Let's Talk About Grids
- It's easy to change a patchwork quilt block's finished size by altering the size of each grid in the block.
- Finished sizes of block grids needn't be in whole numbers. Use fractions if you like, as long as they are dimensions you can cut with a rotary cutter (if not, plan to construct your block with templates).
- When considering block size determine finished sizes first.
The most simple quilt block to scale up or down is a block made up of only squares of fabric, left illustration, and for a nine-patch block, any finished block size will work as long as it's divisible by three (the grid of three blocks across and down). For instance, finished sizes that are possible include:
- a 15" block, with nine squares that finish at 5" x 5" each
- a 12" block, with nine squares that finish at 4" x 4" each
- a 9" block, with nine squares that finish at 3" x 3" each
- a 7-1/2" block, with nine squares that finish at 2-1/2" x 2-1/2" each
- a 6" block, with nine squares that finish at 2" x 2" each
Notice that squares do not have to finish in even numbers -- any number that is rotary cuttable will work just fine.
Changing the Size of Fussier Quilt BlocksThere may be times you choose to make quilt blocks only from squares, but most of your blocks will be a bit more intricate, and sizing them up or down will require a few extra considerations.
Let's look at the nine-patch block on the right. It's made up of nine grids, but only two of those grids are simple squares. Four are half-square triangle units and three are smaller nine-patch units.
Always consider the grids containing the smallest patches when you choose a finished block size.
Could the design be made into a 15" block that's rotary cuttable?
- The grids with small nine-patches would finish at 5" square in that scenario. Dividing 5" (the grid size) by 3 (the number of squares across and down in the small units) equals 1.66", a dimension that can't be cut accurately with a rotary ruler.
But let's say you need a quilt block that finishes at about 15".
- Use 1-3/4" (finished) squares in those units instead of the 1.66" required for a 15" block. The result (1-3/4" x 3) would produce a 5-1/4" (finished) grid.
- Multiply 5-1/4" by three (to account for all grids in the block, which must be equal) and you'll have quilt blocks that finish at 15-3/4", a perfectly acceptable size unless the blocks must match 15" neighbors.
How would you cut patchwork for a 15-3/4" finished quilt block?
- Four half-square triangles: cut (2) 6-1/8" x 6-1/8" dark squares and the same number and size of light squares - cut in half once diagonally; or leave the squares as-is and use the easy sandwich method to create the units.
- Two large squares: cut (2) 5-3/4" x 5-3/4" squares.
- Three small nine-patch units: cut (15) 2-1/4" x 2-1/4" dark squares and (12) 2-1/4" x 2-1/4" light squares (assuming you will not strip-piece the small nine patch units).
Read the pattern for the quilt block, called California Crossroads, to learn how a 13-1/2" (finished) block is cut and assembled.