Friday, November 25, 2016

Making a Quilt at Half (Or Any Other) Scale

My version of Bonnie Hunter's pattern,
Allietare, features a reduced number
of blocks, all made at half scale,
to create a nicely sized wall hanging.
Have you ever loved a quilt pattern, but you just didn't want to tackle another big project? Fortunately, there are a few different ways to resize a quilt. We can...
  • Change the number of blocks
  • Change the size of the sashing &/or border(s)
  • Change the scale of the quilt
The first two methods are picked up by many quilters pretty easily, but people often hesitate when it comes to changing the scale of their blocks, especially if they feel math challenged. However, the calculation is pretty straight forward once you get the hang of it. Changing the scale of a quilt also offers some advantages, such as retaining the full effect of the pattern (something that can be lost when you reduce the number of blocks), and using half the yardage and being faster to make than the original pattern.

Since people most frequently seem interested in reducing the scale of their blocks to make a smaller quilt, rather than enlarging it, that’s what I’ll focus on here. When reducing, it’s often easiest to reduce the scale by half. You can reduce by other amounts, but you may need to take into account the underlying grid the block is made on (9-patch, 4x4, etc.) &/or be willing to work with 16ths of an inch (or smaller!) or odd sizes like 2.438”.

Here are the basic steps to change the scale of your quilt.

 1)  Determine your multiplier. Take the new size that you want your quilt to be and divide it by the size of the original quilt. Sometimes you don’t need to do any math for this. If you know you want the new quilt to be half scale, then your multiplier is 0.5 (this is the multiplier I’ll use in my examples). If you want the new quilt to be twice as large, then the multiplier would be 2.


2)  Determine the cut size of the patch in the original pattern.

3)  Subtract the seam allowance from the cut size to determine the finished size of the original patch.

4)  Multiply the original finished size from Step 3 with the multiplier from Step 1. This will be the finished size of your new patch.

5)  Add the appropriate seam allowance (1/2” for squares and rectangles, 7/8” for HSTs, or 1-1/4” for QSTs) to your new finished patch size to find the new size you need to cut.


Examples:
Cutting squares at half scale
Original cut patch = 2-1/2” x 2-1/2”
Subtract the 1/2” seam allowance = 2” x 2” finished original patch
Use the multiplier: 2” x 0.5 = 1” x 1” new patch
Add 1/2” seam allowance = 1-1/2” x 1-1/2” new cut size

Cutting rectangles at half scale
Original cut patch = 2-1/2” x 4-1/2”
Subtract the 1/2” seam allowance = 2” x 4” finished original patch
Use the multiplier: 2” x 0.5 = 1” and 4” x 0.5 = 2” gives a 1” x 2” new patch
Add 1/2” seam allowance = 1-1/2” x 2-1/2” new cut size

Cutting HSTs at half scale (This assumes we’re cutting squares, and then cutting them once diagonally to make our HSTs.)
Original cut patch = 3-7/8” x 3-7/8”
Subtract the 7/8” seam allowance = 3” x 3” finished original patch
Use the multiplier: 3” x 0.5 = 1-1/2” x 1-1/2”
Add 7/8” seam allowance = 2-3/8” x 2-3/8” new cut size

If you’re using a specialty ruler, such as the Easy Angle or Fons & Porter Half and Quarter ruler, to cut HSTs from strips, then calculate the new strip width by subtracting and then adding a 1/2” seam allowance (as with the squares), rather than a 7/8” seam allowance.
(Example: Using a specialty ruler, you can use a strip 3-1/2" wide to cut HSTs that will finish at 3". At half scale, the HSTs will finish at 1-1/2" and will be cut from a strip 2" wide.)

Cutting QSTs at half scale (This assumes we’re cutting squares, and then cutting them twice diagonally to make our QSTs.)
Original cut patch = 5-1/4” x 5-1/4”
Subtract the 1-1/4” seam allowance = 4” x 4” finished original patch
Use the multiplier: 4” x 0.5 = 2” x 2”
Add 1-1/4” seam allowance = 3-1/4” x 3-1/4” new cut size

If you’re using a specialty ruler, such as the Companion Angle or Fons & Porter Half and Quarter ruler, to cut QSTs from strips, then calculate the new strip width by subtracting and then adding a 1/2” seam allowance (as with the squares), rather than a 1-1/4” seam allowance.
(Example: Using a specialty ruler, you can use a strip 4-1/2" wide to cut QSTs that will finish at 4". At half scale, the QSTs will finish at 2" and will be cut from a strip 2-1/2" wide.)

You can use this same calculation to determine unit sizes. For instance, if your pattern has a 4-patch unit with a trim size of 3-1/2” x 3-1/2”, then it will finish at 3” x 3”. The half scale 4-patch will have a finished size of 1-1/2” x 1-1/2”, and should be trimmed at 2”x 2”.

Here are some at-a-glance tables for making half scale units.
(All sizes in inches)

-Happy sewing!

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