You can easily make combination units from a half-square triangle quilt block and an un-pieced square by using the MadamSew Quarter Inch Patchwork Ruler…no measuring necessary!

If you have tried sewing these patchwork quilt block units by drawing a line from corner to corner and then trying to accurately sew ¼” from each line you’ll find this method will take the guesswork out. It’s fast and easy, allowing you to dive into your quilt project!

Though the instructions for sewing half-square triangles is in the Quarter Inch Patchwork Ruler Set (QIPS) online manual we are presenting them here as well so you don’t have to link to the manual at this point. But check out the manual for additional information when you have time so you can get the most out of this versatile tool. I will be using the 9” QIP in this tutorial.

For this project, we’ll be using three different fabrics, two to make the Half-Square Triangles and an additional one to complete/make the Combination Units.

You will need two different fabrics for this unit.

Normally, you will decide on what size half-square triangle units you want to make and cut your fabric squares ⅜” - ½” larger.

Special NOTE: Because we will be using these half-square triangles in our combination units, cut your squares ¾” larger than you want your finished combination units to be.

You will need one square in each color fabric. I’m making mine with 6” squares.

Next, Follow the steps below to make your Half-Square Triangle Units.

Place the lighter of the two squares on your work surface, with the wrong side facing up.

Place the QIP ruler on the square with the middle line running through opposite corners on the diagonal. Using a sharp marking pen or pencil, draw a line on both sides of the ruler. These will be your sewing lines.

Place your lighter square on your darker square with the right sides together. Pin/clip if needed.

Using a straight stitch, sew on the edge of both marked lines closest to the middle. Trim your thread tails.

Using a cutting ruler and rotary cutter (I like using the 45mm rotary cutter), not the QIP, cut down the middle between the two sewn lines to make your half-square triangles. For ease of the remainder of the steps, I’m also using the MadamSew Self-Healing Rotating Cutting Mat so that I don’t have to walk around my work space or contort when I need to turn my unit around for a step.

Carefully press each unit toward the darker side if you can. Or press open. For this step, I love using the Wool Pressing Mat to get a nice, crisp press.

Cut off the little tails from each unit and square up your half-square triangles.

You will end up with two half-square triangle units. Remember, I started with two 6” square pieces of fabric and my units are now each 5 ⅝” square. This size difference is because adding the seams makes the squares smaller.

You are halfway there! Follow the next set of instructions and before long, you will have two completed Combination Square Units!

To make combination quilt block units, you will need one half-square triangle and one fabric square of equal size. (Because my Half-Square Triangle Units from the first part of this “How To” tutorial are 5 ⅝” square, my new fabric square will also need to be 5 ⅝” square.)

Place a half-square triangle on your work surface with the wrong side facing up. Then, place the QIP ruler on the square with the middle line running through opposite corners on the diagonal so that each corner has a different fabric. Using a sharp marking pen or pencil, draw a line on both sides of the ruler. These will be your sewing lines.

Place and align a marked half-square triangle unit on top of an un-pieced square with right sides together. Pin/clip if needed.

Using a straight stitch, sew on the edge of both marked lines closest to the middle. Trim your thread tails.

Using a cutting ruler and rotary cutter, not the QIP, cut down the middle between the two sewn lines to make your combination units.

Carefully press each unit toward the darker side if you can. Or press open.

Cut off the little tails from each unit and square up your new combination units.

You will end up with two combination units. Remember, I started with two 5 5/8” square pieces of fabric and my units are now each 5 1/4” square. (NOTE: You will end up with two versions of the combination block unit. The two smaller triangles in the completed combination units will mirror each other. If you look at the picture of them side-by-side, you will notice that in one unit the yellow square is on the bottom while in the other unit the blue square is on the bottom.)

• Allow yourself to play with the fabric colors and patterns you choose.
• Before you sew, test your straight stitch on a scrap piece of the fabric you are using and adjust your tension, etc. as needed.
• Know that if there is a little stretch to the fabric, your straight stitch may look a tiny bit wavy but it won’t be seen so don’t panic. Just try to keep your stitching close to the marked lines.
• If you have several different fabrics, it’s okay to use a neutral or gray thread.
• Do not be afraid to use your seam ripper if necessary.
• If you are worried that the lines you will be making on your squares will show on the top for any reason, use Heat Erasable Marking Pens. The lines will disappear when you press your units.

With the Quarter Inch Patchwork Ruler Set, you are able to quickly make sewing lines for making not only half-square triangles but combination units, hour glass units (see our blog: Using QIPS to make Hourglass Units) and more. It’s a time saving tool that allows you to play with your fabric and create your next project with ease.

We would love to see what you do with these quilt block combination units. Will it be mug rugs, placemats, a baby quilt or something else? Let your creativity soar! Share with us on the Madam Sew Quilting Facebook page.

Don’t want to stare at your computer screen or phone while making this project? Just print out the Making Combination Units PDF.

Cathy Jaynes
Quilt Blogging for MadamSew.com
cathy@madamsew.com

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