in when you want to end with a certain size sewn square, let's say 2.5 inches (unfinished and so including a 1/4" allowance for a 2" finished square). How do you figure out how large the first square of fabric should be?
I presented my husband with this problem and being the persistent person he is, he came up with this approximation of the formula:
The formula to approximate the half square triangle is:
A = a + 3/8 inch, where A is the beginning square of fabric and a is the ending sewn squareOr
Beginning square of fabric = Desired Ending Sewn Square + 3/8 inchIf you are curious, the more accurate version of the formula is:
A = a + (√2 x .25)So, for our problem of how large a square to start with if I want an ending square of 2.5 inches,
A = a + 3/8
A = 2 1/2 + 3/8
A = 2 4/8 +3/8 (converting to eighths)
A =2 7/8 inches
I picked up this 1949 Singer sewing machine this week. I can't wait to test drive it! It has the original instructions, lots of feet, and a buttonholer also with instructions. I've always wanted one of these, but never wanted to put out the cash for it. Then I saw this for a pretty good price and snatched it up!
Here is the book cover I created with my block made from the Sumptuous Starts Round Robin. I just love how it turned out. There were four lovely ladies, Arlene, Ann, Skye, and Kathy, who all added stitching. It is even prettier in person.
