Could someone explain something to me, please?
05-23-2012, 10:03 AM
#13
Power Poster
Join Date: Mar 2009
Posts: 15,639
Your piece of fabric has two directions: width and length. In case of a square, these dimensions are the same.
Let's use a rectangle as an example, maybe that will make more sense. Let's say the size of the fabric rectangle is 3" by 5" - Now you sew another rectangle to the first one along the 5" measurement. You will use 1/4" seam on BOTH pieces and both rectangles will be 2 3/4" x 5". Sew another rectangle to the bottom and now your center piece will be 2 1/2" x 5" (Notice how the 5" measurement has not changed yet).
Now imagine that you sew a 3" x 5" piece to the end. This will leave each piece at 3" x 4 3/4" Sew the other piece to the other end and your center patch will be 3" x 4 1/2" (Notice how the 3" measurement hasn't changed)
If you sew pieces all around then you will use up 1/4" on the top, and 1/4" on the bottom (and this measurement will be subtracted from the height). Then you will use up 1/4" on the left side and 1/4" from the right side (and this measurement will be subtracted from the width).
Let's use a rectangle as an example, maybe that will make more sense. Let's say the size of the fabric rectangle is 3" by 5" - Now you sew another rectangle to the first one along the 5" measurement. You will use 1/4" seam on BOTH pieces and both rectangles will be 2 3/4" x 5". Sew another rectangle to the bottom and now your center piece will be 2 1/2" x 5" (Notice how the 5" measurement has not changed yet).
Now imagine that you sew a 3" x 5" piece to the end. This will leave each piece at 3" x 4 3/4" Sew the other piece to the other end and your center patch will be 3" x 4 1/2" (Notice how the 3" measurement hasn't changed)
If you sew pieces all around then you will use up 1/4" on the top, and 1/4" on the bottom (and this measurement will be subtracted from the height). Then you will use up 1/4" on the left side and 1/4" from the right side (and this measurement will be subtracted from the width).
05-24-2012, 03:34 AM
#16
Super Member
Join Date: Apr 2011
Location: Vermont
Posts: 1,095
Think of it this way, a 3.5 in square is that measurement ACROSS the square, not 3.5 across plus 3.5 top to bottom, so you only take off the quarter inch seam two times, because that is what affects the measurement across the square. Does that help? Your plan for a cheat sheet is a good one. I copied one from a magazine a long time ago and it lives by my machine.
05-24-2012, 04:55 AM
#17
Super Member
Join Date: Jan 2009
Posts: 4,688
but I just can't get my head around the reasoning (tell ya, I'm not good at math reasoning) if I taking a 1/4 inch off each side (1/2 " total for width and 1/2" total for length) that still gives me 1" taken off for seam allowances. why isn't that calculated- for 1/2 off width + 1/2 off length = 1").
If you consider both directions (length and width) for one element (the seam allowances), you have to do it for the other as well (the square sides).
Last edited by ghostrider; 05-24-2012 at 05:03 AM.
05-24-2012, 05:10 AM
#18
Junior Member
Join Date: Nov 2011
Location: south of Houston, TX
Posts: 186
I understand the math, and I understand the confusion. Sometimes you just have to believe and take that leap of faith and cut the way the other quilters say to cut. Understanding will come when you cut and sew. In my case, understanding comes slowly....thank you patient quilting community!
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