by Karen Johnson
The key to this method is pre-sewing your strips together. We’ll also use this ruler to make the three-color pinwheel you see in our Pinwheel graphic.
Pros: No worrying about raw bias edges – they are sewn in before you handle them! You can make a bunch of HSTs without stopping. You don’t need a magic formula or do any math. The ruler is long enough that you don’t need any other rulers to cut your strips in preparation.
Cons: As with any specialty ruler, unless you use it often, you’ll forget how and it takes a few minutes of orienting yourself before you begin.
Note, don’t try to make any of these steps using a regular ruler. You have to trust the pre-marked lines on the Wonder Cut Ruler. If you try to transfer the logic to a regular ruler, you’ll have a mess…trust us, we tried!
Decide what size you want your unfinished HSTs to be. Unfinished means the triangles are assembled into a square block, but not yet sewn into a quilt, so there are 4 raw edges to your square block. In our example, we want 3 1/2" finished, so we need 4" unfinished.
Using the long edge of the Wonder Cut Ruler, cut a strip of fabric 4" wide. Note the marking on the ruler that says “Cut on This Edge”. If you cut both of your contrasting colors at once, layer them RST to save you a step later.
Sew the strip, like a tube, 1/4" seam allowance on each side, as shown.
Place the Wonder Cut Ruler on the strip, using the diagonal lines on the ruler. Position the 4" mark on one side of the tube. Note, the tip of the ruler will just come to the other seam and will not reach the edge of the fabric. Cut on both sides of the ruler to form a triangle. Reposition the ruler to the opposite side of the strip. Again, align the diagonal 4" mark along the long edge of your strip, but this time, align one side of the ruler to the cut edge of the tube. Cut the other side of the triangle. Continue with this method cutting the entire tube. With this size block, you’ll get 18 HSTs out of the entire width of fabric! Note, after you cut the first two HSTs, the third one will be pre-trimmed on one corner (an extra bonus)
Unfold each square, but watch for a tiny bit of stitching in the tips – if your cut wasn’t a perfect 4", or your seams weren’t perfect 1/4" seams, you might have a couple of stitches in your tips. No worries! Just gently remove the stitches with a seam ripper (or even just your fingernails). Gently press the seam allowance to the darker fabric. Cool, huh?
Look closely at this block. The yellow and pink triangles form another triangle, but it’s not a HST because the short sides of the triangle are joined, instead of the long sides. Now look at the portion of the block that has all three colors in it…that is a HST! The Wonder Cut Ruler has a terrific shortcut for creating the three-color, three-triangle version of this HST.
We’re going to make a 9" finished block. To make a 9" finished block, you’ll need to make four smaller units. This smaller unit will be 5" unfinished three-color HSTs. Using the Wonder Cut Ruler horizontal lines, find the 5" line and cut three strips, one from each of the three colors of fabric. We used dark purple, pink, and yellow. Remember, don’t use your regular rulers for this part! Only use the Wonder Cut Ruler.
Set aside the dark purple (or the color you will be using for the largest triangle). Take the remaining two strips, place them RST and sew 1/4" seam allowance down the entire length. Only do this on one side. Square up one end of the strip to remove the selvage.
Using the Wonder Cut Ruler, cut the long strip into pieces using the 5" horizontal line – be sure to use the straight side of the tool, not the diagonal, and cut on the side that says Cut Along This Edge.
Cut the whole piece up, press each seam allowance to the darker fabric. Sew them together, end to end, to create a 2 color checkerboard. Press the remaining seams to the darker fabric.
Lay the checkerboard strip RST with the dark purple strip that you set aside. Stitch the entire length of the strip 1/4" seam allowance, down both sides.
Cut the HSTs using the Wonder Cut Ruler, as you did in Method Four, except this time, center the diagonal side of the ruler on the checkboard seam before you cut. See the extra line on the diagonal side, just for this? Cut both sides of the triangle. Reposition the Wonder Cut Ruler to the opposite side, again centering on the center of the checkerboard seam. Cut both sides of the triangle, discarding the little bit of waste.
For our pinwheel block, make four of these units. Press the seam allowance to the darker fabric. You now have the four units you need to make a three-color pinwheel! Refer to lesson one for tips on piecing these together for perfect points.